Clinical management of SIADH

Temporal Trends of Hyponatremia in Patients with Respiratory and Intrathoracic Cancers Treated with Chemotherapy and Immune Checkpoint Inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICIs) offer a novel approach to cancer treatment by enhancing immune responses against malignant cells. However, ICIs are associated with immune-related adverse events (irAEs), including hyponatremia, a potentially severe electrolyte disturbance. The risk of hyponatremia increases further when ICIs are combined with cisplatin, a nephrotoxic chemotherapy agent widely used in treating respiratory and intrathoracic cancers. This study investigated the incidence, severity, and temporal dynamics of hyponatremia in patients treated with ICIs alone or in combination with cisplatin.

METHODS

A retrospective cohort study was conducted using data from the TriNetX global health research network. Patients with respiratory or intrathoracic malignancies (n = 14,026) were divided into two groups: ICI-only (n = 7013) and ICI with cisplatin combination (n = 7013), matched using propensity scores. Hyponatremia was categorized into mild (130-134 mmol/L), moderate (125-129 mmol/L), and severe (<125 mmol/L). Temporal trends and cumulative incidence over 90 days were analyzed using Poisson regression.

RESULTS

The combination group exhibited a higher cumulative incidence of hyponatremia across all severity levels, with early-phase risk peaking within 20 days of treatment. Rate ratios for mild, moderate, and severe hyponatremia were significantly elevated in the combination group (p < 0.01).

CONCLUSIONS

Hyponatremia is a significant complication in patients receiving ICIs, particularly when combined with cisplatin. Early monitoring and tailored management are essential to mitigate risks and optimize treatment outcomes.

Ticking Down Sodium Levels-An Atypical Link Between Chronic Hyponatremia and Borreliosis

Lyme disease (LD), caused by the spirochete Borrelia burgdorferi, is the most prevalent tick-borne disease in Europe, including Romania, where endemic areas are well documented. It has a wide range of clinical manifestations and severity, including rare neurological complications. Persistent hyponatremia is an atypical presentation of Lyme neuroborreliosis and can be associated with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). SIADH is characterized by unregulated antidiuretic hormone release, leading to impaired water excretion, dilutional hyponatremia, and low serum osmolality. We report the case of a 16-year-old female with clinically well-tolerated, but severe, refractory hyponatremia, who was poorly responsive to intravenous sodium supplementation and fluid management. Complex investigations ruled out multiple causes of hyponatremia; neuroborreliosis was confirmed via positive Borrelia serologies, despite the absence of a suggestive history of exposure. SIADH likely symptomatology resulted from central nervous system inflammation induced by Borrelia, a mechanism rarely documented in the medical literature. Treatment with antibiotics and fluid restriction led to a gradual improvement in fluid balance and sodium homeostasis. This case emphasizes the importance of considering rare infectious causes, such as LD, in patients with unexplained SIADH, especially in endemic areas. It highlights the importance of a multidisciplinary approach in intricate, complex cases.

Severe hyponatremia secondary to syndrome of inappropriate antidiuretic hormone (SIADH): A rare cause of takotsubo (stress) cardiomyopathy

Takotsubo cardiomyopathy is a reversible, stress-induced systolic abnormality of the left ventricular apex.1,2 It can carry significant morbidity and mortality for patients, largely due to associated complications that can occur in the acute setting. While it is most commonly linked with acute emotional or physical stressors, it is now recognized that many acute medical illnesses can precipitate the syndrome. Severe acute hyponatremia (<120 mmol/L) should be considered as a possible causative condition for Takotsubo cardiomyopathy, however reports of its occurrence in the literature are exceedingly rare.3-14 We present a case of a 73-year-old woman who was admitted for severe hyponatremia secondary to syndrome of inappropriate anti-diuretic hormone (SIADH) with a sodium level of 105 mmol/L and a concomitant diagnosis of Takotsubo cardiomyopathy, as well as a review of the epidemiology, pathophysiology, clinical features, diagnosis, treatment and clinical outcomes of Takotsubo cardiomyopathy.

Syndrome of Inappropriate Antidiuretic Hormone (SIADH) in Chronic Respiratory Diseases: A Comprehensive Review

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a complex and often underdiagnosed disorder characterized by impaired water homeostasis, leading to hyponatremia and associated complications. This comprehensive review explores the intersection of SIADH with chronic respiratory diseases, including chronic obstructive pulmonary disease (COPD), pulmonary tuberculosis, cystic fibrosis, and interstitial lung disease. The review looks at current evidence on pathophysiology, diagnostic challenges, and treatment approaches, highlighting the need for specialized management strategies to improve patient outcomes. Through an analysis of clinical and observational studies, this review highlights the significant impact of SIADH on morbidity and mortality among patients with respiratory diseases. It illustrates the necessity for further research to refine diagnostic and therapeutic modalities.

Ectopic olfactory neuroblastoma is associated with increased frequency of syndrome of inappropriate antidiuretic hormone secretion and reduced disease control: Case series with systematic review and pooled analysis

INTRODUCTION

Olfactory neuroblastoma (ONB) is a rare malignant tumor originating from the olfactory neuroepithelium, typically within the sinonasal cavity. Cases of ONB originating outside of the olfactory cleft area are extremely rare and are referred to as "ectopic" (eONB), in contrast to "orthotopic" tumors (oONB). ONB has been associated with paraneoplastic syndromes (PNSs), including the syndrome of inappropriate antidiuretic hormone secretion (SIADH). This study investigate the association between eONB and SIADH and compared the prognosis of eONB to oONB.

METHODS

A systematic literature review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted, focusing on studies reporting eONB and oONB associated with SIADH. Data from four newly identified eONB cases were reported and a pooled analysis was performed. Statistical analyses were conducted to evaluate the prevalence of SIADH in eONB and oONB and to compare clinical outcomes in the two groups.

RESULTS

eONB had a significantly higher prevalence of SIADH (18.3%) compared to oONB (2.0%; p < 0.0001). Patients with eONB were younger, with a slight predominance of females. Recurrence-free survival and time-to-recurrence of eONB were worse than oONB, independently of other prognosticators.

CONCLUSIONS

eONB is associated with a significantly higher incidence of SIADH than oONB, suggesting distinct biological characteristics. Moreover, patients with eONB had worse prognostic outcomes. Further research is needed to understand the underlying mechanisms and improve management strategies for eONB.

