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Objectives: We present an adolescent in whom olfactory neuroblastoma (ONB) was detected on follow-up magnetic resonance imaging (MRI) 2.5 years after SIADH diagnosis. Our case contrasts prior pediatric reports in which ONB and SIADH were diagnosed concurrently., Case Presentation: A previously healthy 13-year-old girl was found to have SIADH during evaluation for restrictive eating. Work-up ruled out adrenal, thyroid and paraneoplastic causes, diuretic use, and vasopressin receptor and aquaporin channel mutations. Brain MRI was normal except for paranasal sinus (PNS) inflammatory changes to the left fronto-maxillary sinuses and frontoethmoidal recess. The sodium levels normalized with fluid restriction (800-900 ml/m 2 /day). Multiple repeated attempts to liberalize fluid intake resulted in recurrent hyponatremia. Follow-up brain MRIs 4 and 11 months after the initial presentation showed persistent PNS inflammatory changes. A subsequent brain MRI 31 months after initial presentation demonstrated a lesion in the left frontoethmoidal recess extending into the left nasal cavity and biopsy showed low grade ONB. The patient underwent surgery with normalization of serum sodium on liberalized fluid intake. Seven days after surgery, she had recurrence of SIADH, and brain MRI showed remnant of the ONB at the fovea ethmoidalis. She completed adjuvant radiotherapy though her SIADH persisted., Conclusions: Our case highlights the importance of considering ONB in the evaluation of children with SIADH. Idiopathic SIADH is rare in children and if no cause is identified, computed tomography of sinuses and nasal endoscopy should be considered earlier in the work-up of these patients, particularly in the absence of sinus symptoms., 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 © 2024 Sasidharan Pillai, Boxerman, Groblewski, DeNardo, Faizan, Topor, Robilliard and Serrano-Gonzalez.)

This report describes a suspected case of paraneoplastic syndrome of inappropriate antidiuretic hormone (SIADH) in a 5-year-old male entire Australian Kelpie associated with a gastric adenocarcinoma. The dog had a history of chronic vomiting and presented with hyponatraemia, hypokalaemia, hypochloraemia and increased urinary sodium. Computed tomography identified the presence of a gastric tumour and histopathology confirmed a pyloric gastric adenocarcinoma. Removal of the tumour via a Billroth I procedure resulted in rapid resolution of electrolyte derangements. The dog was still alive six months postoperatively with no recurrence of either SIADH or tumour at the time of publication., (© 2024 Australian Veterinary Association.)

BACKGROUND West Nile virus (WNV) is a vector-borne flavivirus that is typically transmitted by Aedes and Anopheles mosquitos. WNV infection typically presents with symptoms consistent with viral meningitis, which include fever, headache, and meningeal signs. WNV infections are typically self-resolving, with symptoms lasting 3-10 days. Although uncommon, patients with WNV infection can be afflicted with hyponatremia, although the etiology is unclear. Because of encephalitis, neuroinflammation may be involved in the deterioration of adrenal signaling, leading to salt wasting. CASE REPORT We present the case of a 75-year-old man who presented with headache, neck pain, photophobia, and viral illness symptoms. He was found to be profoundly hyponatremic, concerning for SIADH. He had a sodium drop to 117 mmol/L, leading to further lethargy and confusion. He received 3% saline, fluid restriction, and salt tablets, and more common causes of SIADH were ruled out. MRI revealed the absence of the posterior pituitary bright spot. He was subsequently found to have positive WNV titers and improved with continued supportive treatment. CONCLUSIONS WNV presents a unique challenge to providers due to its difficult diagnosis and association with hyponatremia. There is no clear role for specific medical treatment such as corticosteroids vs IV immunoglobulins. Supportive care is recommended for those testing positive for WNV. Clinicians should consider the possibility of viral infections, such as WNV, in patients living in endemic areas who present with unexplained hyponatremia, cognitive symptoms, and relevant history.

A 78-year-old man was admitted to the hospital with a 4-day history of fever and confusion. Physical examination revealed oral dryness and decreased skin turgor. Blood tests showed hyponatremia (121.5 ‍mEq/l), and cerebrospinal fluid examination revealed positivity for herpes simplex virus 1 (HSV-1) via polymerase chain reaction. He was diagnosed with herpes simplex encephalitis and initiated acyclovir treatment. The hyponatremia was diagnosed as cerebral salt wasting syndrome (CSWS) and treated with hypertonic saline infusion and fludrocortisone. The cerebrospinal fluid HSV-1 DNA became negative, and the serum sodium levels normalized. Hyponatremia complicated with encephalitis is often caused by the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), whereas CSWS is rare, mostly observed in tuberculous meningitis. Differentiating between the SIADH and CSWS is important as they require distinct therapeutic strategies.

Introduction: A reninoma (juxtaglomerular cell tumor) is a rare cause of secondary hypertension that can present with headaches alongside the triad of severe hypertension, hypokalemia, and metabolic alkalosis., Case Presentation: We describe a case of a 15-year-old previously healthy girl who presented with headaches and hypertensive urgency who had severe hypokalemia, moderate hyponatremia, and elevated aldosterone and renin levels. Abdominal ultrasound and MRI with contrast revealed a unilateral mass localized to the right kidney. Despite treatment of her hypertension, she had persistent hyponatremia with clinical euvolemia which was consistent with the paraneoplastic syndrome of inappropriate antidiuretic hormone secretion (SIADH). She underwent radical nephrectomy which normalized her blood pressure and aldosterone and renin values. The pathology findings were consistent with a reninoma with a mitotic rate of 1-2 mitoses per 10 high power fields., Discussion: Hypertension in the pediatric age group requires workup to rule out secondary causes. The classic triad of hypertension, hypokalemia, and metabolic alkalosis warrants assessment for aldosterone-mediated hypertension which can be a result of a renin-producing tumor. Curative approach requires surgical resection of the tumor. Reninomas may rarely manifest with a paraneoplastic phenomenon including SIADH, as seen in our case. Although reninomas are benign tumors, there are also a few reports of malignant transformation and metastases. Features uncommon in reninomas such as mitotic activity warrant long-term surveillance., (© 2023 S. Karger AG, Basel.)

