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Hyponatremia is the most common electrolyte abnormality encountered in critically ill patients and is linked to heightened morbidity, mortality, and healthcare resource utilization. However, its causal role in these poor outcomes and the impact of treatment remain unclear. Plasma sodium is the main determinant of plasma tonicity; consequently, hyponatremia commonly indicates hypotonicity but can also occur in conjunction with isotonicity and hypertonicity. Plasma sodium is a function of total body exchangeable sodium and potassium and total body water. Hypotonic hyponatremia arises when total body water is proportionally greater than the sum of total body exchangeable cations, that is, electrolyte-free water excess; the latter is the result of increased intake or decreased (kidney) excretion. Hypotonic hyponatremia leads to water movement into brain cells resulting in cerebral edema. Brain cells adapt by eliminating solutes, a process that is largely completed by 48 h. Clinical manifestations of hyponatremia depend on its biochemical severity and duration. Symptoms of hyponatremia are more pronounced with acute hyponatremia where brain adaptation is incomplete while they are less prominent in chronic hyponatremia. The authors recommend a physiological approach to determine if hyponatremia is hypotonic, if it is mediated by arginine vasopressin, and if arginine vasopressin secretion is physiologically appropriate. The treatment of hyponatremia depends on the presence and severity of symptoms. Brain herniation is a concern when severe symptoms are present, and current guidelines recommend immediate treatment with hypertonic saline. In the absence of significant symptoms, the concern is neurologic sequelae resulting from rapid correction of hyponatremia which is usually the result of a large water diuresis. Some studies have found desmopressin useful to effectively curtail the water diuresis responsible for rapid correction., Competing Interests: Declaration of Conflicting InterestsThe author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Hyponatraemia has indeed been extensively studied from multiple angles, including volume status, tonicity, and aetiology; however, the specific consideration of the osmolar gap (OG) within the context of hyponatraemia and its potential impact on their overall outcomes received limited attention in research. The current study represents an effort to address this gap in our understanding. This prospective exploratory study was conducted on adults aged 14 years and older at the Indus Hospital, Karachi, from 2017 to 2020. The study involved categorising severity of hyponatraemia and volume status. The osmolar gap (OG) was calculated and categorised as either increased (OG>10) or normal (OG<10). Among the 262 patients included in the study, there were 139 females and 123 males. Elevated OG was observed in 141(53.8%) patients. There were 28 (10.7%) recorded fatalities and majority of these individuals had an elevated OG. These findings underscore the importance for clinicians to consider the osmolar gap when managing patients with hyponatraemia.

Purpose of Review: To provide a contemporary overview of the pathophysiology, evaluation, and treatment of hyponatremia in heart failure (HF)., Recent Findings: Potassium and magnesium losses due to poor nutritional intake and treatment with diuretics cause an intracellular sodium shift in HF that may contribute to hyponatremia. Impaired renal blood flow leading to a lower glomerular filtration rate and increased proximal tubular reabsorption lead to an impaired tubular flux through diluting distal segments of the nephron, compromising electrolyte-free water excretion. Hyponatremia in HF is typically a condition of impaired water excretion by the kidneys on a background of potassium and magnesium depletion. While those cations can and should be easily repleted, further treatment should mainly focus on improving the underlying HF and hemodynamics, while addressing congestion. For decongestive treatment, proximally acting diuretics such as sodium-glucose co-transporter-2 inhibitors, acetazolamide, and loop diuretics are the preferred options., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The bone-derived hormone fibroblast growth factor-23 (FGF23) has recently received much attention due to its association with chronic kidney disease and cardiovascular disease progression. Extracellular sodium concentration ([Na + ]) plays a significant role in bone metabolism. Hyponatremia (lower serum [Na + ]) has recently been shown to be independently associated with FGF23 levels in patients with chronic systolic heart failure. However, nothing is known about the direct impact of [Na + ] on FGF23 production. Here, we show that an elevated [Na + ] (+20 mM) suppressed FGF23 formation, whereas low [Na + ] (-20 mM) increased FGF23 synthesis in the osteoblast-like cell lines UMR-106 and MC3T3-E1. Similar bidirectional changes in FGF23 abundance were observed when osmolality was altered by mannitol but not by urea, suggesting a role of tonicity in FGF23 formation. Moreover, these changes in FGF23 were inversely proportional to the expression of NFAT5 (nuclear factor of activated T cells-5), a transcription factor responsible for tonicity-mediated cellular adaptations. Furthermore, arginine vasopressin, which is often responsible for hyponatremia, did not affect FGF23 production. Next, we performed a comprehensive and unbiased RNA-seq analysis of UMR-106 cells exposed to low versus high [Na + ], which revealed several novel genes involved in cellular adaptation to altered tonicity. Additional analysis of cells with Crisp-Cas9-mediated NFAT5 deletion indicated that NFAT5 controls numerous genes associated with FGF23 synthesis, thereby confirming its role in [Na + ]-mediated FGF23 regulation. In line with these in vitro observations, we found that hyponatremia patients have higher FGF23 levels. Our results suggest that [Na + ] is a critical regulator of FGF23 synthesis., Competing Interests: Conflict of interest The authors declare no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Observational hemodialysis (HD) studies report an association between hyponatremia and increased mortality. As volume overload is also associated with mortality, we wished to determine whether hyponatremia is linked to increased extracellular water (ECW). We measured ECW, total body water (TBW) and body composition predialysis with multifrequency bioimpedance, arm strength with pinch gauge and hand grip strength (PS, HGS), standard biochemistry profiles, comorbidity and clinical frailty scores (CFS). We reviewed 324 patients, 195 (60.2%) male, mean age 62.3 ± 15.6 years. Thirty-eight (11.7%) patients were hyponatremic (sodium ≤135 mmol/L), ECW/height 2 was not different, but ECW/TBW (0.409 ± 0.016 vs. 0.402 ± 0.016, p < 0.01), C reactive protein (CRP) (9(4-6) vs. 5(2-12) g/L, p < 0.05), CFS (5(4-6) vs. 4(3-6), p < 0.05) were higher in hyponatremic patients, whereas appendicular lean mass index (8.6 ± 1.7 vs. 9.4 ± 1.8 kg/m2, p < 0.01), serum albumin (36.3 ± 5.5 vs. 38.8 ± 5.0 g/L, p < 0.01) and PS (3.7(2.7-4.7) vs. 4.7 (3.2-6.5) kg, p < 0.05)) were lower. Both serum sodium, and serum sodium after adjustment for glucose were associated with serum creatinine (β 4.26, (95% confidence limits [CL] 1.9-6.7), β 3.98 (CL 1.6-6.4), both p = 0.001, respectively) and negatively with CRP (β -0.76, [CL] -1.5 to -0.5), β -0.72 (CL -1.44 to -0.12), p = 0.036, p = 0.046, respectively) in a multivariable model. Hyponatremic HD patients did not simply have an increased ECW, as the increased ECW/TBW and ECW/ICW ratios were more likely secondary to loss of muscle mass and strength, associated with increased CRP and reduced albumin, suggesting that hyponatremia is associated with inflammation, loss of muscle mass and increasing frailty., (© 2021 International Society for Apheresis, Japanese Society for Apheresis, and Japanese Society for Dialysis Therapy.)