Pain related syndrome of inappropriate antidiuretic hormone secretion in a kitten

A 2-month-old domestic shorthair kitten was presented for evaluation of weakness, gait abnormalities, and signs of pain after trauma. On admission, the patient was found laterally recumbent with obvious gait abnormalities: difficulty rising from sitting and marked unilateral left hind limb lameness. On orthopedic examination, severe pain, crepitations, and swelling of the left hind limb were detected. Results of the first diagnostic work-up were all consistent with hyponatremia, hypochloremia and a Salter-Harris type I fracture. The kitten initially received isotonic fluids, analgesia, and antiemetic treatment. Twelve hours after admission, the analgesic plan was considered insufficient, and the general patient's condition worsened, showing severe mental depression. Blood and urine samples were collected for a more in-depth diagnostic evaluation; the patient showed worsening hyponatremia (113 mmol/L; [RR: 146,2-156,2]), severe plasma hypoosmolality (218.2 mOsm/kg; [RR: 287-307 mOsm/kg]), high natriuresis (Na: 74.9 mmol/L; [RR: <40 mmol/L]), and urinary hyperosmolality (630 mOsm/kg; [RR: <150 mOsm/kg]). Based on these new clinical findings syndrome of inappropriate antidiuretic hormone (SIADH) secretion was diagnosed. Emergency treatment with hypertonic saline was then instituted, a constant rate infusion of 3% hypertonic saline infusion to increase plasma sodium was initiated and a loop diuretic, furosemide (1 mg/kg/IV), was administered at 12-hour intervals to induce diuresis. Discharge occurred 4 days after admission as the patient was clinically stable and the hyponatremia progressively resolved. To the author's knowledge this is the first report of a kitten developing pain related SIADH associated to orthopedic trauma.

Long-term Outcome of a Chihuahua With Idiopathic Syndrome of Inappropriate Antidiuretic Hormone Secretion

An approximately 3 yr old female Chihuahua was presented for evaluation of polyuria and polydipsia noted by the owner after adoption. Serum biochemistry and urinalysis revealed hyponatremia, hypochloremia, hypo-osmolality, and normal fractional excretion of sodium. Serum antidiuretic hormone concentration was 5.54 pg/mL and serum copeptin concentration was 135.40 pg/mL. The antidiuretic hormone value was above the reported range for healthy dogs and was considered inappropriate in light of serum osmolality. Idiopathic syndrome of inappropriate antidiuretic hormone secretion was considered the most likely diagnosis after excluding other potential causes, such as diuretic use, renal disease, adrenal disease, and thyroid dysfunction. The dog remains clinically well 2 yr after diagnosis without specific treatment other than minimal dietary salt supplementation. This case is unique because of the absence of systemic or neurologic signs, good long-term outcome without treatment, and use of novel diagnostic testing.

Acute Management of Moderate to Severe Traumatic Brain Injury

The focus of this article is on the acute management of traumatic brain injury. The article focuses on the classification of traumatic brain injury, general acute management of traumatic brain injury, the role of the physiatrist on this team, and lastly, behavioral and family considerations in the acute care setting. The article includes a focus on physiologic systems, strategies for the management of various aspects of brain injury, and consideration of factors associated with the continuum of care. Overall, the article reviews this critical period of brain injury recovery and provides a primer for the physiatrist.

Suspected cerebral salt wasting syndrome secondary to traumatic brain injury in a dog

OBJECTIVE

To describe a dog with suspected cerebral salt wasting syndrome (CSWS) secondary to traumatic brain injury (TBI).

CASE SUMMARY

A 2-month-old intact male Chihuahua-American Pitbull Terrier mix weighing 1.94 kg presented to a veterinary teaching emergency room after suffering bite wound-penetrating trauma to the head. Treatment was initiated with hyperosmotic agents, fluid resuscitation, and analgesia. The dog's neurologic dysfunction warranted hospitalization and continuous monitoring. Within 24 hours, the dog developed hyponatremia (133 mmol/L compared to 143 mmol/L on presentation [reference interval 142-149 mmol/L]). As the dog had concurrent tachycardia, increase in urine sodium concentration, polyuria, and weight loss, a diagnosis of cerebral salt wasting was suspected. A 2% hypertonic saline constant rate infusion was administered for volume replacement, and the patient showed improvement in clinical signs and blood sodium concentration. The dog was discharged on Day 5. Recheck examination showed significant neurologic improvement with sodium just below the low end of the reference range (141 mmol/L [reference interval 142-149 mmol/L]).

NEW OR UNIQUE INFORMATION PROVIDED

This is the first description of suspected CSWS in veterinary medicine. Hyponatremia is a common finding in critically ill neurologic people, including those with TBI, and is typically associated with either syndrome of inappropriate antidiuretic hormone or CSWS. As treatment recommendations for syndrome of inappropriate antidiuretic hormone and CSWS are diametrically opposed, identifying the presence of hyponatremia and distinguishing between these 2 clinical entities is critical for improving patient care for those with TBI. This case highlights the characteristics and clinical progression regarding the diagnosis and management of suspected CSWS.

Sertraline Hydrochloride Overdose Resulting in Diabetes Insipidus: A Case Report

Sertraline hydrochloride belongs to the selective serotonin reuptake inhibitor class of antidepressants, which can cause respiratory depression, hypotension, malignant vomiting, liver function impairment, and other symptoms when taken in excess. To our knowledge, reports of sertraline hydrochloride overdose causing diabetes insipidus in patients are rare. This report describes a unique case of a 17-year-old female patient who developed diabetes insipidus after a one-time oral intake of 20 sertraline hydrochloride tablets (50 mg/tablet) during the later course of treatment. Her symptoms were effectively relieved after treatment with pituitrin.