BACKGROUND Hashimoto's encephalopathy (HE) is an autoimmune encephalopathy that can involve various symptoms including psychosis. Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) may be a complication in some neurological diseases. However, the simultaneous occurrence of subacute psychosis and SIADH as the manifestation of HE, observed in the present case, has rarely been reported. CASE REPORT A 72-year-old man was hospitalized with a 4-month history of abnormal behaviors, including talkativeness, stopping consumption of coffee and cigarettes, hoarding garbage, and sleep disorders. On physical examination, increased and incoherent speech with flight of idea and delusion were observed. The Mini-Mental State Examination score was 28/30. Laboratory findings included hyponatremia due to SIADH and a positive result for anti-thyroid and anti-NH2 terminal of alpha-enolase antibodies. Cerebrospinal fluid examination revealed only elevation of IL-6. Brain magnetic resonance imaging was unremarkable; however, (I-123)-iodoamphetamine single-photon emission computed tomography showed extensive hyperperfusion involving the brainstem and bilateral frontal and medial temporal lobes. Electroencephalography showed generalized slow waves, but there were no epileptiform discharges. After 2 courses of high-dose intravenous methylprednisolone followed by oral prednisolone, his symptoms improved. Based on the findings of clinical features and steroid responsiveness, he was diagnosed with HE. Oral prednisolone and antipsychotic drugs were decreased without a relapse and he was discharged to his home. CONCLUSIONS Although psychosis complicating SIADH is rare, HE should be considered in the differential diagnosis because of its treatment efficacy.

Background and Objectives: There is considerable controversy as to which of the 2 operating modalities (microsurgical or endoscopic transnasal surgery) currently used to resect pituitary adenomas (PAs) is the safest and most effective intervention. We compared rates of clinical outcomes of patients with PAs who underwent resection by either microsurgical or endoscopic transnasal surgery., Methods: To independently assess the outcomes of each modality type, we sought to isolate endoscopic and microscopic PA surgeries with a 1:1 tight-caliper (0.01) propensity score-matched analysis using a multicenter, neurosurgery-specific database. Surgeries were performed between 2017 and 2020, with data collected retrospectively from 12 international institutions on 4 continents. Matching was based on age, previous neurological deficit, American Society of Anesthesiologists (ASA) score, tumor functionality, tumor size, and Knosp score. Univariate and multivariate analyses were performed., Results: Among a pool of 2826 patients, propensity score matching resulted in 600 patients from 9 surgery centers being analyzed. Multivariate analysis showed that microscopic surgery had a 1.91 odds ratio (OR) ( P = .03) of gross total resection (GTR) and shorter operative duration ( P < .01). However, microscopic surgery also had a 7.82 OR ( P < .01) for intensive care unit stay, 2.08 OR ( P < .01) for intraoperative cerebrospinal fluid (CSF) leak, 2.47 OR ( P = .02) for postoperative syndrome of inappropriate antidiuretic hormone secretion (SIADH), and was an independent predictor for longer postoperative stay (β = 2.01, P < .01). Overall, no differences in postoperative complications or 3- to 6-month outcomes were seen by surgical approach., Conclusion: Our international, multicenter matched analysis suggests microscopic approaches for pituitary tumor resection may offer better GTR rates, albeit with increased intensive care unit stay, CSF leak, SIADH, and hospital utilization. Better prospective studies can further validate these findings as matching patients for outcome analysis remains challenging. These results may provide insight into surgical benchmarks at different centers, offer room for further registry studies, and identify best practices., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Hyponatremia is the most common electrolyte disorder, affecting more than 15% of patients in the hospital. Syndrome of inappropriate antidiuresis (SIAD) is the most frequent cause of hypotonic hyponatremia, mediated by nonosmotic release of arginine vasopressin (AVP, previously known as antidiuretic hormone), which acts on the renal V2 receptors to promote water retention. There are a variety of underlying causes of SIAD, including malignancy, pulmonary pathology, and central nervous system pathology. In clinical practice, the etiology of hyponatremia is frequently multifactorial and the management approach may need to evolve during treatment of a single episode. It is therefore important to regularly reassess clinical status and biochemistry, while remaining alert to potential underlying etiological factors that may become more apparent during the course of treatment. In the absence of severe symptoms requiring urgent intervention, fluid restriction (FR) is widely endorsed as the first-line treatment for SIAD in current guidelines, but there is considerable controversy regarding second-line therapy in instances where FR is unsuccessful, which occurs in around half of cases. We review the epidemiology, pathophysiology, and differential diagnosis of SIAD, and summarize recent evidence for therapeutic options beyond FR, with a focus on tolvaptan, urea, and sodium-glucose cotransporter 2 inhibitors., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Endocrine Society.)