Background: Hyponatremia is one of the most common electrolyte disorders observed in hospitalized and ambulatory patients. Hyponatremia is associated with increased falls, fractures, prolonged hospitalisation and mortality. The clinical importance of hyponatremia in the renal transplant field is not well established, so the aim of this study was to determine the relationships between hyponatremia and mortality as main outcome and renal function decline and graft loss as secondary outcome among a prospective cohort of renal transplant recipients., Methods: This prospective cohort study included 1315 patients between 1 May 2008 and 31 December 2014. Hyponatremia was defined as sodium concentration below 136 mmol/L at 6 months after transplantation. The main endpoint was mortality. A secondary composite endpoint was also defined as: rapid decline in renal function (≥5 mL/min/1.73 m 2 drop of the eGFR/year), graft loss or mortality., Results: Mean sodium was 140 ± 3.08 mmol/L. 97 patients displayed hyponatremia with a mean of 132.9 ± 3.05 mmol/L. Hyponatremia at 6 months after transplantation was associated neither with mortality (HR: 1.02; p = 0.97, 95% CI: 0.47-2.19), nor with the composite outcome defined as rapid decline in renal function, graft loss or mortality (logrank test p = 0.9)., Conclusions: Hyponatremia 6 months after transplantation is not associated with mortality in kidney allograft patients.

Objectives: Although new-born screening (NBS) for classical congenital adrenal hyperplasia (C-CAH) has been available for decades, it is not widely implemented. We assessed the usefulness of introducing NBS for C-CAH, by analyzing presenting status of infants with C-CAH, over the past two decades, in Sri Lanka., Methods: This retrospective clinic-based study, from the largest tertiary children's hospital in Sri Lanka, analyzed initial presenting features of children with C-CAH from 1999 to 2018, in the absence of NBS for CAH, and included gender-based comparisons., Results: Features suggestive of impending adrenal-crisis were seen at initial presentation in >80 % (dehydration 70%, hyponatremia 65%, hyperkalemia 47%, vomiting 45%, hypoglycemia 22%, collapse 20%). Hyperpigmentation was seen in 78%, and consanguinity in 27%. There were fewer affected males (n = 12) compared to females (n = 28). Most girls (96%) had virilized genitalia, and 16 faced uncertainty about gender at birth. Median age at diagnosis was 20 days. More than 70% of children had SW-CAH (males = 9 and females = 20). There were fewer males with SW-CAH, and all had features of impending adrenal crisis, including severe hyponatremia in 50%, while 62% of girls also developed hyponatremia and 33% had hyperkalemia, prior to treatment. Treatment of SW-CAH was initiated at a median age of 30 days in boys, and 10 days of age in girls., Conclusion: Many boys and girls with C-CAH from Sri Lanka presented late with impending adrenal crisis. Males were diagnosed later, and some possibly succumbed to C-CAH undiagnosed. These findings support including CAH in NBS programs to avert preventable childhood morbidity and mortality., (© 2021 Walter de Gruyter GmbH, Berlin/Boston.)

SARS-CoV-2 is the cause of COVID-19. Since the outbreak and rapid spread of COVID-19, it has been apparent that the disease is having multi-organ system involvement. Still its effect in the endocrine system is not fully clear and data on cortisol dynamics in patients with COVID-19 are not yet available. SARS-CoV-2 can knock down the host's cortisol stress response. Here we present a case of a 51-year-old man vomiting for 10 days after having confirmed COVID-19 infection. He had hypotension and significant hyponatraemia. Work-up was done including adrenocorticotropic hormone stimulation test. He was diagnosed as suffering from adrenal insufficiency and started on steroids with subsequent improvement in both blood pressure and sodium level. COVID-19 can cause adrenal insufficiency. Clinicians must be vigilant about the possibility of an underlying relative cortisol deficiency in patients with COVID-19., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Apelin and arginine-vasopressin (AVP) are conversely regulated by osmotic stimuli. We therefore hypothesized that activating the apelin receptor (apelin-R) with LIT01-196, a metabolically stable apelin-17 analog, may be beneficial for treating the Syndrome of Inappropriate Antidiuresis, in which AVP hypersecretion leads to hyponatremia. We show that LIT01-196, which behaves as a potent full agonist for the apelin-R, has an in vivo half-life of 156 minutes in the bloodstream after subcutaneous administration in control rats. In collecting ducts, LIT01-196 decreases dDAVP-induced cAMP production and apical cell surface expression of phosphorylated aquaporin 2 via AVP type 2 receptors, leading to an increase in aqueous diuresis. In a rat experimental model of AVP-induced hyponatremia, LIT01-196 subcutaneously administered blocks the antidiuretic effect of AVP and the AVP-induced increase in urinary osmolality and induces a progressive improvement of hyponatremia. Our data suggest that apelin-R activation constitutes an original approach for hyponatremia treatment.

A 41-year-old woman was diagnosed with pre-eclampsia at 35 weeks gestation. She was treated with antihypertensives but, unfortunately, her condition became complicated by severe hyponatraemia. Her sodium levels rapidly dropped to 125 mmol/L. The cause for the hyponatraemia was the syndrome of inappropriate antidiuretic hormone secretion. She was initially managed with fluid restriction, but an emergency caesarean section was necessary in view of fetal distress. Her sodium levels returned to normal within 48 hours of delivery.Pre-eclampsia is rarely associated with hyponatraemia. A low maternal sodium level further increases the mother's risk for seizures during this state. Additionally, the fetal sodium rapidly equilibrates to the mother's and may result in fetal tachycardia, jaundice and polyhdraminios. All these factors may necessitate an emergency fetal delivery., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Volume and electrolyte evaluation and management is seen frequently in primary care practices. Some of the most common abnormalities encountered in outpatient practices are prerenal azotemia, dysnatremias, and altered potassium levels. Perturbations in volume or electrolyte concentrations can lead to serious organ dysfunction as well as hemodynamic collapse. This review focuses on the maintenance and regulation of intravascular volume and electrolytes, specifically sodium and potassium., Competing Interests: Disclosure The authors have nothing to disclose., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Dysnatremia is associated with increased mortality in patients with community-acquired pneumonia. SARS-COV2 (Severe-acute-respiratory syndrome caused by Coronavirus-type 2) pneumonia can be fatal. The aim of this study was to ascertain whether admittance dysnatremia is associated with mortality, sepsis, or intensive therapy (IT) in patients hospitalized with SARS-COV2 pneumonia. This is a retrospective study of the HOPE-COVID-19 registry, with data collected from January 1 th through April 31 th , 2020. We selected all hospitalized adult patients with RT-PCR-confirmed SARS-COV2 pneumonia and a registered admission serum sodium level (SNa). Patients were classified as hyponatremic (SNa <135 mmol/L), eunatremic (SNa 135-145 mmol/L), or hypernatremic (SNa >145 mmol/L). Multivariable analyses were performed to elucidate independent relationships of admission hyponatremia and hypernatremia, with mortality, sepsis, or IT during hospitalization. Four thousand six hundred sixty-four patients were analyzed, median age 66 (52-77), 58% males. Death occurred in 988 (21.2%) patients, sepsis was diagnosed in 551 (12%) and IT in 838 (18.4%). Hyponatremia was present in 957/4,664 (20.5%) patients, and hypernatremia in 174/4,664 (3.7%). Both hyponatremia and hypernatremia were associated with mortality and sepsis. Only hyponatremia was associated with IT. In conclusion, hyponatremia and hypernatremia at admission are factors independently associated with mortality and sepsis in patients hospitalized with SARS-COV2 pneumonia., Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT04334291, NCT04334291., Competing Interests: IR and MC have given talks sponsored by Otsuka, and worked in an advisor capacity for Otsuka. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Ruiz-Sánchez, Núñez-Gil, Cuesta, Rubio, Maroun-Eid, Arroyo-Espliguero, Romero, Becerra-Muñoz, Uribarri, Feltes, Trabattoni, Molina, García Aguado, Pepe, Cerrato, Alfonso, Castro Mejía, Roubin, Buzón, Bondia, Marin, López Pais, Abumayyaleh, D’Ascenzo, Rondano, Huang, Fernandez-Perez, Macaya, de Miguel Novoa, Calle-Pascual, Estrada Perez, Runkle and HOPE COVID-19 investigators.)

