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Background: Diabetes insipidus is a syndrome characterized by polyuria, which is almost always associated with polydipsia. The most frequent cause is central diabetes insipidus, which is the result of an inadequate secretion of the antidiuretic hormone, and diagnosis involves differentiating it from other causes of polyuria and polydipsia., Case Presentation: Here, we present a clinical case of a previously healthy 13-year-old Nepali boy, who, in December 2022, was found to have intense polydipsia accompanied by polyuria. He had bilateral lower limb weakness at the time of presentation. Biochemical evaluation demonstrated raised serum sodium (181 mEq/L), serum creatinine (78 μmol/L), and serum uric acid (560 μmol/L) with suppressed serum potassium (2.7 mEq/L), which was the major concern to the clinicians. Further laboratory workup revealed an increased serum osmolarity (393.6 mOsm/kg) with reduced urine osmolarity (222.7 mOsm/kg). On contrast magnetic resonance imaging of the brain, a thick-walled third ventricular cyst with bilateral foramen obstruction, thin membrane-like structure at top of aqueduct of Sylvius with gross obstructive hydrocephalus (inactive), and compressed and thinned pituitary gland with no bright spot was observed. The laboratory findings, radiological findings, and case presentation provided the provisional diagnosis of diabetes insipidus due to hydrocephalus and third ventricular cyst., Conclusions: Central diabetes insipidus due to hydrocephalus, though rare, can have serious complications including the predilection to develop a deficit of other pituitary hormones. Thus, even if hydrocephalus is dormant with normal intracranial pressure, it must be addressed during investigations of central diabetes insipidus., (© 2024. The Author(s).)

Background: Hyponatremia associated with a low serum osmolality is a common and confounding electrolyte disorder. Correcting hyponatremia is also complicated, especially in the setting of chronic hyponatremia. Here, we provide a rational approach to accurately detecting and safely treating acute on chronic euvolemic hyponatremia in the setting of acute polydipsia with a chronic reset osmostat., Case Presentation: A 71-year-old hispanic gentleman with chronic hyponatremia presented with hiccups, polydipsia, and a serum sodium concentration of 120 mEq/L associated with diffuse weakness, inattentiveness, and suicidal ideation. Symptomatic euvolemic hyponatremia warranted hypertonic saline treatment in the acute phase and water restriction in the chronic phase. Both interventions resulted in improvement in symptoms and/or the serum sodium concentration, but to a serum sodium level that persistently remained below the normal range. Remarkably, the urine osmolality appropriately fell when the serum sodium concentration fell below 126 mEq/L. Also remarkable was the appropriate increase in urine osmolality when the serum sodium concentration exceeded 126 mEq/L. The preservation of both concentration and dilution, albeit at a lower-than-normal serum osmolality, shows that the osmostat regulating antidiuretic hormone release had been "reset." Both physiologic and pharmacologic resetting of the osmostat are discussed., Conclusions: Preservation of urinary concentrating and diluting ability at a lower-than-normal serum sodium concentration, especially in the setting of chronic hyponatremia, is diagnostic of a reset osmostat. The presence of a reset osmostat often confounds the treatment of concomitant acute hyponatremia. Early recognition of a reset osmostat avoids the need to normalize serum sodium concentration, expedites hospital discharge, and limits potential harm from overcorrecting acute hyponatremia., (© 2023. The Author(s).)

Background: Granulomatosis with polyangiitis, formerly known as Wegener granulomatosis, is a necrotizing vasculitis with granulomatous inflammation that belongs to the class of antineutrophil cytoplasmic antibodies-positive diseases. It occurs in a localized and a systemic form and may present with a variety of symptoms. Involvement of the upper respiratory tract is very common, while neurologic, endocrinological, and nephrological dysfunction may occur., Case Presentation: We describe the case of a 29-year-old Central European male patient presenting with severe bilateral sensorineural hearing loss, otorrhea, and one-sided facial nerve paralysis. The patient was unsuccessfully treated with i.v. antibiotics at another hospital in Berlin, and tympanic tubes were inserted. After presentation to our emergency room, he was hospitalized and further diagnostics started. Increased fluid intake and 12 kg weight gain over the last months were reported. The patient was diagnosed with granulomatosis with polyangiitis and diabetes insipidus. The patient's condition improved after treatment with rituximab., Discussion: A comprehensive PubMed search of all articles with granulomatosis with polyangiitis and diabetes insipidus was conducted to assess which combination of symptoms occurs simultaneously and whether other parts of the pituitary are commonly involved. The 39 selected articles, describing 61 patients, showed that ear-nose-throat involvement occurred most commonly, in 71% of cases. Of patients, 59% had involvement of the anterior pituitary gland, while true panhypopituitarism occurred in 13% of cases. Only one case report featured the same set of symptoms as described herein., Conclusion: Granulomatosis with polyangiitis is a highly variable disease, commonly involving the upper airways, but that may present with symptoms solely related to the pituitary gland. Clinicians should have a low threshold to investigate for granulomatosis with polyangiitis in patients with therapy-resistant otorrhea. Patients may present with a complex set of symptoms, and integrating different specialists when additional symptoms occur may lead to faster diagnosis., (© 2022. The Author(s).)