Syndrome of inappropriate antidiuretic hormone secretion as an adverse reaction of ciprofloxacin: a case report and literature review

Antidiuretic hormone (ADH) is secreted by the posterior pituitary gland. Unsuppressed release of ADH leads to hyponatremia. This condition is referred to as syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hereby, a case report is presented on ciprofloxacin-induced SIADH. A 67-year-old male patient was examined in the emergency room with symptoms of lethargy, headache, lack of attention, and a generally depressed mood lasting for three days. One week prior, empirical antimicrobial therapy involving ciprofloxacin for prostatitis was initiated. Laboratory analysis showed no relevant abnormalities except for hyponatremia (Na = 129 mmol/L). Chronic hyponatremia, thyroid dysfunction, and adrenal dysfunction were ruled out. Serum osmolality was 263 mOsmol/kg, urine osmolality was 206 mOsmol/kg, and urine sodium was 39 mmol/L. Given that all criteria for SIADH were met, ciprofloxacin was discontinued, and fluid restriction was advised. Four days later, the patient's serum sodium concentrations nearly normalized (Na = 135 mmol/L), and all symptoms resolved. The Naranjo Scale yielded a score of 8, supporting the likelihood of a probable adverse reaction to ciprofloxacin. This case is presented to raise awareness among clinicians about the potential of ciprofloxacin to cause even mild hyponatremia.

Tolvaptan for Treatment of Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) in a Child with Corpus Callosum Agenesis

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is one of the common causes of euvolemic hyponatremia (serum Na+ < 135 mEq/L) in hospitalized children. It is characterized by increased serum ADH, leading to water retention via its action on V2 receptors in the distal renal tubules. Various conditions such as pain, the postoperative state, drugs, central nervous system infections, tumors, malformations, and pneumonia can predispose a person to SIADH. The conventional treatment of SIADH includes fluid restriction and salt supplementation. Occasionally, this may fail to control hyponatremia, mandating pharmacological therapy. V2-receptor antagonists are an FDA-approved therapy for adults with euvolemic and hypervolemic hyponatremia. However, there is limited experience with their use in the pediatric population. Here, the authors present a girl with corpus callosum agenesis with severe symptomatic hyponatremia due to SIADH who was successfully managed with the V2-receptor antagonist tolvaptan.

Long-term low-dose tolvaptan efficacy and safety in SIADH

PURPOSE

Tolvaptan, a selective vasopressin V2-receptor antagonist, is approved for the treatment of SIADH-related hyponatremia, but its use is limited. The starting dose is usually 15 mg/day, but recent clinical experience suggests a lower starting dose (<15 mg/day) to reduce the risk of sodium overcorrection. However, long-term low-dose efficacy and safety has not been explored, so far. Aim of our study is to characterize safety and efficacy of long-term SIADH treatment with low-dose Tolvaptan.

METHODS

We retrospectively evaluated 11 patients receiving low-dose Tolvaptan (<15 mg/day) for chronic SIADH due to neurological, idiopathic and neoplastic causes. Plasma sodium levels were measured before and 1, 3, 5, 15 and 30 days after starting Tolvaptan and then at 3-month intervals. Anamnestic and clinical data were collected.

RESULTS

Mean time spanned 27.3 ± 29.8 months (range 6 months-7 years). Mean plasma sodium levels were within normal range 1, 3 and 6 months after starting Tolvaptan as well as after 1, 2, 3, 5 and 7 years of therapy. Neither osmotic demyelination syndrome nor overcorrection were observed. Plasma sodium levels normalization was associated with beneficial clinical effects. Neurological patients obtained seizures disappearance, improvement in neurological picture and good recovery from rehabilitation. Neoplastic patients were able to start chemotherapy and improved their general condition. Patients did not show hypernatremia during long-term follow-up and reported mild thirst and pollakiuria.

CONCLUSIONS

The present study shows that long-term low-dose Tolvaptan is safe and effective in SIADH treatment. No cases of overcorrection were documented and mild side effects were reported.

Clinical Significance and Management of Hyponatremia in Liver Cirrhosis

The overall prevalence of hyponatremia in cirrhotics is around 50%. Hypovolemic hyponatremia is a result of excessive fluid loss caused mostly by diuretic treatment or diarrhea. More common is hypervolemic hyponatremia, which results from excessive activation of water and sodium-retaining mechanisms caused by effective arterial hypovolemia. This review focuses on the associations of hyponatremia with clinical outcomes and reviews the available data on its management. Hyponatremia is a strong predictor of mortality and is also associated with an increased probability of hepatorenal syndrome, disturbance of consciousness, infections, and unfavorable post-transplant outcomes. In the management of hyponatremia, it is crucial to distinguish between hypovolemic and hypervolemic hyponatremia. The treatment of hypervolemic hyponatremia should be started only in symptomatic patients. The cessation of the treatment with traditional diuretics and fluid restriction may prevent further decrease in natremia. Pharmacological treatment is directed towards cirrhosis itself, precipitating factor, or hyponatremia directly. Currently, only albumin infusions can be recommended routinely. Other possibilities, such as vaptans, splanchnic vasoconstrictors, niravoline, or osmotic diuretics, are restricted to specific use cases (e.g., imminent liver transplantation) or need more research to determine their efficacy. We tried to summarize the management of hyponatremia into a concise flowchart.

Clinical efficacy of urea treatment in syndrome of inappropriate antidiuretic hormone secretion

The aim of this work is to examine our experience in the use of urea in patients with SIADH. Observational retrospective analysis of 48 patients with SIADH that have been treated with urea in a third-level hospital. Pre-post analysis of serum sodium levels. The 48 patients with SIADH had a median age of 78.5 (range 26–97 years). The serum sodium nadir was 119.8 ± 5.0 mmoL/L and at the beginning of treatment 125.6 ± 4.1 mmoL/L. The patients continued the treatment for a mean time of 2.95 ± 6.29 months, being the treatment still active in 4 patients. In all patients there was an improvement in serum sodium, being the final serum sodium at the end of treatment 134.4 ± 4.9 mmoL/L (p < 0.01). This improvement was observed from the first week. Adverse events were only detected in 2 patients with mild digestive symptomatology and 2 patients refused the treatment due to the low palatability of the urea. There was an economic cost reduction of 87.9% in comparison with treatment with tolvaptan. Urea has shown to be a safe and cost-effective option for the treatment of hyponatremia caused by SIADH.

The management and outcome of hyponatraemia following transsphenoidal surgery: a retrospective observational study

Purpose

Hyponatraemia is a common complication following transsphenoidal surgery. However, there is sparse data on its optimal management and impact on clinical outcomes. The aim of this study was to evaluate the management and outcome of hyponatraemia following transsphenoidal surgery.