Background: Dysnatremia occurs commonly in patients with aneurysmal subarachnoid hemorrhage (aSAH). The mechanisms for development of sodium dyshomeostasis are complex, including the cerebral salt-wasting syndrome, the syndrome of inappropriate secretion of antidiuretic hormone, diabetes insipidus. Iatrogenic occurrence of altered sodium levels plays a role, as sodium homeostasis is tightly linked to fluid and volume management., Methods: Narrative review of the literature., Results: Many studies have aimed to identify factors predictive of the development of dysnatremia, but data on associations between dysnatremia and demographic and clinical variables are variable. Furthermore, although a clear relationship between serum sodium serum concentrations and outcomes has not been established-poor outcomes have been associated with both hyponatremia and hypernatremia in the immediate period following aSAH and set the basis for seeking interventions to correct dysnatremia. While sodium supplementation and mineralocorticoids are frequently administered to prevent or counter natriuresis and hyponatremia, evidence to date is insufficient to gauge the effect of such treatment on outcomes., Conclusions: In this article, we reviewed available data and provide a practical interpretation of these data as a complement to the newly issued guidelines for management of aSAH. Gaps in knowledge and future directions are discussed., (© 2023. Springer Science+Business Media, LLC, part of Springer Nature and Neurocritical Care Society.)

A 31-year-old female presented to the emergency department with abdominal pain, vomiting and constipation. Serum sodium levels were recorded at 110 mmol/L on admission, dropping to 96 mmol/L despite fluid restriction. The patient developed hallucinations and required hypertonic saline administration in critical care. Urinary sodium was detected at 149 mmol/L, consistent with syndrome of inappropriate antidiuretic hormone secretion (SiADH). Urinary porphyrins were also raised, consistent with a diagnosis of acute intermittent porphyria with SiADH as a complication.

Delayed hyponatraemia(DH) is a common complication following trans-sphenoidal surgery(TSS) for pituitary tumour. We evaluated the prevalence of DH following TSS, and assessed the factors associated with DH, including early post-operative diabetes insipidus(EPDI). This retrospective study included 100 TSS for pituitary tumours in 98 patients, over a period of 26 months. Subjects were divided into two groups: those who developed hyponatraemia and those who did not develop hyponatraemia, during post-operative days 4 to 14. The clinical characteristics and peri-operative parameters were compared between the two groups, to identify factors predicting DH. The mean age of the patients was 42.0±13.6 years, 58 (59%) were females and 61 (61%) had functional tumours. Thirty-six patients(36%) developed DH following TSS of whom majority(58%) were diagnosed on post-operative days 7 and 8; only 8/36 (22%) were symptomatic. Syndrome of inappropriate antidiuretic hormone secretion(SIADH) was found to be the most common aetiology of DH. On logistic regression analysis, intra-operative cerebrospinal fluid(CSF) leak (OR 5.0; 95% CI 1.9-13.8; p=0.002), EPDI (OR 3.4; 95% CI 1.3-9.2; p=0.015) and peri-operative steroid use (OR 3.6; 95% CI 1.3-9.8; p=0.014) were found to be significantly associated with DH. In conclusion, EPDI, intra-operative CSF leak and peri-operative steroid use were significant predictors of DH. EPDI predicts moderate to severe hyponatraemia with 80% specificity but has low sensitivity(47%). As most patients have asymptomatic hyponatraemia, serum sodium measurement on POD 7 to 10 would be helpful to identify DH in patients at increased risk., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Objective: Oxytocin (OXT) secretion has been shown to be abnormally elevated in patients who develop syndrome of inappropriate secretion of antidiuretic hormone (SIADH)-related hyponatremia after transsphenoidal pituitary surgery (TPS). While OXT was previously reported to increase natriuresis in the kidney, a potential role for this hormone in postoperative sodium balance and dysnatremias has not been studied. The objective of this study was to analyze the correlation between patients' urinary output of OXT and natremia and natriuresis after TPS., Methods: The authors measured and correlated the urinary output of OXT with natriuresis and natremia in 20 consecutive patients who underwent TPS., Results: The ratio of urinary secretion of OXT between days 1 and 4 showed a strong, significant correlation with patient natriuresis at day 7 after pituitary surgery. Concomitantly, patient natremia showed a moderate, inverted correlation with OXT secretion in the urine., Conclusions: Together, these results show for the first time that urinary OXT secretion correlates with patient natriuresis and natremia after pituitary surgery. This observation suggests a notable role for this hormone in sodium balance.

We report a case of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) after total proctocolectomy followed with ileal pouch-anal anastomosis (TPC-IPAA) for ulcerative colitis (UC). The patient was a 46-year-old woman. She was diagnosed with UC of pancolitis in 2000. High grade dysplasia was detected in the transverse colon after a surveillance colonoscopy in 2021. She underwent laparoscopy-assisted TPC-IPAA. On the sixth postoperative day, she had a decreased level of consciousness that worsened on the following day. Her laboratory data showed a serum sodium level of 108 mEq/L and the plasma osmolality was 234 mOsm/kg. We did not find any other abnormalities in the laboratory examination that could cause hyponatremia. Computed tomography scan showed no central nervous system disturbances such as a pituitary tumor, antidiuretic hormone-producing tumors, or pulmonary diseases. The patient was diagnosed with Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) caused by surgical invasion. We started to administer 3% sodium chloride slowly to improve the hyponatremia. Her serum sodium level became normal and stable. Although it is rare for SIADH to be caused by abdominal surgery, if hyponatremia is observed after surgery, the possibility of postoperative SIADH should be considered., (© 2022. Japanese Society of Gastroenterology.)