Introduction: Langerhans cell histiocytosis is a rare inflammatory bone marrow neoplasia that frequently affects bone, lung, skin and pituitary gland. Due to its broad spectrum of clinical presentation, an appropriate diagnosis might be difficult., History: A 54-year-old female patient complained of pain in her right ear for 5 months. On account of similar complaints, a mastoidectomy had already been performed 3 years ago. Histology at that time revealed nonspecific inflammation. Furthermore, she reported excessive thirst., Findings and Diagnosis: Computed tomography of the temporal bones showed osteolysis in the mastoid. Magnetic resonance imaging and bone scintigraphy assessed these changes as uncharacteristically inflammatory. Polydipsia proved to be a symptom of central diabetes insipidus in the water deprivation test. Finally, remastoidectomy provided histologic evidence of Langerhans cell histiocytosis., Therapy and Course: Besides systemic chemotherapy with cytarabine, the patient also received denosumab and desmopressin., Conclusion: Langerhans cell histiocytosis involving cranial bones is often associated with diabetes Insipidus. Knowledge about the distinctive constellation may lead to a more rapid diagnosis and improved prognosis., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

Background: Novel coronavirus disease 2019 (COVID-19) mainly affects the lungs, but can involve several other organs. The diagnosis of acute and chronic sequelae is one of the challenges of COVID-19. The current literature proposes that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may involve the hypothalamic-pituitary axis. In this case report, we present a unique case of new-onset central diabetes insipidus secondary to the COVID-19 disease in a 54-year-old woman., Case Presentation: A 54-year-old woman presented with the history of excessive thirst, polyuria, and polydipsia, six weeks after being infected by COVID-19. Laboratory tests revealed low urine osmolarity and increased serum osmolarity, and the patient was diagnosed with central diabetes insipidus. After administration of nasal desmopressin, urinary osmolarity increased, and the patient's symptoms improved. However, to stabilize her condition, desmopressin treatment was required., Conclusions: We reported a unique case of diabetes insipidus in a COVID-19 patient. Central diabetes insipidus may be included in clinical manifestations of the COVID-19, in case of new-onset polyuria and polydipsia following COVID-19 disease. Nevertheless, a causal relationship has not been established between the symptoms of the patient and the SARS-CoV-2 infection., (© 2022. The Author(s).)

Background: Diabetic ketoacidosis (DKA) is a potentially life-threatening complication of type 1 diabetes (T1D), and a leading cause of death in children aged <15 years with new-onset T1D., Aims: i) to assess the incidence of DKA in children and adolescents newly diagnosed with T1D over a 10-year period at a large regional center in China; and ii) to examine the clinical symptoms and demographic factors associated with DKA and its severity at diagnosis., Methods: We carried out a retrospective audit of a regional center, encompassing all youth aged <16 years diagnosed with T1D in 2009-2018 at the Children's Hospital, Zhejiang University School of Medicine (Hangzhou, China). DKA and its severity were classified according to ISPAD 2018 guidelines., Results: 681 children were diagnosed with T1D, 50.1% having DKA at presentation (36.0% mild, 30.0% moderate, and 33.9% severe DKA). The number of patients diagnosed with T1D progressively rose from approximately 39 cases/year in 2009-2010 to 95 cases/year in 2017-2018 (≈2.5-fold increase), rising primarily among children aged 5-9 years. DKA incidence was unchanged but variable (44.8% to 56.8%). At T1D diagnosis, 89% of patients reported polyuria and 91% polydipsia. Children presenting with DKA were more likely to report vomiting, abdominal pain, and particularly fatigue. DKA was most common among the youngest children, affecting 4 in 5 children aged <2 years (81.4%), in comparison to 53.3%, 42.7%, and 49.3% of patients aged 2-4, 5-9, and ≥10 years, respectively. Children with severe DKA were more likely to report vomiting, fatigue, and abdominal pain, but less likely to report polyuria, polydipsia, and polyphagia than those with mild/moderate DKA. Rates of severe DKA were highest in children aged <2 years (51.1%)., Conclusions: The number of children diagnosed with T1D at our regional center increased over the study period, but DKA rates were unchanged. With 9 of 10 children reporting polyuria and polydipsia prior to T1D diagnosis, increasing awareness of this condition in the community and among primary care physicians could lead to earlier diagnosis, and thus potentially reduce rates of DKA at presentation., Competing Interests: The 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 © 2021 Peng, Yuan, Chiavaroli, Dong, Huang, Wu, Ullah, Jin, Lin, Derraik and Fu.)