Intravenous fluids are frequently used in hospitalized children. Hypotonic fluids have been the standard of care in pediatrics for many years. This might be explained by the empiricism of early recommendations favoring fluids with dextrose, but an insufficient amount of sodium. The risk of hyponatremia (<135mmol/L) might be increased by the occurrence of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in the course of common acute diseases (e.g., bronchiolitis, acute gastroenteritis, encephalitis, meningitis) in children. Severe hyponatremia (<130mmol/L) is often associated with neurologic complications leading to sequelae or even death. Over the last few years, hyponatremia induced by hypotonic fluids has been increasingly reported, and significant progress has been made in the understanding of cerebral edema and osmotic demyelination. Several randomized clinical trials have shown weak but significant evidence that isotonic fluids were superior to hypotonic solutions in preventing hyponatremia. However, clinical practices have not changed much in France, as suggested by the analysis of intravenous fluids ordered from the Assistance Publique-Hôpitaux de Paris (AP-HP) central pharmacy (PCH) in 2017. Therefore, it would be advisable that national guidelines be released under the French Health Authorities regarding the safe infusion of infants and children., (Copyright © 2020 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.)

Hyponatremia is frequently seen in patients with ascites secondary to advanced cirrhosis and portal hypertension. Although not apparent in the early stages of cirrhosis, the progression of cirrhosis and portal hypertension leads to splanchnic vasodilation, and this leads to the activation of compensatory mechanisms such as renin-angiotensin-aldosterone system (RAAS), sympathetic nervous system, and antidiuretic hormone (ADH) to ameliorate low circulatory volume. The net effect is the avid retention of sodium and water to compensate for the low effective circulatory volume, resulting in the development of ascites. These compensatory mechanisms lead to impairment of the kidneys to eliminate solute-free water in decompensated cirrhosis. Nonosmotic secretion of antidiuretic hormone (ADH), also known as arginine vasopressin, further worsens excess water retention and thereby hyponatremia. The management of hyponatremia in this setting is a challenge as conventional therapies for hyponatremia including fluid restriction and correction of hypokalemia are frequently inefficacious. In this review, we discuss the pathophysiology, complications, and various treatment modalities, including albumin infusion, selective vasopressin receptor antagonists, or hypertonic saline for patients with severe hyponatremia and those awaiting liver transplantation.

Objective: In this study, we examined the effect of acute hyponatremia associated with vasopressin (AVP) on the responses of the isolated rat's MCAs and PAs to acidosis, nitric oxide donor (SNAP) and to endothelium-dependent vasodilator ATP., Methods: The studies were performed on isolated, perfused and pressurized MCAs and PAs in control conditions and during AVP-associated hyponatremia. Hyponatremia was induced in vitro by lowering Na + concentration from 144 to 121 mmol/L in intra- and extravascular fluid in the presence of AVP., Results: Parenchymal arterioles showed greater response to an increase in H + and K + ions concentration and to ATP in comparison with MCAs in control normonatremic conditions. Both PAs and MCAs constricted in response to acute hyponatremia associated with AVP. Interestingly, disordered regulation of vascular tone was observed in PAs but not in MCAs. The abnormalities in the regulation comprised a significant reduction of PA response to acidosis and the absence of the response to the administration of SNAP or ATP., Conclusions: Arginine vasopressin-associated hyponatremia leads to constriction and dysregulation of PAs which may impair neurovascular coupling., (© 2020 John Wiley & Sons Ltd.)

Hyponatremia is a common condition affecting hospitalized and ambulatory patients as well. The clinical spectrum of hyponatremia can range from asymptomatic laboratory findings to severely symptomatic conditions such as acute epileptic seizures. Etiologies of hyponatremia include excessive intake of solute-free fluids, side-effects of medication, diseases associated with hypervolemic states such as congestive heart failure, and the syndrome of inappropriate antidiuretic hormone secretion (SIADH).As hyponatremia can be a potentially life-threatening condition, it requires an efficient management with the goal of identifying the etiology and to subsequently provide adequate treatment, while avoiding treatment-related adverse effects such as overcorrection and pontine myelinolysis. This article summarizes the pathophysiology and differential diagnosis, as well as useful diagnostic tests and therapy of hyponatremia in a practice-oriented manner., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

Competing Interests: Competing interests: None declared.

Rationale: Hyponatremia occurs frequently in the hospital setting and may be attributable to a host of etiologies. Drugs are frequently implicated. Trimethoprim-sulfamethoxazole (TMP/SMX) represents a well-recognized pharmacologic precipitant of drug-induced hyponatremia, with several reports extant in the retrievable literature. Nephrologists thus debate the mechanisms giving rise to TMP/SMX-induced hyponatremia and the precise mechanism by which treatment with TMP/SMX generates reductions of serum sodium concentration remain controversial. The agent has a well-known effect of antagonizing the effects of aldosterone upon the distal nephron. Renal salt wasting and the syndrome of inappropriate antidiuretic hormone secretion represent implicated mechanistic intermediaries in TMP/SMX-induced hyponatremia., Patient Concerns: The patient endorsed no explicit concerns., Diagnoses: We describe the case of an 83-year-old female clinically diagnosed with pneumonia found to have an initial serum sodium in the range of 130 to 134 mEq/L consistent with mild hyponatremia upon admission. Sputum cultures grew Achromobacter xylosoxidans susceptible to TMP/SMX. The patient's serum sodium concentration precipitously decline following institution of treatment with TMP/SMX to 112 to 114 mEq/L during the course of 5 days., Interventions: Severe hyponatremia proved recalcitrant to initial therapy with supplemental salt tabs and standard doses of the vasopressin receptor antagonist tolvaptan., Outcomes: Escalating doses of tolvaptan increased the patient's sodium to 120 to 124 mEq/L. The patient was transferred to another hospital for further management. During her stay, the patient did not exhibit frank or obvious clinical features consistent with hyponatremia nor readily appreciable evidence of volume depletion., Lessons: TMP/SMX represents a frequent, though underreported cause of hyponatremia in the hospital setting several authors believe natriuresis may represent the most common mechanism underlying TMP/SMX-induced hyponatremia. Evidence implicating natriuresis to be mechanistic in TMP/SMX-induced hyponatremia include clinically appreciable hypovolemia and resolution of hyponatremia with oral or intravenous salt repletion. Salt repletion failed to monotherapeutically enhance our patient's hyponatremiadisfavoring renal salt wasting as originately mechanistic. Contemporaneous refractoriness of serum sodium to fluid restriction nor standard doses of tolvaptan confounded our initial attempts to mechanistically attribute the patient's hyponatremia to a specific cause. Clinical euvolemia and rapid response of hyponatremia to exceptionally high doses of tolvaptan strongly favors syndrome of inappropriate antidiuretic hormone to represent the chief mechanism by which TMP/SMX exacerbates hyponatremia.