A hyponatremic patient with the syndrome of inappropriate antidiuresis (SIAD) gets normal saline (NS), and the plasma sodium decreases, paradoxically. To explain, desalination is often invoked: if urine is more concentrated than NS, the fluid's salts are excreted while some water is reabsorbed, exacerbating hyponatremia. But comparing concentrations can be deceiving. They should be converted to quantities because mass balance is key to unlocking the paradox. The [sodium] equation can legitimately be used to track all of the sodium, potassium, and water entering and leaving the body. Each input or output "module" can be counterbalanced by a chosen iv fluid so that the plasma sodium stays stable. This equipoise is expressed in terms of the iv fluid's infusion rate, an easy calculation called the ratio profile. Knowing the infusion rate that maintains steady state, we can prescribe the iv fluid at a faster rate in order to raise the plasma sodium. Rates less than the ratio profile may risk a paradox, which essentially is caused by an iv fluid underdosing. Selecting an iv fluid that is more concentrated than urine is not enough to prevent paradoxes; even 3% saline can be underdosed. Drinking water adds to the ratio profile and is underestimated in its ability to provoke a paradox. In conclusion, the quantitative approach demystifies the paradoxical worsening of hyponatremia in SIAD and offers a prescriptive guide to keep the paradox from happening. The ratio profile method is objective and quickly deployable on rounds, where it may change patient management for the better., Competing Interests: R. Chiaramonte has ownership interest in BioPharma Credit/Pharmakon, ITB-MED/Zelarion, ProKidney, and Royalty Pharma; patents or royalties with Royalty Pharma; and an advisory or leadership role with ITB-MED/Zelarion. J. Shey reports being an employee of West Coast Kidney Institute and has ownership interest in Fresenius Kidney Care. The remaining author has nothing to disclose., (Copyright © 2022 by the American Society of Nephrology.)

A novel rapid spreading and changing virus called SARS-CoV-2 appeared in Wuhan city in December 2019. It was announced by the World Health Organization (WHO) as a pandemic disease in March 2020. It commonly presents with respiratory symptoms; however, it may be asymptomatic. Electrolyte abnormalities are not uncommon features of SARS-CoV-2 infection. Hyponatremia is one of these electrolyte disturbances among SARS-CoV-2 patients, and it may produce symptoms such as weakness and seizure as the initial presenting symptoms. The underlying mechanism(s) of hyponatremia due to SARS-CoV-2 infection is (are) not established. The aim of this review is to evaluate the possible mechanism of hyponatremia in patients with COVID-19. Understanding and categorizing the hyponatremia in these patients will lead to better treatment and correction of the hyponatremia. A review of the literature between December 2019 and March 2022 was conducted searching for the possible reported mechanism(s) of hyponatremia in SARS-CoV-2. Although SIADH is the commonly reported cause of hyponatremia in SARS-CoV-2 infection, other causes such as diarrhea, vomiting, and kidney salt loss must be considered before SIADH., Competing Interests: All authors have no conflict of interest., (Copyright © 2022 the Author(s). Published by Wolters Kluwer Health, Inc.)

Background: Currently, COVID-19 is becoming one of the most common causes of viral pneumonia worldwide. In the medical literature, very few case reports describe the association between COVID-19 and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) in kidney transplant patients., Methods: A 74-year-old immunocompromised man post-kidney transplant presented with nonspecific symptoms consisting of fatigue, malaise, and anorexia. He was also found to have hyponatremia in the context of pulmonary insults. SIADH in the setting of COVID-19 pneumonia was diagnosed after exclusion of other causes of hyponatremia. He was treated for COVID-19 pneumonia with antiviral therapy, secondary bacterial infection prophylaxis, dexamethasone and ventilatory support in addition to modification of antirejection medications., Results: The patient has improved and his serum sodium normalized with management of primary insult., Conclusions: SIADH should be suspected in transplant patients with COVID-19 pneumonia once they develops hyponatremia. The decision of intravenous fluid administration should be taken carefully in these settings., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Asian patients with metastatic non-small cell lung cancer (NSCLC) have a higher prevalence of epidermal growth factor receptor (EGFR) mutations compared to Caucasians, 30-50% and 15%, respectively. Osimertinib is a tyrosine kinase inhibitor approved as first-line therapy in patients with metastatic NSCLC harboring exon 19 or exon 21 EGFR mutations., Case Presentation: We report a 68-year-old treatment-naïve Asian male patient with metastatic NSCLC harboring an exon 19 deletion mutation of EGFR treated with osimertinib. The patient developed an osimertinib-induced syndrome of inappropriate secretion of antidiuretic hormone (SIADH) after approximately two months of therapy. Following fluid restriction and osimertinib discontinuation, the hyponatremia improved significantly within one week. The patient was started on second-line erlotinib without any signs of hyponatremia after treatment initiation., Conclusion: There is a lack of published data from randomized prospective clinical trials of osimertinib-induced SIADH in metastatic NSCLC. Further studies to evaluate the potential underlying mechanisms are warranted., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: The syndrome of inappropriate secretion of antidiuretic hormone is a disorder characterized by the excess release of antidiuretic hormone and can result in hyponatremia. If managed inappropriately, severe hyponatremia can cause seizures, cerebral edema, and even death. There are various known causes of this inappropriate release of antidiuretic hormone, including malignancy, CNS disorders, and disturbances in the hypothalamic-pituitary-renal axis. However, reports of syndrome of inappropriate secretion of antidiuretic hormone after brachytherapy for prostate cancer are exceedingly rare., Case Presentation: We report a case of symptomatic hyponatremia secondary to the inappropriate secretion of antidiuretic hormone after prostate high-dose rate brachytherapy under general anesthesia in a patient with adenocarcinoma of the prostate., Conclusions: In rare instances, inappropriate secretion of antidiuretic hormone can occur after high-dose rate brachytherapy for prostate cancer. The cause is likely multifactorial, involving pain or discomfort ensuing from the surgical procedure, the general anesthesia or intraoperative drugs administered. However, due to the potential severity of the side effects, timely diagnosis is crucial to ensure prompt, and effective management., (© 2022. The Author(s).)