Purpose: Anorexia nervosa is a chronic disease which may result in various complications. In pediatric clinical practice, it is common to observe complications related to progressive cachexia caused by malnutrition; however, cases of severe complications, like electrolyte disorders, which represent a direct threat to life, due to polydipsia, are rarely observed. The purpose of this study is to highlight that excessive drinking is of primary importance in anorexia nervosa patients, as it can result in severe medical complications, including increased risk of death., Methods: We report the case of a 13-year-old girl with anorexia nervosa, who was referred to hospital with seizures, disorders of consciousness, and cardiorespiratory failure., Results: The unstable condition of the patient was attributed to hyponatremia (119 mmol/l), decreased serum osmolality (248 mmol/kg), and decreased urine osmolality (95 mmol/kg) caused by polydipsia (water intoxication) and persistent vomiting. The presented girl was drinking large amounts of water prior to a weigh-in to falsify her low body weight., Conclusions: Polydipsia is a common problem reported by patients with eating disorders, but one which rarely leads to serious clinical complications, due to severe hyponatremia. This case underscores the importance of careful evaluation of fluid intake and the need for regular monitoring of serum electrolytes in patients with anorexia nervosa. All clinicians treating patients with such disease, as well as the parents of sick children, should be familiar with this life-threatening condition., Level Iv: Evidence obtained from multiple time series with or without the intervention, such as case studies.

Background: The indirect water-deprivation test is the current reference standard for the diagnosis of diabetes insipidus. However, it is technically cumbersome to administer, and the results are often inaccurate. The current study compared the indirect water-deprivation test with direct detection of plasma copeptin, a precursor-derived surrogate of arginine vasopressin., Methods: From 2013 to 2017, we recruited 156 patients with hypotonic polyuria at 11 medical centers to undergo both water-deprivation and hypertonic saline infusion tests. In the latter test, plasma copeptin was measured when the plasma sodium level had increased to at least 150 mmol per liter after infusion of hypertonic saline. The primary outcome was the overall diagnostic accuracy of each test as compared with the final reference diagnosis, which was determined on the basis of medical history, test results, and treatment response, with copeptin levels masked., Results: A total of 144 patients underwent both tests. The final diagnosis was primary polydipsia in 82 patients (57%), central diabetes insipidus in 59 (41%), and nephrogenic diabetes insipidus in 3 (2%). Overall, among the 141 patients included in the analysis, the indirect water-deprivation test determined the correct diagnosis in 108 patients (diagnostic accuracy, 76.6%; 95% confidence interval [CI], 68.9 to 83.2), and the hypertonic saline infusion test (with a copeptin cutoff level of >4.9 pmol per liter) determined the correct diagnosis in 136 patients (96.5%; 95% CI, 92.1 to 98.6; P<0.001). The indirect water-deprivation test correctly distinguished primary polydipsia from partial central diabetes insipidus in 77 of 105 patients (73.3%; 95% CI, 63.9 to 81.2), and the hypertonic saline infusion test distinguished between the two conditions in 99 of 104 patients (95.2%; 95% CI, 89.4 to 98.1; adjusted P<0.001). One serious adverse event (desmopressin-induced hyponatremia that resulted in hospitalization) occurred during the water-deprivation test., Conclusions: The direct measurement of hypertonic saline-stimulated plasma copeptin had greater diagnostic accuracy than the water-deprivation test in patients with hypotonic polyuria. (Funded by the Swiss National Foundation and others; ClinicalTrials.gov number, NCT01940614 .).