Background: The impact of chronic moderate and profound hyponatremia on neurocognitive performance, motor skills, and mood stability has not been investigated systematically so far, and results regarding mild to moderate hyponatremia are inconsistent. Furthermore, it is not known whether treatment has an effect on outcome in these patients., Methods: A total of 130 hospitalized patients with confirmed euvolemic hyponatremia (<130 mEq/L) were subjected to a test battery (Mini-Mental State Examination, DemTect, Trail-Making Tests A and B, Beck Depression Inventory, Timed-up-and-go Test) before and after treatment; additionally, 50 normonatremic group-matched patients served as reference group., Results: The scores of all tested domains were significantly worse in the hyponatremia group (median serum sodium [Na + ] 122 (119-126) mEq/L) as compared to the reference group (P <0.001), and the odds of obtaining a pathological test result increased markedly with more profound hyponatremic states (odds ratios between 5.0 and 21.8 in the group with Na + <120 mEq/L compared to reference group). Inversely, treatment led to a significant amelioration of all test results with medium to large effect sizes. Linear regression models revealed the increment of Na + as an important predictor of test outcome., Conclusion: We demonstrate a clear association between lower levels of Na + beyond mild hyponatremia and impairment of neurocognitive and motor performance as well as mood disorders. Our analysis further suggests a causal role of hyponatremia in this context. However, there are apparent differences between the distinct tested domains warranting further investigations., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Retrospective single institution observational study.The aim of the present study was to analyze the influence of early extensive posterior decompression on complications in patients with severe traumatic cervical spinal cord injury (tcSCI).Cervical SCI is associated with a high prevalence of hyponatremia and cardiopulmonary dysfunction. However, very few studies have focused on this exploration to reduce the incidence of SCI early complications.We reviewed the medical records of consecutive patients undergoing extensive posterior decompression within 24 h for severe tcSCI (American Spinal Injury Association Impairment Scale [AIS] A to C) admitted between January 2009 and January 2018. The data collected retrospectively included age, gender, mechanism, and level of SCI, AIS grade, fracture or dislocation, electrolyte, and cardiopulmonary complications.Of the 97 enrolled patients, the baseline AIS grade was AIS A in 14, AIS B in 31, and AIS C in 52. Improvement of at least two AIS grades was found in 26 (26.8%), and improvement of at least one grade was found in 80.4% of patients at discharge. Twenty-nine (29.9%) patients had mild hyponatremia, 8 (8.2%) had moderate hyponatremia, and 3 (3.1%) had severe hyponatremia during hospitalization. The incidences of hyponatremia, hypotension, and tracheotomy were 41.2%, 13.4%, and 6.2%, respectively. The mean forced vital capacity (FVC) on admission and at discharge was 1.34 ± 0.46 L and 2.21 ± 0.41 L (P < .0001), respectively. Five patients developed pneumonia.Our results suggest that early expansive posterior decompression significantly reduces the incidence of hyponatremia, hypotension, and tracheotomy by promoting recovery of spinal cord function after severe tcSCI.

Clinical symptoms of active tuberculosis (TB) can range from a simple cough to more severe reactions, such as irreversible lung damage and, eventually, death, depending on disease progression. In addition to its clinical presentation, TB has been associated with several other disease-induced systemic complications, such as hyponatremia and glucose intolerance. Here, we provide an overview of the known, although ill-described, underlying biochemical mechanisms responsible for the clinical and systemic presentations associated with this disease and discuss novel hypotheses recently generated by various omics technologies. This summative update can assist clinicians to improve the tentative diagnosis of TB based on a patient's clinical presentation and aid in the development of improved treatment protocols specifically aimed at restoring the disease-induced imbalance for overall homeostasis while simultaneously eradicating the pathogen. Furthermore, future applications of this knowledge could be applied to personalized diagnostic and therapeutic options, bettering the treatment outcome and quality of life of TB patients., (Copyright © 2020 American Society for Microbiology.)

A 57-year-old woman presented with severe lethargy, dizziness and nausea 1 week after transsphenoidal resection of a growth hormone secreting pituitary adenoma. She was found to have severe hyponatremia of 115 mmol/L. Importantly, she was neurologically intact and clinically euvolaemic. Her fluid intake was restricted and her sodium levels increased to 131 mmol/L over 4 days. She made a full recovery.She was diagnosed with isolated second-phase diabetes insipidus, a state of symptomatic hypoosmolar hyponatremia that usually occurs 7-10 days after transsphenoidal surgery. The sodium levels improve with fluid restriction., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Background Arginine vasopressin dependent antidiuresis plays a key role in water-sodium retention in heart failure. In recent years, the role of glucocorticoids in the control of body fluid homeostasis has been extensively investigated. Glucocorticoid deficiency can activate V2R (vasopressin receptor 2), increase aquaporins expression, and result in hyponatremia, all of which can be reversed by glucocorticoid supplement. Methods and Results Heart failure was induced by coronary artery ligation for 8 weeks. A total of 32 rats were randomly assigned to 4 groups (n=8/group): sham surgery group, congestive heart failure group, dexamethasone group, and dexamethasone in combination with glucocorticoid receptor antagonist RU486 group. An acute water loading test was administered 6 hours after drug administration. Left ventricular function was measured by a pressure-volume catheter. Protein expressions were determined by immunohistochemistry and immunoblotting. The pressure-volume loop analysis showed that dexamethasone improves cardiac function in rats with heart failure. Western blotting confirmed that dexamethasone remarkably reduces the expressions of V2R, aquaporin 2, and aquaporin 3 in the renal-collecting ducts. As a result of V2R downregulation, the expressions of glucocorticoid regulated kinase 1, apical epithelial sodium channels, and the furosemide-sensitive Na-K-2Cl cotransporter were also downregulated. These favorable effects induced by dexamethasone were mostly abolished by the glucocorticoid receptor inhibitor RU486, indicating that the aforementioned effects are glucocorticoid receptor mediated. Conclusions Glucocorticoids can reverse diluted hyponatremia via inhibiting the vasopressin receptor pathway in rats with heart failure.