Background: In patients receiving total parenteral nutrition (TPN), the frequency of hyponatraemia is high. However, the causes of hyponatraemia in TPN have not been elucidated, although diagnosis is required for appropriate therapy. The aim of this study is to describe the aetiology of hyponatraemia in non-critical hospitalised patients receiving TPN., Methods: Prospective multicentre study in 19 Spanish hospitals. Non-critically hyponatraemic patients receiving TPN and presenting hyponatraemia over a 9-month period were studied. Data collected included sex, age, previous comorbidities, and serum sodium levels (SNa) before and following TPN initiation. Parameters for study of hyponatraemia were also included: clinical volaemia, the presence of pain, nausea, gastrointestinal losses, diuretic use, oedema, renal function, plasma and urine osmolality, urinary electrolytes, cortisolaemia, and thyroid stimulating hormone., Results: 162 patients were included, 53.7% males, age 66.4 (SD13.8) years. Volume status was evaluated in 142 (88%): 21 (14.8%) were hypovolaemic, 96 (67.6%) euvolaemic and 25 (17.6%) hypervolaemic. In 111/142 patients the analytical assessment of hyponatraemia was completed. Hypovolaemic hyponatraemia was secondary to GI losses in 10/111 (9%), and to diuretics in 3/111 (2.7%). Euvolaemic hyponatraemia was due to Syndrome of Inappropriate Antidiuretic Hormone secretion (SIADH) in 47/111 (42.4%), and to physiological stimuli of Arginine Vasopressin (AVP) secretion in 28/111 (25.2%). Hypervolaemic hyponatraemia was induced by heart failure in 19/111 (17.1%), cirrhosis of the liver in 4/111 (3.6%)., Conclusions: SIADH was the most frequent cause of hyponatraemia in patients receiving TPN. The second most frequent cause was physiological stimuli of AVP secretion induced by pain/nausea., (Copyright © 2021 SEEN and SED. Published by Elsevier España, S.L.U. All rights reserved.)

We report the case of a 68-year-old man, who presented in emergency care with inarticulate speech. The patient was diagnosed with syndrome of inappropriate antidiuretic hormone (SIADH) associated with pancreatic cancer. All diagnostic criteria for SIADH were met, and cancer of the pancreatic tail was identified by computed tomography. Standard treatment for SIADH includes water restriction, oral NaCl, continuous intravenous infusion of 3% NaCl, and intravenous infusion of furosemide. However, these treatments have varying effectiveness and are difficult for both patients and medical staff. Furthermore, unless treatment of the underlying disease is successful, continued hospitalization is needed and the patient's quality of life is significantly impaired. In this case, hyponatremia improved with this standard treatment, but ascites and edema developed. We treated the patient with tolvaptan due to decreased cardiac function, and symptoms improved rapidly. Although surgery and chemotherapy could not be performed for pancreatic cancer, the SIADH was treated for 7 months without relapse. In summary, a case of SIADH complicated by pancreatic cancer was difficult to control with standard treatment, but responded rapidly to tolvaptan, and outpatient treatment could be continued for a long period. Tolvaptan is useful for the treatment of SIADH associated with cancer.