Objective: Hyponatraemia due to excessive fluid intake (ie primary polydipsia [PP]) is common. It may culminate in profound hyponatraemia-carrying considerable risk of morbidity. However, data on patients with PP leading to hyponatraemia are lacking. Herein, we describe the characteristics of polydiptic patients hospitalized with profound hyponatraemia and assess 1-year outcomes., Design: Substudy of the prospective observational Co-MED Study., Patients: Patients with an episode of profound hyponatraemia (≤125 mmol/L) due to PP in the medical emergency were eligible and classified into psychogenic polydipsia (PsyP), dipsogenic polydipsia (DiP) and beer potomania (BP)., Measurements: Symptoms, laboratory findings and factors contributing to hyponatraemia (comorbidities, medication and liquid intake) were assessed. A 1-year follow-up was performed to evaluate recurrence of hyponatraemia, readmission rate and mortality., Results: Twenty-three patients were included (median age 56 years [IQR 50-65], 74% female), seven had PsyP, eight had DiP and eight had BP. Median serum sodium of all patients was 121 mmol/L (IQR 114-123), median urine osmolality 167 mmol/L (IQR 105-184) and median copeptin 3.6 mmol/L (IQR 1.9-5.5). Psychiatric diagnoses, particularly dependency disorder (43%) and depression (35%), were highly prevalent. Factors provoking hyponatraemia were found in all patients (eg acute water load, medication, stress). During the follow-up period, 67% of patients were readmitted, 52% of these with rehyponatraemia, and three patients (38%) with BP died., Conclusion: Patients with PP are more likely to be female and to have addictive and affective disorders. Given the high recurrence, rehospitalization and mortality rate, careful monitoring and long-term follow-up including controls of serum sodium, education and behavioural therapy are needed., (© 2017 John Wiley & Sons Ltd.)

Hyponatremia and its rapid correction is a well-known cause of osmotic demyelination most commonly affecting the pons. We report on a case of severe hyponatremia likely due to psychogenic polydipsia resulting in hypotonic hyperhydration with resulting cortical laminar necrosis on initial imaging, mimicking hypoxic brain damage. Pontine myelinolysis became apparent on follow-up imaging, illustrating the diagnostic challenges of extrapontine manifestations of severe hyponatremia., (© Georg Thieme Verlag KG Stuttgart · New York.)

Type 1 diabetes accounts for 5 to 10% of all diabetes cases. It appears most often during childhood or adolescence. We report the case of a hypertensive overweight patient of 79 years who consulted for asthenia in context of polyuria-polydipsia syndrome in which blood glucose assay revealed a diabetes mellitus associated with ketosis. Despite the age, the body mass index and the history of the patient, type 1 diabetes diagnosis should be considered in this clinical presentation with brutal and symptomatic early. The imagery excluding a pancreatic tumor and positive research of circulating autoantibodies will confirm the diagnosis.

Purpose: Polydipsia is one of the most serious and complicated problems causing morbidity and mortality in chronic mental health institutes. The pathophysiology of polydipsia in chronic schizophrenia remains unclear; as a result, no effective methods exist to deal with this serious problem. This report describes a patient with schizophrenia with polydipsia and seizures who benefitted from a behavioral modification program at a chronic mental health institute., Case Report: A 56-year-old schizophrenic man did not have a history of physical illnesses or seizures and developed seizures following polydipsia. Despite drug adjustment, his polydipsia was uncontrolled and he suffered from generalized tonic convulsions. After introducing a "water restriction program," his polydipsia and seizures were controlled., Conclusion: The "water restriction program" consisted of daily body weight monitoring and frequent checking of electrolyte data, both of which are inexpensive and simple. This program can be carried out by untrained nursing staff, who are the primary caregivers in chronic mental health institutes. Our case highlights an effective and inexpensive behavior modification program to deal with the difficult and complicated problems of polydipsia and seizures in chronic mental health institutes.