Background: To explore the underlying mechanisms leading to the occurrence of hyponatremia and enhanced urinary sodium excretion in brain trauma patients using sodium balance and urinary biochemical analysis., Methods: We conducted a retrospective analysis of a local database prospectively collected in 60 brain trauma patients without chronic renal dysfunction. Metabolic and hemodynamic parameters were averaged over three consecutive periods over the first seven days after admission. The main outcome investigated in this study was the occurrence of at least one episode of hyponatremia., Results: Over the study period, there was a prompt decrease in sodium balance (163 ± 193 vs. -12 ± 154 mmol/day, p < 0.0001) and free water clearance (- 0.7 ± 0.7 vs. -1.8 ± 2.3 ml/min, p < 0.0001). The area under the ROC curves for sodium balance in predicting the occurrence of hyponatremia during the next period was 0.81 [95% CI: 0.64-0.97]. Variables associated with averaged urinary sodium excretion were sodium intake (R 2  = 0.26, p < 0.0001) and fractional excretion of urate (R 2  = 0.15, p = 0.009). Urinary sodium excretion was also higher in patients with sustained augmented renal clearance over the study period (318 ± 106 vs. 255 ± 135 mmol/day, p = 0.034)., Conclusion: The decreased vascular volume resulting from a negative sodium balance is a major precipitating factor of hyponatremia in brain trauma patients. Predisposing factors for enhanced urinary sodium excretion were high sodium intake, high fractional excretion of urate and augmented renal clearance over the first seven days after ICU admission.

Hyponatraemia, a water-electrolyte disorder diagnosed in patients with subarachnoid haemorrhage (SAH), increases a risk of persistent vasospasm. In majority of cases, hyponatraemia results from inappropriate secretion of vasopressin (AVP). The effect of AVP-associated hyponatraemia on cerebral vasculature is unknown. The present study aimed to elucidate the role of AVP in the response of the middle cerebral artery (MCA) of the rat to hyponatraemia. Isolated, cannulated, and pressurized rat MCAs were perfused/superfused with physiological (Na +  = 144 mmol/L) buffer or low-sodium (Na +  = 121 mmol/L) buffer containing either AVP or angiotensin II (ANG II). ANG II was used to check if the effect of low plasma sodium concentration combined with AVP on the MCA tone is unique to vasopressin. At physiological Na + concentration, vasopressin (1.4 × 10 -11  mol/L) or angiotensin II (10 -9  mol/L) resulted in relaxation of the MCA. Substitution of low-sodium for the normal sodium buffer with the same concentration of AVP, resulted in the constriction of the MCA. This effect was absent after removal of the endothelium, administration of vasopressin V 1 receptor antagonist or concomitant inhibition of endothelin-1 receptors and synthesis of thromboxane A 2. In contrast, no constriction of the MCA in low-sodium buffer was observed when AVP was replaced with ANG II. Our data suggest that presence of vasopressin and low sodium ion concentration results in the change of endothelium phenotype from pro-vasodilatory to pro-vasoconstrictory. This phenomenon may be an overlooked factor contributing to vasospasm in SAH patients with hyponatraemia caused by inappropriate antidiuretic hormone secretion (SIADH)., (© 2019 John Wiley & Sons Australia, Ltd.)

The relationship between hyponatremia, depression symptoms, and cognitive impairments in patients receiving hemodialysis treatment remain unclear. This study aimed to examine the impact of past-year average serum sodium levels on current depression symptoms and cognitive impairments in patients receiving hemodialysis, with adjustment for possible confounders. A total of 200 participants were recruited for this study. Depression symptoms and cognitive impairments were assessed using the Patient Health Questionnaire and Perceived Deficits Questionnaire-5, respectively. Additionally, sociodemographic features, physical health, metabolic factors, and substance use information were collected. Significant associations between serum sodium levels, depression symptoms, and cognitive impairments were found after multivariate regression analysis. Furthermore, such differences were observed profoundly in moderate to profound hyponatremia. Our study revealed exclusive relationships between hyponatremia, depression symptoms, and cognitive impairments. As such, programs of cognitive rehabilitation and emotional regulation should be included in the prevention of chronic kidney disease for moderate to profound hyponatremia., (© 2019 International Society for Apheresis, Japanese Society for Apheresis, and Japanese Society for Dialysis Therapy.)

Neurotuberculosis usually responds well to standard antitubercular therapy. Some; patients have prolonged course A 11 year old boy diagnosed TBM, an immunocompetent patient, had an unusual course of illness in the form of prolonged fever, persistent hyponatremia and CSF; pleocytosis despite adequate treatment. Clinical course in the management of TBM can be; protracted with complications despite adequate therapy., (Copyright © 2019 Tuberculosis Association of India. Published by Elsevier B.V. All rights reserved.)

Background: Delayed hyponatremia is a serious complication seen after pituitary surgery. We document the incidence, presentation, outcome and risk factors for this condition., Materials and Methods: This was a retrospective study involving 222 patients operated for nonfunctioning pituitary macroadenomas between 2007-2016. Delayed hyponatremia was defined as serum sodium <135 mmol/L, occurring after the third post-operative day. Hyponatremia was categorized as mild (134-130 mmol/L), moderate (129-125 mmol/L) and severe (<125 mmol/L). All patients received intravenous (0.9%) saline, intravenous hydrocortisone and 12g oral salt over 24 hours. Patients with severe hyponatremia were given 3% saline., Results: Fifty eight patients (26%) developed delayed hyponatremia; thirty (13.5%) had severe hyponatremia. Delayed hyponatremia usually (43.1%) occurred on the seventh post-operative day (range, 3-15 days). Most patients (81%) remained asymptomatic; 11 patients developed vomiting (5), seizures (3), lethargy (1), fever (1) and paralytic ileus (1). One patient developed status epilepticus. Patients who manifest symptoms had lower sodium levels as compared to those who did not have symptoms (mean 117.7 mmol/L vs. 123 mmol/L; P < 0.01). Male gender (P = 0.002) and intra-operative CSF leak (P = 0.003) were risk factors for developing delayed hyponatremia. Other factors like, age, pre-operative cortisol levels, extent of resection and post-operative diabetes insipidus did not correlate with the occurrence of delayed hyponatremia. Patients who maintained their mean serum sodium levels >138 mmol/L (day 1-day 3) were unlikely to develop delayed hyponatremia (sensitivity, 55.2% and specificity, 83.9%), positive predictive value, 63.2% [confidence interval (CI) 48, 76.7%] and negative predictive value, 78.8% (CI 70.6, 85.5%). In most patients (57%) hyponatremia was corrected within 48 hours (h)., Conclusions: We recommend routine serum sodium testing on the seventh post-operative day for all patients undergoing pituitary surgery. Most patients remain asymptomatic and unless they are detected early they can go on to develop serious complications., Competing Interests: None