Methods

A prospectively maintained database was searched over a 4-year period between January 2016 and December 2019, to identify all patients undergoing transsphenoidal surgery. A retrospective case-note review was performed to extract data on hyponatraemia management and outcome.

Results

Hyponatraemia occurred in 162 patients (162/670; 24.2%) with a median age of 56 years. Female gender and younger age were associated with hyponatraemia, with mean nadir sodium being 128.6 mmol/L on postoperative day 7. Hyponatraemic patients had longer hospital stay than normonatraemic group with nadir sodium being inversely associated with length of stay (p < 0.001). In patients with serum sodium ≤ 132 mmol/L, syndrome of inappropriate antidiuretic hormone secretion (SIADH) was the commonest cause (80/111; 72%). Among 76 patients treated with fluid restriction as a monotherapy, 25 patients (25/76; 32.9%) did not achieve a rise in sodium after 3 days of treatment. Readmission with hyponatraemia occurred in 11 cases (11/162; 6.8%) at a median interval of 9 days after operation.

Conclusion

Hyponatraemia is a relatively common occurrence following transsphenoidal surgery, is associated with longer hospital stay and risk of readmission and the effectiveness of fluid restriction is limited. These findings highlight the need for further studies to better identify and treat high-risk patients, including the use of arginine vasopressin receptor antagonists.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00701-022-05134-9.

The management of acute and chronic hyponatraemia

Hyponatraemia is the most common electrolyte abnormality encountered in clinical practice; despite this, the work-up and management of hyponatraemia remain suboptimal and varies among different specialist groups. The majority of data comparing hyponatraemia treatments have been observational, up until recently. The past two years have seen the publication of several randomised control trials investigating hyponatraemia treatments, both for chronic and acute hyponatraemia. In this article, we aim to provide a background to the physiology, cause and impact of hyponatraemia and summarise the most recent data on treatments for acute and chronic hyponatraemia, highlighting their efficacy, tolerability and adverse effects.

Syndrome of inappropriate antidiuretic hormone secretion secondary to trauma in a dog

OBJECTIVE

To describe a case of inappropriate antidiuretic hormone (ADH) secretion in a dog secondary to trauma.

CASE SUMMARY

A 14-year-old neutered female mixed breed dog presented for evaluation of bite wounds. The dog sustained multiple puncture wounds to the cervical area, stifle, and elbow. Treatment was initiated with isotonic crystalloid fluids, analgesia, broad-spectrum antimicrobials, and gastroprotectants. The dog developed hyponatremia with concurrent serum hypoosmolality and inappropriate urine hyperosmolality and urine sodium secretion, leading to a diagnosis of the syndrome of inappropriate ADH secretion. The hyponatremia improved, and the dog improved clinically and was discharged 3 days after admission.

NEW OR UNIQUE INFORMATION PROVIDED

This is the first case description of the syndrome of inappropriate ADH secretion in a dog suffering from trauma. Inappropriate ADH secretion is largely under-recognized in veterinary patients. Increased awareness of this syndrome can lead to initiation of appropriate treatment and improved outcomes.

Asymptomatic meningitis diagnosed by positron emission tomography in a patient with syndrome of inappropriate antidiuretic hormone secretion: a case report

Background

Syndrome of inappropriate antidiuretic hormone secretion can be caused by arginine-vasopressin-producing tumors or enhanced arginine vasopressin secretion from the posterior pituitary gland due to central nervous system disorders and intrathoracic diseases.

Case presentation

A 53-year-old Asian man was hospitalized with complaints of tremor and hiccups. Laboratory examination revealed findings suggestive of hypotonic hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion. The patient did not complain of headache or photophobia, and showed no signs of meningeal irritation. Positron emission tomography–computed tomography revealed 18F-fluoro-deoxy-glucose accumulation along the cervical spinal cord, based on which the patient was diagnosed as having aseptic meningitis. The hyponatremia was treated successfully by fluid restriction, and optimum plasma sodium concentration was maintained by tolvaptan administration.

Conclusions

This case underscores the need to consider the possibility of mild meningitis as the cause of syndrome of inappropriate antidiuretic hormone secretion in patients without other identifiable cause.

Oxcarbazepine-Induced Hyponatremia: A Case Report and Comprehensive Literature Review

Oxcarbazepine is a well-known and effective anti-convulsant used for patients with underlying seizure disorder. It is a structural analog of carbamazepine; however, it follows a different metabolic pathway in which it is converted to a different active metabolite. Side effects associated with this medication are vast; however, in this report, we will hone in on the renal adverse effects, e.g., syndrome of inappropriate anti-diuretic hormone secretion (SiADH). SiADH is a condition in which the body is making too much anti-diuretic hormone, which, in turn, results in "too much" water absorption, causing hyponatremia with neurologic sequelae. Our patient is a 31-year-old gentleman with a history of depression, anxiety, bipolar disorder, and previous suicide attempts who presented to the emergency department following oxcarbazepine overdose and was subsequently found to be hyponatremic secondary to having SiADH.

Hyponatremia and Encephalopathy in a 55-Year-old Woman with Syndrome of Inappropriate Antidiuretic Hormone Secretion as an Isolated Presentation of SARS-CoV-2 Infection

BACKGROUND During the coronavirus disease 2019 (COVID-19) pandemic of 2020, varied presentations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been reported. The present report is of a case of hyponatremia and encephalopathy due to the syndrome of inappropriate antidiuretic hormone secretion (SIADH) as the main presentation of SARS-CoV-2 infection in a 55-year-old woman. CASE REPORT A 55-year-old woman with type II diabetes mellitus presented with confusion and slurring of speech, with a temperature of 38.5°C, heart rate of 120 bpm, blood pressure of 159/81 mmHg, and oxygen saturation of 98% on room air. She did not have edema on examination. Laboratory testing showed a low sodium level of 116 mEq/L (reference range, 135-145 mEq/L) with urine osmolarity of 364 mOsm/kg, urinary sodium of 69 mEq/L, urinary potassium of 15.6 mEq/L, and serum osmolarity of 251 mOsm/kg. The patient had normal serum thyroid-stimulating hormone and cortisol levels. A chest X-ray should no pulmonary infiltrates nor did a lumbar puncture reveal signs of infection. A real-time SARS-CoV-2 polymerase chain reaction assay was positive for COVID-19. Brain imaging with computed tomography was negative for acute infarct, intracranial hemorrhage, and mass effect. Based on findings from laboratory testing and physical examination, a diagnosis of SIADH was made. The patient was treated with 3% hypertonic saline, followed by salt tablets and fluid restriction, with improvement in her clinical symptoms and serum sodium level. CONCLUSIONS The present report is of a rare but previously reported association with SARS-CoV-2 infection. Encephalopathy and hyponatremia associated with SIADH without pneumonia or other symptoms of infection should be an indication for testing for SARS-CoV-2 infection.