Rationale: Functional pancreatic neuroendocrine tumors (pNETs) rarely produce vasopressin. Here, we reported a case of pNET producing vasopressin in a 78-year-old man with hyponatremia., Patient Concerns: The patient presented with anorexia approximately 4 years ago, and the laboratory test results indicated hyponatremia. He was hospitalized 3 times subsequently due to anorexia in the past 4 years, during which laboratory tests consistently indicated severe hyponatremia., Diagnosis: Upon admission, his serum osmolarity, urine osmolarity, urine sodium level, and 24-hour urine sodium level was 277 mOsm/kg H2O, 465 mOsm/kg H2O, 82.5 mmol/L, and 140.25 mmol, respectively. Gallium-68-labeled tetraazacyclododecanetetraacetic acid-Dphel-Tyr3-octreotate positron emission tomography-computed tomography showed a high uptake lesion measuring approximately 1 cm in diameter in the pancreatic body, and the possibility of pNET was considered. Besides, laboratory tests showed that adrenocorticotropic hormone, follicle-stimulating hormone, and luteinizing hormone released by the pituitary was insufficient in the case of low levels of cortisol, estradiol, progesterone, and testosterone. Thus, the diagnosis of the syndrome of inappropriate antidiuresis (SIAD) was considered along with hypopituitarism., Interventions: The patient underwent surgery, and pNET was confirmed by pathology examination. The immunohistochemical study showed that the tumor cells were positive for somatostatin receptors 2 and vasopressin., Outcomes: In the last follow-up 17 months after surgery, the patient was in good condition, taking methylprednisolone 4 mg every other day, and had been free of anorexia or hyponatremia episodes., Lessons: This case illustrated the potential ectopic production of vasopressin resulting in SIAD in pNETs, highlighting the adoption of gallium-68-labeled tetraazacyclododecanetetraacetic acid-Dphel-Tyr3-octreotate positron emission tomography-computed tomography and vasopressin immunohistochemical staining in the evaluation of the etiology of SIAD., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Objective: Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a common problem during the postoperative course after pituitary surgery. Although treatment of this condition is well characterized, prevention strategies are less studied and reported. The authors sought to characterize outcomes and predictive factors of SIADH after implementation of routine postoperative fluid restriction for patients undergoing endoscopic transsphenoidal surgery for pituitary adenoma., Methods: In March 2018, routine postoperative fluid restriction to 1000 ml/day for 7 days was instituted for all patients who underwent surgery for pituitary adenoma. These patients were compared with patients who underwent surgery for pituitary adenoma between March 2016 and March 2018, prior to implementation of routine fluid restriction. Patients with preoperative history of diabetes insipidus (DI) or concern for postsurgical DI were excluded. Patients were followed by neuroendocrinologists and neurosurgeons, and sodium levels were checked between 7 and 10 days postoperatively. SIADH was defined by a serum sodium level less than 136 mmol/L, with or without symptoms within 10 days after surgery. Thirty-day readmission was recorded and reviewed to determine underlying reasons., Results: In total, 82 patients in the fluid-unrestricted cohort and 135 patients in the fluid-restricted cohort were analyzed. The patients in the fluid-restricted cohort had a significantly lower rate of postoperative SIADH than patients in the fluid-unrestricted cohort (5% vs 15%, adjusted OR [95% CI] 0.1 [0.0-0.6], p = 0.01). Higher BMI was associated with lower rate of postoperative SIADH (adjusted OR [95%] 0.9 [0.9-1.0], p = 0.03), whereas female sex was associated with higher rate of SIADH (adjusted OR [95% CI] 3.1 [1.1-9.8], p = 0.03). There was no difference in the 30-day readmission rates between patients in the fluid-unrestricted and fluid-restricted cohorts (4% vs 7%, adjusted OR [95% CI] 0.5 [0-5.1], p = 0.56). Thirty-day readmission was more likely for patients with history of hypertension (adjusted OR [95% CI] 5.7 [1.3-26.3], p = 0.02) and less likely for White patients (adjusted OR [95% CI] 0.3 [0.1-0.9], p = 0.04)., Conclusions: Routine fluid restriction reduced the rate of SIADH in patients who underwent surgery for pituitary adenoma but was not associated with reduction in 30-day readmission rate.

Purpose: The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a well-known complication of transsphenoidal pituitary surgery, related to inappropriate secretion of arginine vasopressin (AVP). Its diagnosis is based on hyponatremia, with a peak of occurrence around day 7 after surgery and, to date, no early marker has been reported. In particular, copeptin levels are not predictive of hyponatremia in this case. Oxytocin (OXT) is secreted into the peripheral blood by axon terminals adjacent to those of AVP neurons in the posterior pituitary. Besides its role in childbirth and lactation, recent evidences suggested a role for OXT in sodium balance. The contribution of this hormone in the dysnatremias observed after pituitary surgery has however never been investigated., Methods: We analyzed the urinary output of OXT in patients subjected to transsphenoidal pituitary surgery., Results: While OXT excretion remained stable in patients who presented a normonatremic postoperative course, patients who were later diagnosed with SIADH-related hyponatremia presented with a significantly increased urinary secretion of OXT 4 days after surgery., Conclusion: Taken together, these results show for the first time that urinary OXT output remains normally stable after transsphenoidal pituitary surgery. OXT excretion however becomes abnormally high on or around 4 days after surgery in patients later developing hyponatremia, suggesting that this abnormal dynamics of OXT secretion might serve as an early marker for transsphenoidal surgery-related hyponatremia attributed to SIADH.

Introduction: Syndrome of inappropriate antidiuresis (SIAD) can be a complication of hypothalamus-pituitary surgery. The use of tolvaptan in this setting is not well established, hence the primary aim of this study was to assess the sodium correction rates attained with tolvaptan compared with standard treatments (fluid restriction and/or hypertonic saline). Furthermore, we compared the length of hospital stay in the two treatment groups and investigated the occurrence of overcorrection and side effects including osmotic demyelination syndrome., Methods: We retrospectively reviewed 308 transsphenoidal surgical procedures performed between 2011 and 2019 at our hospital. We selected adult patients who developed post-operative SIAD and recorded sodium monitoring, treatment modalities and outcomes. Correction rates were adjusted based on pre-treatment sodium levels., Results: Twenty-nine patients (9.4%) developed post-operative SIAD. Tolvaptan was administered to 14 patients (median dose 15 mg). Standard treatments were employed in 14 subjects (fluid restriction n=11, hypertonic saline n=1, fluid restriction and hypertonic saline n=2). Tolvaptan yielded higher adjusted sodium correction rates (12.0 mmolL -1 /24h and 13.4 mmolL -1 /48h) than standard treatments (1.8 mmolL -1 /24h, p<0.001, and 4.5 mmolL -1 /48h, p=0.004, vs. tolvaptan). The correction rate exceeded 10 mmolL -1 /24h or 18 mmolL -1 /48h in 9/14 and 2/14 patients treated with tolvaptan, respectively, and in no patient who received standard treatments. No side effects including osmotic demyelination occurred. Tolvaptan was associated with a shorter hospital stay (11 vs. 15 days, p=0.01)., Conclusions: Tolvaptan is more effective than fluid restriction (with or without hypertonic saline) and allows for a shortened hospital stay in patients with SIAD after transsphenoidal surgery. However, its dose and duration should be carefully tailored, and close monitoring is recommended to allow prompt detection of overcorrection., 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. The reviewer ES declared a shared affiliation with one of the authors, GC, to the Editor at time of review., (Copyright © 2021 Indirli, Ferreira de Carvalho, Cremaschi, Mantovani, Sala, Serban, Locatelli, Bertani, Carosi, Fiore, Tariciotti, Arosio, Mantovani and Ferrante.)