Context: The polyuria-polydipsia syndrome comprises primary polydipsia (PP) and central and nephrogenic diabetes insipidus (DI). Correctly discriminating these entities is mandatory, given that inadequate treatment causes serious complications. The diagnostic "gold standard" is the water deprivation test with assessment of arginine vasopressin (AVP) activity. However, test interpretation and AVP measurement are challenging., Objective: The objective was to evaluate the accuracy of copeptin, a stable peptide stoichiometrically cosecreted with AVP, in the differential diagnosis of polyuria-polydipsia syndrome., Design, Setting, and Patients: This was a prospective multicenter observational cohort study from four Swiss or German tertiary referral centers of adults >18 years old with the history of polyuria and polydipsia., Measurements: A standardized combined water deprivation/3% saline infusion test was performed and terminated when serum sodium exceeded 147 mmol/L. Circulating copeptin and AVP levels were measured regularly throughout the test. Final diagnosis was based on the water deprivation/saline infusion test results, clinical information, and the treatment response., Results: Fifty-five patients were enrolled (11 with complete central DI, 16 with partial central DI, 18 with PP, and 10 with nephrogenic DI). Without prior thirsting, a single baseline copeptin level >21.4 pmol/L differentiated nephrogenic DI from other etiologies with a 100% sensitivity and specificity, rendering a water deprivation testing unnecessary in such cases. A stimulated copeptin >4.9 pmol/L (at sodium levels >147 mmol/L) differentiated between patients with PP and patients with partial central DI with a 94.0% specificity and a 94.4% sensitivity. A stimulated AVP >1.8 pg/mL differentiated between the same categories with a 93.0% specificity and a 83.0% sensitivity., Limitation: This study was limited by incorporation bias from including AVP levels as a diagnostic criterion., Conclusion: Copeptin is a promising new tool in the differential diagnosis of the polyuria-polydipsia syndrome, and a valid surrogate marker for AVP. Primary Funding Sources: Swiss National Science Foundation, University of Basel.

Cordyceps militaris has long been used in prescriptions of traditional Chinese medicine as a tonic for the treatment of metabolic syndrome. Cordycepin with proven immunomodulatory, antitumor, and hepatoprotective properties is the main active metabolite of C militaris. Diabetes mellitus is a group of metabolic diseases in which the body is unable to regulate blood sugar levels. Hence, we hypothesized that cordycepin can normalize blood sugar levels and improve the indicators of diabetes. The aim of this study was to investigate the possible effects of cordycepin from C militaris on diabetes in an alloxan-induced diabetic mouse model. Diabetic mice were intraperitoneally administered different doses of cordycepin (8, 24, and 72 mg/kg body weight) daily for 21 days. Acute toxicity test on normal mice was carried out by giving them maximum tolerance dose of cordycepin (3600 mg/kg) daily. A 47% reduction of the blood glucose level, 214% increase of hepatic glycogen content, and significant improvement of oral glucose tolerance were noticed after the effective dose of cordycepin was administered. Polyphagia and polydipsia, the typical symptoms of diabetes, were partly alleviated. Moreover, cordycepin offered protective effects against diabetes-related kidney and spleen injury. Maximum tolerance dose test indicated that cordycepin at the large dose of 3600 mg/kg did not show significant effect on body weight and major organ in normal mice after intraperitoneal administration for 14 days. The results showed that cordycepin from C militaris that elicited hypoglycemic activity contributes to the regulation of glucose metabolism in liver in alloxan-induced diabetic mice. Therefore, a cordycepin treatment during diabetes can improve some of the metabolic syndrome symptoms by regulation of glucose absorption in vivo. Cordycepin may serve as a therapeutic agent in the treatment of diabetes and its related complications., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: To report a case of recurrent hyponatremia and rhabdomyolysis in a teenager with psychogenic polydipsia., Case Summary: A 16-year-old boy was admitted with recurrent episodes of hyponatremia and rhabdomyolysis secondary to psychogenic polydipsia. He was treated with hypertonic saline, intravenous fluids, and supportive care., Discussion: Psychogenic polydipsia is a condition characterized by compulsive drinking. Severe hyponatremia is a rare, but serious complication in patients with psychogenic polydipsia. Failure in cell volume regulatory mechanisms, defective osmoregulation, defective urinary dilution, and enhanced secretion of vasopressin are believed to play a role in the development of hyponatremia. Rhabdomyolysis can complicate severe hyponatremia, although the exact mechanism is not known. Antipsychotic drugs are also implicated in rhabdomyolysis., Conclusions: Severe hyponatremia and rhabdomyolysis can complicate psychogenic polydipsia. Patients receiving antipsychotic drugs with concomitant severe hyponatremia need to be monitored for rhabdomyolysis.