Background: Diuretic requirements in patients with acute decompensated heart failure (ADHF) and hyponatraemia versus normonatraemia on admission has not been previously explored., Methods: The Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) trial dataset was utilised to examine the characteristics and diuretic requirements of patients with ADHF with hyponatraemia or normonatraemia on admission., Results: Patients with ADHF and admission hyponatraemia (n = 103, average Na 130.2 meq/L) had a higher degree of congestion evident in higher frequency of jugular venous distension (JVD) >12 cmH 2 O (p = 0.007), 2+ lower extremity oedema (p = 0.001), and higher right atrial pressure (p = 0.007), compared with normonatraemic patients (n = 327, average Na 138.6 meq/L). Despite a similar baseline furosemide dose in both groups (median 200 mg), the hyponatraemia group received higher in-hospital furosemide (280 vs. 200 mg, in both groups, respectively, p < 0.001) which represented a higher percentage of furosemide utilisation relative to baseline, compared with the normonatraemia group (33% vs 0%, in both groups respectively, p = 0.007). With in-hospital diuresis, the Na level of hyponatraemic subjects started significantly increasing at discharge and up to 6 months after randomisation-all relative to baseline. Hyponatraemic patients had significantly lower systolic blood pressure (SBP) longitudinally at multiple time points compared with normonataremic patients, but it did not further decrease despite the higher furosemide dose in the former group., Conclusion: Patients with ADHF and hyponatraemia on admission had a higher degree of congestion and required higher doses of furosemide, compared with normonatraemic subjects. The lower Na and SBP in this instance should not lead to withholding or minimising diuretic dosage which should rather be dictated by volume status., (Copyright © 2019 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.)

The most used experimental mouse model of hyponatremia and elevated intracranial pressure (ICP) is intraperitoneal injection of water in combination with antidiuretics. This model of water intoxication (WI) results in extreme pathological changes and death within 1 h. To improve preclinical studies of the pathophysiology of elevated ICP, we characterized diuresis, cardiovascular parameters, blood ionogram and effects of antidiuretics in this model. We subsequently developed a new mouse model with mild hyponatremia and sustained increased ICP. To investigate the classical protocol (severe WI), C57BL/6mice were anesthetized and received an intraperitoneal injection of 20% body weight of MilliQ water with or without 0.4 µg·kg -1 desmopressin acetate (dDAVP). Corresponding Sham groups were also studied. In the new WI protocol (mild WI), 10% body weight of a solution containing 6.5 mM NaHCO 3 , 1.125 mM KCl and 29.75 mM NaCl was intraperitoneally injected. By severe WI, ICP and mean arterial pressure increased until brain stem herniation occurred (23 ± 3 min after injection). The cardiovascular effects were accelerated by dDAVP. Severe WI induced a halt to urine production irrespective of the use of dDAVP. Following the new mild WI protocol, ICP also increased but was sustained at a pathologically high level without inducing herniation. Mean arterial pressure and urine production were not affected during mild WI. In conclusion, the new mild WI protocol is a superior experimental model to study the pathophysiological effects of elevated ICP induced by water intoxication.

Background: In a previous study we found a significant correlation between dystocia and hyponatraemia that developed during labour. The present study examined a possible causal relationship. In vitro studies often use area under the curve (AUC) determined by frequency and force of contractions as a measure of myometrial contractility. However, a phase portrait plot of isometric contraction, obtained by plotting the first derivate of contraction against force of contraction, could indicate that bi-or multiphasic contractions might be less effective compared to the smooth contractions., Material and Methods: Myometrial biopsies were obtained from 17 women undergoing elective caesarean section at term. Each biopsy was divided into 8 strips and mounted isometrically in a force transducer. Seven biopsies were used in the first part of the study when half of the strips were immersed in the hyponatraemic study solution S containing Na+ 120 mmol/L and observed for 1 hour, followed by 1 hour in normonatraemic control solution C containing Na+ 136 mmol/L, then again in S for 1 hour, and finally 1 hour in C. The other half of the strips were studied in reverse order, C-S-C-S. The remaining ten biopsies were included in the second part of the study. Response to increasing doses of oxytocin (OT) in solutions S and C was studied. In the first part of the study we calculated AUC, and created phase portrait plots of two different contractions from the same strip, one smooth and one biphasic. In both parts of the study we registered frequency and force of contractions, and described appearance of the contractions., Results: First part of the study: Mean (median) contractions per hour in C: 8.7 (7.6), in S 14,3 (13). Mean (SD) difference between groups 5.6 (4.2), p = 0.018. Force of contractions in C: 11.8 (10.2) mN, in S: 10.8 (9.2) mN, p = 0.09, AUC increased in S; p = 0.018. Bi-/multiphasic contractions increased from 8% in C to 18% in S, p = 0.001. All changes were reversible in C. Second part of the study: Frequency after OT 1.65 x 10-9 M in C:3.4 (2.9), in S: 3.8 (3.2), difference between groups: p = 0.48. After OT 1.65 x 10-7 M in C: 7.8 (8.9), increase from previous OT administration: p = 0.09, in S: 8.7 (9.0), p = 0.04, difference between groups, p = 0.32. Only at the highest dose of OT dose was there an increase in force of contraction in S, p = 0.05, difference between groups, p = 0.33. Initial response to OT was more frequently bi/multiphasic in S, reaching significance at the highest dose of OT(1.65 x 10-7 M), p = 0.015. when almost all contractions were bi/multiphasic., Conclusion: Hyponatraemia reversibly increased frequency of contractions and appearance of bi-or multiphasic contractions, that could reduce myometrial contractility. This could explain the correlation of hyponatraemia and instrumental delivery previously observed. Contractions in the hyponatraemic solution more frequently showed initial multiphasic contractions when OT was added in increasing doses. Longer lasting labours carry the risk both of hyponatraemia and OT administration, and their negative interaction could be significant. Further studies should address this possibility., Competing Interests: The authors have declared that no competing interests exist.

Objective: Hyponatremia is a common electrolyte disorder in patients with stroke, which leads to various fatal complications. We performed a systematic review and meta-analysis to investigate the outcomes of acute stroke patients with hyponatremia., Methods: We searched MEDLINE, EMBASE, and the Cochrane Library databases for relevant literature in English published up to March 2020. Two review authors independently screened and selected the studies by assessing the eligibility and validity based on the inclusion criteria. Mortality at 90 days was set as the primary end point, and in-hospital mortality and length of hospital stay were set as the secondary end points. We conducted the data synthesis and analyzed the outcomes by calculating the odds ratio (OR) and mean difference., Results: Of 835 studies, 15 studies met the inclusion criteria (n = 10,745). The prevalence rate of stroke patients with hyponatremia was 7.0-59.2%. They had significantly higher 90-day mortality (OR, 1.73; 95% confidence interval (CI), 1.24-2.42) and longer length of hospital stay (mean difference, 10.68 days; 95% CI, 7.14-14.22) than patients without hyponatremia. Patients with hyponatremia had a higher tendency of in-hospital mortality than those without hyponatremia (OR, 1.61; 95% CI, 0.97-2.69)., Conclusions: The development of hyponatremia in the clinical course of stroke is associated with higher short-term mortality and a longer hospital stay. Although the causal relationship is unclear, hyponatremia could be a significant predictor of poor outcomes after stroke., (© 2020 S. Karger AG, Basel.)