Syndrome of inappropriate antidiuretic hormone secretion in a patient with pituitary apoplexy

Pituitary apoplexy (PA) is an endocrine emergency presenting with headache, visual and hormonal disturbances. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is rare after PA. A 64-year-old woman presented with acute frontal headache and nausea with normal neurological examination. Labs included normal sodium and creatinine. Echo showed new-onset congestive heart failure (CHF) and MRI of the brain revealed PA. She had normal cortisol levels and low thyroid stimulating hormone with normal thyroxine (T₄) levels. During her hospitalisation, patient developed hyponatraemia. Initially, this was attributed to CHF and she was treated with tolvaptan with normalisation of sodium. One week later, she was readmitted with diarrhoea and hyponatraemia. She was euvolaemic on examination indicating compensated CHF. Despite fluid challenge, patient had no improvement of sodium levels. The diagnosis of SIADH was made. Clinicians should suspect SIADH in patients with hyponatraemia in the setting of PA with normal T₄ and cortisol levels.

Anticancer Medications and Sodium Dysmetabolism

Therapeutic advances have revolutionised cancer treatment over the last two decades, but despite improved survival and outcomes, adverse effects to anticancer therapy such as dyselectrolytaemias do occur and need to be managed appropriately. This review explores essential aspects of sodium homeostasis in cancer with a focus on alterations arising from anticancer medications. Sodium and water balance are tightly regulated by close interplay of stimuli arising from hypothalamic osmoreceptors, arterial and atrial baroreceptors and the renal juxtaglomerular apparatus. This delicate balance can be disrupted by cancer itself, as well as the medications used to treat it. Some of the conventional chemotherapeutics, such as alkylating agents and platinum-based drugs, can cause hyponatraemia and, on rare occasions, hypernatraemia. Other conventional agents such as vinca alkaloids, as well as newer targeted cancer therapies including small molecule inhibitors and monoclonal antibodies, can cause hyponatraemia, usually as a result of inappropriate antidiuretic hormone secretion. Hyponatraemia can also sometimes occur secondarily to drug-induced hypocortisolism or salt-wasting syndromes. Another atypical but distinct mechanism for hyponatraemia is via pituitary dysfunction induced by immune checkpoint inhibitors. Hypernatraemia is uncommon and occasionally ensues as a result of drug-induced nephrogenic diabetes insipidus. Identification of the aetiology and appropriate management of these conditions, in addition to averting treatment-related problems, can be lifesaving in critical situations.

Impairment of Neurocognitive Functioning, Motor Performance, and Mood Stability in Hospitalized Patients With Euvolemic Moderate and Profound 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.

Evaluation of Hypervolemia in Children

Hypervolemia is a condition with an excess of total body water and when sodium (Na) intake exceeds output. It can have different causes, such as hypervolemic hyponatremia (often associated with decreased, effective circulating blood volume), hypervolemia associated with metabolic alkalosis, and end-stage renal disease. The degree of hypervolemia in critically ill children is a risk factor for mortality, regardless of disease severity. A child (under 18 years of age) with hypervolemia requires fluid removal and fluid restriction. Diuretics are able to increase or maintain urine output and thus improve fluid and nutrition management, but their benefit in preventing or treating acute kidney injury is questionable.

National trends in hospital readmission following transsphenoidal surgery for pituitary lesions

PURPOSE

Several institutions recently published their experiences with unplanned readmissions rates after transsphenoidal surgery for pituitary lesions. Readmission rates on a national level, however, have not been explored in depth. We investigated nationwide trends in this procedure and associated independent predictors, costs, and causes of 30-day readmission.

METHODS

The Nationwide Readmissions Database was queried to identify patients 18 and older who underwent transsphenoidal surgery for pituitary lesion resection (2010-2015). National trends and statistical variances were calculated based on weighted, clustered, and stratified sample means.

RESULTS

Of the weighted total of 44,759 patients treated over the 6-year period, 4658 (10.4%) were readmitted within 30 days. Readmission rates did not change across the survey period (P = 0.71). Patients readmitted had a higher prevalence of comorbidities than those not readmitted (82.5% vs. 78.4%, respectively, P < 0.001), experienced more postoperative complications (47.2% vs. 31.8%, P < 0.001), and had a longer length of stay (6.59 vs. 4.23 days, P < 0.001) during index admission. The most common causes for readmission were SIADH (17.5%) and other hyponatremia (16.4%). Average total readmission cost was $12,080 with no significant trend across the study period (P = 0.25). Predictors for readmission identified included diabetes mellitus, psychological disorders, renal failure, and experiencing diabetes insipidus during the index admission.

CONCLUSION

Unplanned readmission is an important quality metric. While transsphenoidal pituitary surgery is a relatively safe procedure, 30-day readmission rates and costs have not declined. Future studies on institutional protocols targeting these identified predictors to prevent readmission are necessary to decrease readmission rates on a national scale.

Higher incidence of syndrome of inappropriate antidiuretic hormone secretion during induction chemotherapy of acute lymphoblastic leukemia in indian children

BACKGROUND

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a well-known adverse effect of vincristine (VCR). Literature suggests that Asians are predisposed to develop SIADH following VCR administration. However, data regarding the occurrence of SIADH in children with malignancy are limited. This study aims to analyze the incidence, clinical picture, risk factors, management, and outcome of SIADH during induction chemotherapy for pediatric acute lymphoblastic leukemia (ALL).

MATERIALS AND METHODS

A prospective study was conducted among the 166 newly diagnosed pediatric ALL patients who were treated at a tertiary cancer center in India between January 2015 and December 2015. Patients who developed hyponatremia during induction chemotherapy were further investigated for SIADH.