Hyponatremia is a serious, but often overlooked, electrolyte imbalance that has been independently associated with a wide range of deleterious changes involving many different body systems. Untreated acute hyponatremia can cause substantial morbidity and mortality as a result of osmotically induced cerebral edema, and excessively rapid correction of chronic hyponatremia can cause severe neurologic impairment and death as a result of osmotic demyelination. The diverse etiologies and comorbidities associated with hyponatremia pose substantial challenges in managing this disorder. In 2007, a panel of experts in hyponatremia convened to develop the Hyponatremia Treatment Guidelines 2007: Expert Panel Recommendations that defined strategies for clinicians caring for patients with hyponatremia. In the 6 years since the publication of that document, the field has seen several notable developments, including new evidence on morbidities and complications associated with hyponatremia, the importance of treating mild to moderate hyponatremia, and the efficacy and safety of vasopressin receptor antagonist therapy for hyponatremic patients. Therefore, additional guidance was deemed necessary and a panel of hyponatremia experts (which included all of the original panel members) was convened to update the previous recommendations for optimal current management of this disorder. The updated expert panel recommendations in this document represent recommended approaches for multiple etiologies of hyponatremia that are based on both consensus opinions of experts in hyponatremia and the most recent published data in this field., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Diabetic neuropathy is considered as a disease of the peripheral nervous system, but recent evidences suggest the involvement of central nervous system as well. In this study we evaluated the effect of Urtica dioica (UD) extract against memory dysfunction and hypoalgesia on a mouse model of streptozotocin (STZ) induced diabetic neuropathy. STZ (50 mg/kg, i.p. consecutively for 5 days) was used to induce diabetes, followed by treatment with the UD extract (50 mg/kg, oral) and rosiglitazone (5 mg/kg, oral) for 8 weeks. Cognitive functions were evaluated using Morris water maze and passive avoidance step through task. Pain thresholds were measured using thermal, mechanical and chemical induced hyperalgesia. We observed that chronic diabetes resulted in a decline in circulating insulin level, elevated blood glucose, reduced body weight, increased water intake, cognitive impairment and hypoalgesia. UD significantly reduced the blood glucose and polydypsia, as well as improved the body weight, insulin level, cognition and insensate neuropathy. In conclusion, UD showed results comparable to rosiglitazone in reversing the long standing diabetes induced complications such as central and peripheral neuronal dysfunction., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Background: It is important to ensure an adequate sodium and volume balance in neurosurgical patients in order to avoid the worsening of brain injury.Indeed, hyponatremia and polyuria, that are frequent in this patient population, are potentially harmful, especially if not promptly recognized.Differential diagnosis is often challenging, including disorders, which, in view of similar clinical pictures, present very different pathophysiological bases, such as syndrome of inappropriate antidiuresis, cerebral/renal salt wasting syndrome and diabetes insipidus., Case Presentation: Here we present the clinical report of a 67-year-old man with a recent episode of acute subarachnoid haemorrhage, admitted to our ward because of severe hyponatremia, hypokalemia and huge polyuria.We performed a complete workup to identify the underlying causes of these alterations and found a complex picture of salt wasting syndrome associated to primary polydipsia. The appropriate diagnosis allowed us to correct the patient hydro-electrolyte balance., Conclusion: The comprehension of the pathophysiological mechanisms is essential to adequately recognize and treat hydro-electrolyte disorders, also solving the most complex clinical problems.

Hyponatremia (serum sodium <135 mEq/L) is the most common electrolyte disorder. The severity of symptoms is related to how rapidly the condition develops and the degree of cerebral edema that results from the low serum level of sodium. Hypertonic saline and the new vasopressin receptor antagonists are highly effective treatments for severe symptomatic hyponatremia, yet they can result in severe neurological complications if sodium levels are restored too quickly. Hyponatremia is classified as hypovolemic, euvolemic, and hypervolemic. Treatments include administration of high-risk medications and fluid restriction to restore fluid and electrolyte balance and relieve cerebral effects. Nursing care to ensure safe outcomes involves multidisciplinary collaboration, close monitoring of serum sodium levels and intake and output, and assessment for neurological changes.