Nurses need to have a firm grasp of normal and pathophysiological mechanisms of sodium and water balance to fully understand assessment findings and establish a rationale for a patient's plan of care. While multiple mechanisms control sodium and water balance, antidiuretic hormone and aldosterone are the most important hormonal influences. This article, the first in a new series designed to improve nurses' understanding of the physiological abnormalities underlying many disorders, reviews the common etiologies and symptoms of hyponatremia and hypernatremia, as well as the role of nursing care in patients with imbalances of sodium and water. Case studies guide the reader through relevant medical history and examination findings to an understanding of both the nursing and medical plans of care.

Hyponatremia is the most common electrolyte abnormality encountered both in the inpatient and outpatient clinical settings in the United States. Rapid correction leads to a deranged cerebral osmotic gradient causing osmotic demyelination syndrome. Coexisting azotemia is considered to be protective against osmotic demyelination syndrome owing to its counteractive effect on osmolarity change that occurs with rapid hyponatremia correction. In this article, we report the case of a 37-year-old male who presented with altered mentation, acute azotemia, and severe electrolyte derangements, with serum blood urea nitrogen 160 mg/dL, creatinine 8.4 mg/dL, sodium 107 mEq/L, potassium 6.1 mEq/L, bicarbonate 7 mEq/L, and anion gap of 33. Given refractory hyperkalemia with electrocardiogram changes, emergent dialysis was performed. Despite our efforts to avoid rapid correction, serum sodium was corrected to 124 mEq/L and blood urea nitrogen decreased to 87 mg/dL at the end of the 5-hour dialysis session. Fortunately, hospital course and 4-week post-discharge clinic follow-ups were uncomplicated with no neurological sequela confirmed by neurological examination and magnetic resonance imaging.

Addison disease is due to the destruction or dysfunction of the entire adrenal cortex. Nowadays, the causes of adrenal insufficiency are autoimmune disease for 70-90% and tuberculosis for 7-20%. Many typical signs and symptoms, such as hyponatremia, hyperkalaemia, or renal insufficiency can represent the reasons for a nephrology consultation, especially in conditions of urgency, and they can easily be confused with other causes. Moreover, the fact that in a short time range we have diagnosed the three cases described as a guide in this review, has aroused our attention as nephrologists on a disease in which we have probably already encountered but without recognizing it. The blood tests showed in all three patients severe electrolyte disorders and acute renal failure which will be discussed in their physiopathogenetic mechanisms. In a peculiar way, these alterations were not controlled with repolarizing solutions, fluid replacement and increased volemia, but only after steroid administration. In conclusion, in this review all the known pathogenic mechanisms causing disorders of nephrological interest in adrenal insufficiency are discussed.

We describe a 67-year-old man admitted from a mental health unit with an incidental finding of hyponatraemia on routine blood tests. Laboratory investigations were in keeping with syndrome of inappropriate antidiuretic hormone secretion (SIADH). He had been recently commenced on mirtazapine. During his inpatient stay, he became increasingly confused. Review of a previous admission with hyponatraemia raised the possibility of voltage-gated potassium channel antibody-associated limbic encephalitis, although subsequent investigations deemed this unlikely as a cause of hyponatraemia. Although his sodium levels improved with fluid restriction, serial point-of-care testing proved misleading in monitoring the efficacy of treatment as inconsistencies were seen in comparison with laboratory testing. The cause of hyponatraemia may have been medication-induced SIADH and/or polydipsia. This case highlights the importance of collating detailed histories and laboratory blood testing to guide management in cases of hyponatraemia of unknown aetiology., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: Investigation of association of ONSD with hyponatremia in symptomatic patients., Methods: 89 patients who were diagnosed to have hyponatremia (Na + <135 mmol/L) were prospectively analyzed and compared with 72 patients who have normal serum sodium levels presented to ED at the same time interval. Subjects' demographic properties including age and sex were recorded, as were admission symptoms, serum Na + level, and pre-treatment and post-treatment optic nerve sheath diameter (ONSD)., Results: The mean age of the study population was 62.3 ± 17.6 years, and the control group 55.1 ± 20.0 years (p < 0.05). There was a significant difference between the patient group's pre-treatment and post-treatment OSNDs compared to the controls (p < 0.05). There was a significant negative correlation between the admission sodium level and ONSD in the patient group (p < 0.05). In the pre-treatment period, patients with symptoms had a significantly greater mean ONSD than those without symptoms (0.546 ± 0.068 mm vs 0.448 ± 0.081 mm; p < 0.05). The area under the curve was 0.870; the cut-off level calculated for hyponatremia was 0.49 mm, which had a sensitivity of 81% and a specificity of 81.9%., Conclusion: Ultrasonic imaging of ONSD measurement in the emergency department appears to reflect changes consistent with ICP changes in hyponatremia and change in serum sodium., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: Hyponatremia has been frequently observed after aneurysmal subarachnoid hemorrhage (SAH), and some data have suggested a correlation with symptomatic cerebral vasospasm and poor outcomes. The present prospective study investigated sodium and water disturbances after aneurysmal SAH with regard to symptomatic vasospasm and patient outcomes., Methods: Data from all patients with aneurysmal SAH treated in our department during a 2-year period were collected. Daily natriuresis, sodium levels, water balance, and serum and urine osmolality were measured at 4 different points: day 1 of admission or bleeding, day 3, day 7, and day 14-21 or discharge. The clinical parameters (i.e., Hunt and Hess grade, aneurysm location and treatment, onset of vasospasm) were reviewed. The patients' outcome was assessed using the Glasgow outcome score and modified Rankin scale., Results: A total of 101 patients (70 women; median age, 52 years) were enrolled in the present study. Of these 101 patients, 59.4% had a good grade SAH (Hunt and Hess grade 1-3). The most common aneurysm location was the anterior communicating artery (37%). The results from an electrolyte analysis were available for ≤91 patients at days 1 and 78 at discharge. In 33 patients (32.7%), hyponatremia had been diagnosed at any time point. Hyponatremia was most frequently observed at day 1 and later at days 7-10. A location in the anterior communicating artery resulted in hyponatremia more frequently only at day 1 (P = 0.007). The main causes of hyponatremia were cerebral salt-wasting syndrome (early onset) and syndrome of inappropriate antidiuretic hormone secretion (early and late onset)., Conclusion: Distinguishing early- and late-onset hyponatremia is of major relevance, because different therapeutic approaches are required. Only hyponatremia at discharge resulted in less favorable outcomes., (Copyright © 2019 Elsevier Inc. All rights reserved.)