RESULTS

The incidence of SIADH was 10.8% (n = 18) with a mean sodium level of 125 mEq/L (114-129 mEq/L). In the preceding 2 weeks, 72% of episodes were associated with the administration of two (n = 6) or three (n = 7) doses of VCR. One child presented with seizures. All the patients were managed with fluid restriction and only two patients required sodium correction with 3% saline. Girls older than 10 years of age showed a marginally significant correlation to develop SIADH (P-value = 0.059).

CONCLUSION

We report a higher incidence of SIADH (10.8%) in Indian children, compared to that described in the literature, during induction chemotherapy for ALL. Regular monitoring of sodium levels during this period of chemotherapy is hence essential for the timely diagnosis and appropriate management of SIADH, which in turn will avert complications, including neurological symptoms secondary to SIADH.

Clinical Approach to Sodium Homeostasis Disorders in Children with Pituitary-Suprasellar Tumors

Children with pituitary-suprasellar tumors are at high risk of developing sodium metabolism disorders since the tumoral mass itself or surgical and medical treatment can damage AVP release circuits. Additional risk factors are represented by the use of hypotonic fluids, the young age, total parenteral nutrition, and obstructive hydrocephalus secondary to tumor pathology. The most frequent hyponatremic disorders related to AVP in these patients are the syndrome of inappropriate ADH secretion and the cerebral/renal salt wasting syndrome, while hypernatremic conditions include central diabetes insipidus (CDI) and adipsic CDI. The main challenge in the management of these patients is to promptly distinguish the AVP release disorder at the base of the sodium imbalance and treat it correctly by avoiding rapid sodium fluctuations. These disorders can coexist or follow each other in a few hours or days; therefore, careful clinical and biochemical monitoring is necessary, especially during surgery, the use of chemotherapeutic agents, or radiotherapy. This monitoring should be performed by experienced healthcare professionals and should be multidisciplinary, including pediatric endocrinologists, neurosurgeons, and oncologists since maintaining sodium homeostasis also plays a prognostic role in terms of disease survival, therapeutic response, hospitalization rate, and mortality. In this review, we analyze the management of sodium homeostasis disorders in children with pituitary-suprasellar tumors and discuss the main challenges in the diagnosis and treatment of these conditions based on literature data and over 30 years of clinical experience at our Department of Pediatric Endocrinology.

Hyponatremia associated with long-term medication use in the elderly: an analysis in general practice

INTRODUCTION The aim of this study is to determine the prevalence of hyponatremia, its association with long-term medication use and underlying chronic conditions, the rate of hospitalisation and death within 3 months from its discovery and its management in community-dwelling older people. METHODS One year of data for ~5635 patients aged >65 years was extracted from the databases of 19 general practitioners (GPs); 2569 (45.6%) were checked for hyponatremia. RESULTS Hyponatremia occurred in 205 (8.0%) of 2569 checked individuals: 78.5% (161/205) had hypertension, 31.2% (64/205) diabetes, 23.9% (49/205) chronic renal failure; 38.0% (78/205) received diuretics, 36.6% (75/205) renin-angiotensin system antagonists (ACE-I/ARB) and 9.8% (20/205) serotonin reuptake inhibitors. Drug consumption was higher in hyponatremic patients, although only diuretics, ACE-I/ARB, anti-arrhythmics and opioids were significantly associated with hyponatremia. The likelihood of hyponatremia trebled when four drugs were taken, and it was seven-fold higher with the use of six drugs. Hyponatremia was associated with a higher prevalence of chronic illnesses and higher rate of hospitalisation (13.7% vs 7.7%, P = 0.005) and death (3.9% vs 1.8%, P < 0.035). The use of at least one long-term medication was associated with hospitalisation or death in hyponatremic patients (10% vs 6.3%, P = 0.010). Less than 20% of hyponatremic patients had their sodium level checked again after 1 month. DISCUSSION Hyponatremia is not uncommon among community-living older patients, especially in patients taking medications potentially causing hyponatremia. Hyponatremic patients are likely to encounter more serious events, including hospitalisation and death. Targeted training of GPs is desirable to improve their practice.

Equivalent Efficacy and Decreased Rate of Overcorrection in Patients With Syndrome of Inappropriate Secretion of Antidiuretic Hormone Given Very Low-Dose Tolvaptan

Rationale & Objective

Euvolemic hyponatremia often occurs due to the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Vasopressin 2 receptor antagonists may be used to treat SIADH. Several of the major trials used 15 mg of tolvaptan as the lowest effective dose in euvolemic and hypervolemic hyponatremia. However, a recent observational study suggested an elevated risk for serum sodium level overcorrection with 15 mg of tolvaptan in patients with SIADH.

Study Design

A retrospective chart review study comparing outcomes in patients with SIADH treated with 15 versus 7.5 mg of tolvaptan.

Settings & Participants

Patients with SIADH who were treated with a very low dose of tolvaptan (7.5 mg) at a single center compared with patients using a 15-mg dose from patient-level data from the observational study described previously.

Predictors

Tolvaptan dose of 7.5 versus 15 mg daily.

Outcomes

Appropriate response to tolvaptan, defined as an initial increase in serum sodium level > 3 mEq/L, and overcorrection of serum sodium level (>8 mEq/L per day, and >10 mEq/L per day in sensitivity analyses).

Analytical Approach

Descriptive study with additional outcomes compared using t tests and F-tests (Fischer's Exact χ2 Test).

Results

Among 18 patients receiving 7.5 mg of tolvaptan, the mean rate of correction was 5.6 ± 3.1 mEq/L per day and 2 (11.1%) patients corrected their serum sodium levels by >8 mEq/L per day, with 1 of these increasing by >12 mEq/L per day. Of those receiving tolvaptan 7.5 mg, 14 had efficacy, with increases ≥ 3 mEq/L; similar results were seen with the 15-mg dose (21 of 28). There was a statistically significant higher chance of overcorrection with the use of 15 versus 7.5 mg of tolvaptan (11 of 28 vs 2 of 18; P = 0.05; and 10 of 28 vs 1 of 18; P = 0.03, for >8 mEq/L per day and >10 mEq/L per day, respectively).