The present study demonstrates a key role for the oxysterol receptor liver X receptor β (LXRβ) in the etiology of diabetes insipidus (DI). Given free access to water, LXRβ(-/-) but not LXRα(-/-) mice exhibited polyuria (abnormal daily excretion of highly diluted urine) and polydipsia (increased water intake), both features of diabetes insipidus. LXRβ(-/-) mice responded to 24-h dehydration with a decreased urine volume and increased urine osmolality. To determine whether the DI was of central or nephrogenic origin, we examined the responsiveness of the kidney to arginine vasopressin (AVP). An i.p. injection of AVP to LXRβ(-/-) mice revealed a partial kidney response: There was no effect on urine volume, but there was a significant increase of urine osmolality, suggesting that DI may be caused by a defect in central production of AVP. In the brain of WT mice LXRβ was expressed in the nuclei of magnocellular neurons in the supraoptic and paraventricular nuclei of the hypothalamus. In LXRβ(-/-) mice the expression of AVP was markedly decreased in the magnocellular neurons as well as in urine collected over a 24-h period. The persistent high urine volume after AVP administration was traced to a reduction in aquaporin-1 expression in the kidney of LXRβ(-/-) mice. The LXR agonist (GW3965) in WT mice elicited an increase in urine osmolality, suggesting that LXRβ is a key receptor in controlling water balance with targets in both the brain and kidney, and it could be a therapeutic target in disorders of water balance.

In order to determine whether the renin-angiotensin system (RAS) has any physiologic function in bone metabolism, mice lacking the gene encoding the major angiotensin II receptor isoform, AT1a, were studied using micro CT scanning, histomorphometric, and biochemical techniques. Three-dimensional (3D) micro CT analysis of the tibial metaphysis revealed that both male and female AT1a knockout mice exhibited an increased trabecular bone volume along with increased trabecular number and connectivity. Histomorphometric analysis of the tibial metaphysis indicated that the parameters of bone formation as well as resorption were increased, which was also supported by elevated serum osteocalcin and carboxy-terminal collagen crosslink (CTX) concentrations in the AT1a-deficient mice. Osteoclastogenesis and osteoblastogenesis assays in ex vivo cultures, however, did not reveal any intrinsic alterations in the differentiation potential of AT1a-deficient cells. Quantitative RT-PCR using RNA isolated from the tibia and femur revealed that the receptor activator of NF-κB ligand (RANKL)/osteoprotegerin (OPG) ratio and the expression of stromal cell-derived factor (SDF)1α were increased, whereas that of SOST was decreased in AT1a-deficient bone, which may account for the increased bone resorption and formation, respectively. AT1a-deficient mice also displayed a lean phenotype with reduced serum leptin levels. They maintained high bone mass with advancing age, and were protected from bone loss induced by ovariectomy. Collectively, the data suggest that RAS has a physiologic function in bone remodeling, and that signaling through AT1a negatively regulates bone turnover and bone mass., (Copyright © 2011 American Society for Bone and Mineral Research.)

A 41-year-old white male with a history of alcoholism and depression was brought from prison into the emergency department (ED) after having had a witnessed tonic-clonic seizure lasting approximately 5 min. During the 24 h prior to admission, the patient's cell mate reported that he was restless and had consumed 11 litres of water. The patient had also been taking regular escitalopram for his depression. On arrival to the ED, the patient was found to have a sodium level of 112 mmol/l. After correction of his hyponatraemia the patient developed rhabdomyolisis with a creatine kinase level of 65 064 IU/l. To prevent an acute kidney injury a high volume alkaline diuresis protocol was started. Once corrected, his sodium level remained normal and he was discharged home after making a full neurological recovery. Rhabdomyolysis has rarely been associated with the correction of hyponatraemia.

We describe a complex case of hyponatraemia with two aetiologies. A 49-year-old man who drank 6 litres of dilute alcohol per day presented confused and oedematous with a serum sodium of 95 mmol/litre. Urine sodium was <10 mmol/litre and urine osmolality 440 mOsmol/kg. Chest x-ray demonstrated a globular heart. ECG showed saddle-shaped ST elevation. ECHO demonstrated a large pericardial effusion causing marked tamponade. Following pericardiocentesis there was a marked diuresis; serum sodium returned to normal after 2 weeks. A full recovery ensued. Cardiac tamponade is associated with antidiuresis via release of antidiuretic hormone (ADH). Tamponade is also associated with antinatriuresis. Antidiuresis and antinatriuresis usually balance in cardiac tamponade; excessive fluid intake may have caused an imbalance in this case.