This observational study investigated the impact of hyponatremia resolution on the results of a comprehensive geriatric assessment (CGA) in 150 patients with age ≥70 years and serum sodium <130 mEq/L. The test battery including Barthel index of Activities of Daily Living (ADL) and various tests of neurocognitive function, motor performance and mood stability was applied on admission and at discharge. Changes of individual test results (Δ) were analyzed and normonatremic patients matched for age, gender, and ADL served as reference group. Most CGA test results improved. The improvement was more pronounced in the hyponatremia group with respect to ADL (ΔADL: 14.3 ± 17.1 vs. 9.8 ± 14.7; p = 0.002) and MMSE (ΔMMSE: 1.8 ± 3.0 vs. 0.7 ± 1.9; p = 0.002). Effect sizes were small (i.e., >0.2) in the overall analysis for ΔADL and ΔMMSE and moderate (i.e., >0.5) for ΔMMSE in the euvolemic subgroup. Beneficial effects on ΔADL and ΔMMSE were only observed in the subgroup of patients in which [Na + ] was raised by >5 mEq/L and multivariable linear regression analysis confirmed [Na + ] increase to be an independent predictor of MMSE improvement. Resolution of hyponatremia has a beneficial impact on the geriatric patients' overall functional status, in particular in euvolemic cases.

Exercise-associated hyponatremia (EAH) is defined as a plasma sodium concentration of <135 mmol/L during or after endurance and ultra-endurance performance and was first described by Timothy Noakes when observed in ultra-marathoners competing in the Comrades Marathon in South Africa in the mid-1980s. It is well-established that a decrease in plasma sodium concentration <135 mmol/L occurs with excessive fluid intake. Clinically, a mild hyponatremia will lead to no or very unspecific symptoms. A pronounced hyponatremia (<120 mmol/L) will lead to central nervous symptoms due to cerebral edema, and respiratory failure can lead to death when plasma sodium concentration reaches values of <110-115 mmol/L. The objective of this narrative review is to present new findings about the aspects of sex, race location, sports discipline, and length of performance. The prevalence of EAH depends on the duration of an endurance performance (i.e., low in marathon running, high to very high in ultra-marathon running), the sports discipline (i.e., rather rare in cycling, more frequent in running and triathlon, and very frequent in swimming), sex (i.e., increased in women with several reported deaths), the ambient temperature (i.e., very high in hot temperatures) and the country where competition takes place (i.e., very common in the USA, very little in Europe, practically never in Africa, Asia, and Oceania). A possible explanation for the increased prevalence of EAH in women could be the so-called Varon-Ayus syndrome with severe hyponatremia, lung and cerebral edema, which was first observed in marathon runners. Regarding the race location, races in Europe seemed to be held under rather moderate conditions whereas races held in the USA were often performed under thermally stressing conditions (i.e., greater heat or greater cold)., Competing Interests: The authors declare no conflict of interest.

A 61-year-old Caucasian woman with a history of hypertension presented with a week's history of confusion falls and back pain was found to have hyponatraemia from secretion of antidiuretic hormone and treated appropriately. Given her persistent symptoms, despite a normal CT head on presentation, an MRI head was obtained, showing vasogenic oedema in line with posterior reversible encephalopathy syndrome (PRES). Despite aggressive antihypertensives and supportive measures, unfortunately, her condition deteriorated, with increased confusion, new left-sided flaccid paresis, paraesthesias and worsening of the back pain. Following further testing including a cerebrospinal fluid analysis, finally diagnosed with an atypical presentation of Guillain-Barre syndrome (GBS), and prompt management with intravenous immunoglobulins was initiated. She recovered clinically and returned to near-normal function on follow-up. We use this case to suggest the importance of dysautonomia in GBS and various clinical manifestations it can present with, including PRES and hyponatraemia., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Hyponatremia is a well-established poor prognostic marker in patients with heart failure. Whether the mortality risk is comparable among different races of patients with heart failure and hyponatremia is unknown., Materials and Methods: Consecutive patients admitted with acute decompensated heart failure and an admission sodium level<135 mEq/L from 1/1/2001 through 12/31/10 were identified. Patients were divided into four groups based on self-reported race: white, African American, Hispanic and other. African Americans were used as the reference group for statistical analysis. The primary outcome was all-cause mortality., Results: We included 4,343 patients, from which 1,356 (31%) identified as white, 1,248 (29%) as African American, 780 (18%) as Hispanic and 959 (22%) as other. During a median follow-up of 23 months, a total of 2,384 patients died: 678 were African American, 820 were white, 298 were Hispanic and 588 were other. After adjusting for baseline demographics, comorbidities and medication use, Hispanic patients had a 45% less risk of death as compared to African Americans (HR .55, CI .48-.64, p<0.05). There was no difference in mortality between white and African American patients (HR 1.04, CI .92-1.2, p = 0.79)., Conclusion: Hispanic patients admitted for heart failure and who were hyponatremic on admission had an independent lower risk of mortality compared to other groups. These findings may be due to the disparate activity of the renin-angiotensin-aldosterone system among various racial groups. This observational study is hypothesis generating and suggests that treatment of patients with heart failure and hyponatremia should perhaps be focused more on renin-angiotensin-aldosterone system reduction in certain racial groups, yet less in others., Competing Interests: The authors have declared that no competing interests exist.

Spinal cord injury (SCI) is associated with a range of secondary health issues. Altered neurological function can complicate diagnosis, which may have serious consequences. Here we present the case of a tetraplegic person presenting with confusion and bradycardia. Initial testing revealed severe hyponatraemia (sodium 96 mmol/L) and ST elevation associated with labile blood pressure. Delayed further investigation identified sigmoid volvulus-endoscopic decompression led to resolution of haemodynamic lability and a diagnosis of autonomic dysreflexia. Low mood and poor documentation in the community were found to contribute to poor compliance with an established bowel management plan. Inpatient care involved electrolyte correction and establishment of regular bowel motions. The patient was discharged at baseline neurology with psychological support. This case highlights poor awareness of the secondary health issues affecting those with SCI and the complex relationship between mental and physical health., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Dysnatremias are common electrolyte disturbances with significant morbidity and mortality. In chronic dysnatremias a slow correction rate (<10 mmol/L/24 h) is indicated to avoid neurological complications. In acute dysnatremias (occurring <48 h) a rapid correction rate may be indicated. Most guidelines do not differ between acute and chronic dysnatremias. In this review, we focus on the evidence-based treatment of acute dysnatremias., Methods: A literary search in PubMed and Embase. A total of 72 articles containing 79 cases were included, of which 12 cases were excluded due to lack of information., Results: Of 67 patients (70% women) with acute dysnatremia, 60 had hypo- and 7 had hypernatremia. All patients with hyper- and 88% with hyponatremia had a rapid correction rate (> 10 mmol/L/24 h). The median time of correction was 1 day in patients with hypo- and 2.5 days in patients with hypernatremia. The mortality was 7% in patients with hypo- and 29% in patients with hypernatremia., Interpretation: Severe acute dysnatremias have significant mortality and require immediate treatment. A rapid correction rate may be lifesaving and is not associated with neurological complications. Chronic dysnatremias, on the other hand, are often compensated and thus less severe. In these cases a rapid correction rate may lead to severe cerebral complications.

Competing Interests: Competing interestsThe BMJ has judged that there are no disqualifying financial ties to commercial companies. The authors declare the following other interests: none. Further details of The BMJ policy on financial interests is here: https://www.bmj.com/about-bmj/resources-authors/forms-policies-and-checklists/declaration-competing-interests