Limitations

Small sample size, retrospective, and nonrandomized.

Conclusions

Tolvaptan, 7.5 mg, daily corrects hyponatremia with similar efficacy and less risk for overcorrection in patients with SIADH versus 15 mg of tolvaptan.

Tolvaptan-induced Liver Injury: Who is at Risk? A Case Report and Literature Review

Hyponatremia is a common clinical condition encountered in the hospital setting. Syndrome of inappropriate antidiuretic hormone (SIADH) is an important and one of the most common causes of hyponatremia. SIADH accounts for approximately one-third of all cases of hyponatremia. Tolvaptan is a vasopressin receptor antagonist used to treat SIADH. Hepatoxicity is a rare yet dangerous side effect from Tolvaptan use. We present a case of cholestatic liver injury in an elderly female who presented with hyponatremia. She received two doses of tolvaptan 15mg and developed worsening in her total bilirubin (T Bili) and alkaline phosphatase (Alk Phos) levels. Tolvaptan is known to cause elevated transaminase levels and the mechanism of action is thought to be idiosyncratic. Fortunately, the patient responded with an improvement in T Bili and Alk Phos levels after stopping tolvaptan. This case highlights the cautious use of tolvaptan in elderly patients with SIADH as even small doses can potentiate hepatotoxicity. 

Somatostatin Receptor Ligand Therapy-A Potential Therapy for Neurocytoma

CONTEXT

Neurocytoma (NC) is a rare, low-grade tumor of the central nervous system, with a 10-year survival rate of 90% and local control rate of 74%. However, 25% of NCs will be atypical, with an elevated Ki-67 labeling index >2%, and will exhibit a more aggressive course, with a high propensity for local recurrence and/or craniospinal dissemination. Although no standard treatment regimen exists for these atypical cases, adjuvant stereotactic or conventional radiotherapy and/or chemotherapy have been typically offered but have yielded inconsistent results.

CASE DESCRIPTION

We have described the case of a patient with a vasopressin-secreting atypical NC of the sellar and cavernous sinus region. After subtotal resection via endoscopic transsphenoidal surgery, the residual tumor showed increased fluorodeoxyglucose uptake and high somatostatin receptor (SSTR) expression on a 68Ga-DOTA-TATE positron emission tomography/CT scan. Somatostatin receptor ligand (SRL) therapy with lanreotide (120 mg every 28 days) was initiated. Four years later, the residual tumor was stable with decreased fluorodeoxyglucose tumor uptake. Immunocytochemical SSTR2 and SSTR5 expression >80% was further confirmed in a series of NC tissues.

CONCLUSIONS

To the best of our knowledge, we have described the first use of SRL therapy for an atypical NC. Our results support consideration of adjuvant SRL therapy for NC refractory to surgical removal. Our findings further raise the possibility of SSTR-directed peptide receptor radionuclide therapy as NC therapy.

Hydration, Arginine Vasopressin, and Glucoregulatory Health in Humans: A Critical Perspective

Glucoregulatory diseases, such as type 2 diabetes are currently a key public health priority. Public health messages have started to include the addition of water in their dietary guidelines. Such guidelines however are not based on causal evidence pertaining to the health effects of increased water intake, but rather more heavily based upon non-causal or mechanistic data. One line of thinking linking fluid intake and health is that hypohydration induces elevated blood concentrations of arginine vasopressin (AVP). Research in the 1970s and 1980s implicated AVP in glucoregulation, supported by observational evidence. This important area of research subsequently appeared to stop until the 21st century during which interest in hypertonic saline infusion studies, animal AVP receptor knockout models, dietary and genetic associations, and human interventions manipulating hydration status have resurged. This narrative review briefly describes and critically evaluates the usefulness of the current AVP-glucoregulatory research. We offer suggestions on how to test the independent glucoregulatory effects of body water changes compared to elevated circulating AVP concentrations, such as investigating hydration manipulations using 3,4-Methylenedioxymethamphetamine. Whilst much research is still needed before making firm conclusions, the current evidence suggests that although AVP may be partially implicated in glucoregulation, more ecologically valid models using human participants suggests this effect might be independent of the hydration status. The key implication of this hypothesis if confirmed in future research is that manipulating the hydration status to reduce circulating AVP concentrations may not be an effective method to improve glucoregulatory health.

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) and Subsequent Central Diabetes Insipidus: A Rare Presentation of Pituitary Apoplexy

Pituitary apoplexy (PA) is a rare endocrine emergency that occasionally presents with sodium disturbances. Here we present a rare case with a previously healthy 41-year-old female who presented with acute onset headache and nausea without visual impairment or overt pituitary dysfunction. Plasma sodium concentrations declined abruptly during the first two days of admission to a nadir of 111 mmol/l. Urine and blood chemistry were consistent with syndrome of inappropriate antidiuretic hormone secretion (SIADH). Magnetic resonance imaging revealed recent bleeding into a pituitary cystic process. Hyponatremia was successfully corrected with fluid restriction and both visual function and anterior pituitary function remained intact. Subsequently, the patient developed central diabetes insipidus (CDI), which responded well to desmopressin substitution. To our knowledge, this is the first case of PA presenting predominantly with posterior pituitary dysfunction that transitioned from SIADH to permanent CDI.

Significance of Hyponatremia as an Independent Factor in Predicting Short-term Mortality in Patients with Hemorrhagic Stroke

Introduction

Hyponatremia is the most common electrolyte imbalance in patients with acute cerebrovascular insults. In patients with acute non-traumatic hemorrhagic stroke, the role of hyponatremia as a negative prognostic indicator has been controversial. The aim of this study is to evaluate the frequency of hyponatremia in patients with hemorrhagic stroke and determine its impact on their in-hospital disease outcome.

Methods

This was a prospective observational study, which included all patients with non-traumatic hemorrhagic stroke. Serum sodium concentration <135 mmol/L was labeled as hyponatremia. The etiology of hyponatremia was determined as syndrome of inappropriate antidiuretic hormone (SIADH) and cerebral salt wasting syndrome (CSWS). The outcome was categorized as “complete recovery,” “motor/sensory deficit but not wheelchair/bed bound,” “wheelchair/bed bound,” and “in-hospital mortality.” SPSS for Windows version 22.0 (IBM Corp., Armonk, NY, US) was used to analyze the data.