Arginine vasopressin (AVP)-mediated osmoregulatory disorders, such as diabetes insipidus (DI) and syndrome of inappropriate secretion of antidiuretic hormone (SIADH) are common in the differential diagnosis for children with hypo- and hypernatremia and require timely recognition and treatment. DI is caused by a failure to concentrate urine secondary to impaired production of or response to AVP, resulting in hypernatremia. Newer methods of diagnosing DI include measuring copeptin levels; copeptin is AVP's chaperone protein and serves as a surrogate biomarker of AVP secretion. Intraoperative copeptin levels may also help predict the risk for developing DI after neurosurgical procedures. Copeptin levels hold diagnostic promise in other pediatric conditions, too. Recently, expanded genotype and phenotype correlations in inherited DI disorders have been described and may better predict the clinical course in affected children and infants. Similarly, newer formulations of synthetic AVP may improve pediatric DI treatment. In contrast to DI, SIADH, characterized by inappropriate AVP secretion, commonly leads to severe hyponatremia. Contemporary methods aid clinicians in distinguishing SIADH from other hyponatremic conditions, particularly cerebral salt wasting. Further research on the efficacy of therapies for pediatric SIADH is needed, although some adult treatments hold promise for pediatrics. Lastly, expansion of home point-of-care sodium testing may transform management of SIADH and DI in children. In this article, we review recent developments in the understanding of pathophysiology, diagnostic workup, and treatment of better outcomes and quality of life for children with these challenging disorders., Competing Interests: POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose., (Copyright © 2021 by the American Academy of Pediatrics.)

A previously well 21-year-old girl presented to Hospital Teluk Intan, Perak, Malaysia with a short history of fever, vomiting and altered sensorium. She was diagnosed with dengue encephalitis as her dengue NS-1 antigen was positive and her cerebrospinal fluid (CSF) dengue polymerase chain reaction (PCR) was positive with serotype DENV-2. She also had severe hyponatremia due to Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) which caused an episode of seizure. She recovered well with supportive management. SIADH and dengue encephalitis should be considered as one of the differential diagnosis in patients presenting with fever and altered sensorium especially in dengue endemic countries like Malaysia.

BACKGROUND Syphilis has increased in prevalence in the United States by 72.7% from 2013 to 2017, with the highest rates recorded in men who have sex with men. There is an increased incidence of syphilis in patients with a concomitant HIV infection, estimated at a 77-fold increase. CASE REPORT This report documents an unusual case of neurosyphilis manifesting as syndrome of inappropriate antidiuretic hormone secretion (SIADH) in a 56-year-old man with HIV/AIDS. A 56-year-old man who has sex with men with HIV/AIDS presented with a 4-day history of periumbilical abdominal pain, nausea, and constipation. A physical exam revealed slowing of baseline cognition, but was otherwise unremarkable. Urine and serum osmolality studies were consistent with SIADH as defined by the Bartter and Schwartz Criteria: serum osmolality <275 mOsm/kg, urine osmolality >100 mOsm/kg, urine sodium >20-40 mmol/L, euvolemia, and no other cause for hyponatremia identified. He was fluid-restricted, with improvement in laboratory abnormalities, further supporting the diagnosis of SIADH. A diagnostic work-up included a CT abdomen/pelvis with perirectal lymphadenopathy, colonoscopy negative for malignancy, chest CT with lymphadenopathy, and a head MRI negative for intracranial processes. The patient was ultimately found to have positive results on rapid plasma reagin (RPR) and Venereal Disease Research Laboratory (VDRL) tests, and was diagnosed as having neurosyphilis. He underwent penicillin desensitization and received a 14-day course of penicillin G, with recovery of sodium to normal range on discharge. CONCLUSIONS Our case highlights SIADH as an initial presenting sign of neurosyphilis with HIV infection, which has only been documented in 2 prior case reports. Our case highlights the importance of recognizing atypical presentations of neurosyphilis in patients with HIV to prevent long-term complications.

Fungal infections involving the pituitary gland are rare and can be life threatening. A 75-year-old man with hypertension and diabetes mellitus presented with headache and hyponatraemia. Imaging study showed right upper lung mass, and mass resection showed aspergilloma without tissue invasion on histology. The patient developed visual impairment a few weeks later, and MRI of the brain revealed bilateral sphenoid sinusitis and pituitary invasion. The trans-sphenoidal biopsy confirmed invasive Aspergillus infection. His sphenoidal sinuses were endoscopically debrided, and he was treated with oral voriconazole. Pituitary aspergillosis should be considered in the differential diagnosis in patients with lung aspergilloma with headache and sinusitis. Prompt biopsy and antifungal treatment are important due to the high mortality rate of the infection., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

A 32-year-old man was found to have a nasal mass on DOTATATE positron emission tomography (PET) scan to investigate the cause of his syndrome of inappropriate antidiuretic hormone secretion (SIADH). The patient presented 6 years earlier with malignant hypertension followed by a second emergency admission for hyponatraemia. Multiple scans and blood tests over 6 years yielded no cause for his SIADH. Nasendoscopy was unremarkable. A PET scan prompted endoscopic sinus surgery which resulted in the resection of a mass in the anterior hiatus semilunaris. The histological findings were fitting with a diagnosis of a neurocytic-type tumour favouring an olfactory neurocytoma. Following resection, the patient remains well and is cured of his SIADH. An olfactory neurocytoma although rare should be considered as a benign differential for a mass in the nasal space. This case demonstrates how an olfactory neurocytoma can present as a cause of SIADH., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Nowadays, humanity faces one of the most serious health crises, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. The severity of coronavirus disease 2019 (COVID-19) pandemic is related to the high rate of interhuman transmission of the virus, variability of clinical presentation, and the absence of specific therapeutic methods. COVID-19 can manifest with non-specific symptoms and signs, especially among the elderly. In some cases, the clinical manifestations of hyponatremia may be the first to appear. The pathophysiological mechanisms of hyponatremia among patients with COVID-19 are diverse, including syndrome of inappropriate antidiuretic hormone secretion (SIADH), digestive loss of sodium ions, reduced sodium ion intake or use of diuretic therapy. Hyponatremia may also be considered a negative prognostic factor in patients diagnosed with COVID-19. We need further studies to evaluate the etiology and therapeutic management of hyponatremia in patients with COVID-19.

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a known cause of hyponatremia, caused by excessive ADH secretion which, in turn, leads to water retention. SIADH has been associated with multiple etiologies, one of which is traumatic brain injury (TBI). Most cases of SIADH after TBI describe a course in which hyponatraemia develops several days to weeks after the trauma and then resolves within a few weeks. We demonstrate a case of SIADH after TBI, which persisted several years after initial presentation, but eventually did resolve spontaneously after five years.

Intravascular lymphomatosis (IVL) is a rare type of B-cell non-Hodgkin lymphoma (BCNHL), which can mimic many other diseases. Fever, neurological symptoms, and skin findings are the most frequent clinical findings. Intravascular lymphomatosis may be associated with genetic factors and infection with human immunodeficiency virus (HIV), human herpesvirus 8 (HHV-8), human T-lymphotropic virus 1 (HTLV1), Epstein-Barr virus (EBV), and hepatitis B virus (HBV). A 50-year-old man was hospitalized with recalcitrant hyponatremia of unknown cause. He had also telangiectatic, indurated, slightly erythematous plaques on his trunk for the last 10 days. His past medical history was unremarkable, although he was a carrier of hepatitis B. Multiple skin biopsies were performed and were considered to be diagnostic of IVL. The hyponatremia was unresponsive to water restriction and hypertonic solution support but it resolved with B cell directed chemotherapy. A final diagnosis was made as syndrome of inappropriate antidiuretic hormone (SIADH) in the setting of IVL. This case had a relatively early diagnosis with just 10-days of skin lesions. Intravascular lymphomatosis is a very rare disease and is usually difficult to diagnose. An even more uncommon presentation is IVL complicated by a paraneoplastic syndrome. There are prior reported cases of SIADH in the setting of IVL. However, this case underscores the importance of evaluating patients with SIADH for potential IVL.

Background: Cerebral salt-wasting syndrome (CSWS), which usually secondary to cerebral diseases, is characterized by hyponatremia and hypovolemia. In clinical practice, it is quite difficult to distinguish CSWS from other hyponatremia syndrome, especially in Intensive Care Unit (ICU) where the conditions of patients are more complicated. Nonetheless, it is crucial because treatments might be fundamentally different., Case Presentation: We discuss a case of patient who presented with refractory hyponatremia and hypovolemia after traumatic brain injury, finally was diagnosed with CSWS, and successfully treated with corticotropin., Conclusions: This case report provides a unique opportunity to observe the trigger of subdural effusion-induced CSWS, and also it provides the classical therapy for CSWS in a critically ill patient. In view of the difficulty to tell CSWS from other similar diseases in ICU, ICU doctors should be aware of such condition., (Copyright © 2020 National Medical Association. Published by Elsevier Inc. All rights reserved.)

Patients with pituitary masses who undergo transsphenoidal resection are at risk for a number of medical complications postoperatively. Among these are disturbances in fluid and sodium homeostasis, including diabetes insipidus (DI) and syndrome of inappropriate secretion of antidiuretic hormone (SIADH). It is believed that these pathologic states are a result of damage to the hypothalamic-pituitary axis from surgery, as are the downstream consequences, such as the triple phase response. The triple-phase response describes the pattern of initial acute DI, subsequent rebound SIADH, and eventual chronic DI, the pathophysiology of which is described. Given the medical complexity of managing postoperative pituitary patients, it is essential to develop dedicated postoperative management protocols. Here, we describe the University of Utah's postoperative pituitary management protocol that includes immediate postoperative monitoring, treatment of DI, surveillance for the triple-phase response after discharge with outpatient serum sodium checks, and involvement of the endocrinology service for assistance with management of hypopituitarism. A complete understanding of the relevant anatomy, physiology, and development of standardized protocols for postoperative management can aid with minimizing medical complications after pituitary surgery., Competing Interests: None