Results

Out of 234 patients of hemorrhagic stroke, 45.3% (n=106) were hyponatremic, 58.5% had SIADH and 41.5% had CSWS. The overall mortality rate of hemorrhagic stroke was 16.2%. The mortality rate was 36.5% in the SIADH group, 50% in the CSWS group, and 13.1% in the normonatremic group (p<0.00001). The mean hospital stay in the SIADH group was 7.04 ± 2.57, in the CSWS group, it was 6.50 ± 1.55, and in the normonatremic group, it was 3.88 ± 2.74 (p=0.000).

Conclusion

Hyponatremia is an independent predictor of short-term mortality in patients with acute hemorrhagic stroke.

Investigation and management of moderate to severe inpatient hyponatraemia in an Australian tertiary hospital

BACKGROUND

Hyponatraemia is the most common electrolyte disturbance amongst hospitalised patients. Both American and European guidelines recommend fluid restriction as first line treatment for SIADH, however differ on second line recommendations. The objective of this study was to examine investigation and management of hyponatraemia in hospitalised patients in an Australian tertiary hospital.

METHODS

A retrospective audit was conducted of electronic medical records and laboratory data of inpatients with serum sodium (Na) ≤125 mmol/L, admitted over a 3 month period to the Princess Alexandra Hospital, Brisbane, Australia. The main outcomes measured included: demographic characteristics, investigations, accuracy of diagnosis, management strategy, change in Na and patient outcomes.

RESULTS

The working clinical diagnosis was considered accurate in only 37.5% of cases. Urine Na and osmolality were requested in 72 of 152 patients (47.4%) and in 43 of 70 euvolaemic patients (61.4%). Thyroid function tests (67.1%) and morning cortisol (45.7%) were underutilized in the euvolaemic group. In the SIADH cohort, fluid restriction resulted in a median (IQR) 7.5 mmol/L (4-10.5) increase in Na after 3 days; no treatment resulted in a median 0 mmol/L (- 0.5-1.5) change. Oral urea was utilized in 5 SIADH patients where Na failed to increase with fluid restriction alone. This resulted in a median 10.5 mmol/L (3.5-13) increase in Na from baseline to day 3. There were no cases of osmotic demyelination. The median length of stay was 8 days (4-18.5). Mortality was 11.2% (17 patients). There was a weak but significant correlation between nadir serum Na and mortality (R = 0.18, P = 0.031).

CONCLUSION

Inpatient hyponatraemia is often inadequately investigated, causing errors in diagnosis. Treatment is heterogeneous and often incorrect. In cases with hyponatraemia refractory to fluid restriction, oral urea presents an effective alternative treatment.

SIADH with Severe Hyponatremia in an Elderly Man with Herpes Zoster Infection: A Causal or Casual Association?

Syndrome of inappropriate antidiuretic hormone (SIADH) secretion is the most common cause of hypotonic hyponatremia in hospitalized patients. An elderly man with severe symptomatic hyponatremia (109 mEq/L) was diagnosed with SIADH that was likely secondary to large cutaneous herpes zoster (HZ) infection. Hypertonic saline and tolvaptan improved the patient's sodium levels and clinical condition. A one month after discharge, tolvaptan was withdrawn, due to inadequate prescription criteria, after which hyponatremia relapsed several times and was properly treated; eventually fever and sopor occurred and the patient died. SIADH secondary to HZ may induce life-threatening and long-lasting hyponatremia, which requires a prompt diagnosis and treatment.

Influenza A: another cause of SIADH?

The syndrome of inappropriate antidiuretic hormone (SIADH) secretion is a frequent cause of hyponatraemia. It is a dilutional hyponatraemia secondary to impaired urinary dilution in the absence of renal disease or any identifiable non-osmotic stimulus known to induce antidiuretic hormone secretion. SIADH can arise secondary to various respiratory tract infections; however, the association between SIADH and influenza A infection is described in only a few cases in the literature. The authors present a case report of influenza A that may have caused a profound SIADH-related hyponatraemia.

Severe Symptomatic Hyponatremia Secondary to Escitalopram-Induced SIADH: A Case Report with Literature Review

Hyponatremia is a well-known medication related side effect of selective serotonin reuptake inhibitors; despite its association with escitalopram, the newest SSRI is very rare. We did a review of literature and came across only 14 reported case of this rare association of SIADH with escitalopram. We hereby report a case of a 93-year-old female who presented with generalized tonic-clonic seizure and was diagnosed with severe hyponatremia due to escitalopram-induced syndrome of inappropriate antidiuretic hormone secretion (SIADH). With this article, we want to emphasize clinicians about this rare side effect of escitalopram use and look for the risk factors leading to SIADH.

Hyponatremia Complicating Esophageal Carcinoma: A Challenging Differential Diagnosis

Hyponatremia is a common complication of cancer and of cancer therapy. Awareness of the many causes of hyponatremia in this setting is critical for ordering the appropriate diagnostic tests, instituting the appropriate treatment, and assessing prognosis of the disorder. This case report highlights the challenges in identifying the cause of hyponatremia in some oncology settings and how misdiagnosis can delay appropriate therapy.

From renal salt wasting to SIADH

Hyponatraemia is common following major head injury and is associated with significant morbidity and mortality. A 20-year-old man presented with reduced consciousness after head trauma and was found to have a fractured skull base with bilateral frontal contusions. On day 3 of his admission, he developed hyponatraemia with raised urine sodium and osmolality, despite receiving dexamethasone and intravenous fluid therapy. His hyponatraemia worsened after the treatment with fluid restriction and oral salt. He was in negative fluid balance suggesting possible renal salt wasting. A trial of isotonic normal saline resulted in a further fall in serum sodium level. He was subsequently treated for suspected syndrome of inappropriate ADH with a hypertonic (3%) saline infusion. His sodium level and neurological status improved. This case report illustrates the confounding factors that commonly affect clinical decision-making when treating patients with hyponatraemia following head injury. The guidelines for diagnosis and management are discussed.

Basaloid Squamous Cell Carcinoma of the Lung Associated With Syndrome of Inappropriate Antidiuretic Hormone Secretion

Basaloid squamous cell carcinoma (BSQCC) of the lung is a very rare subtype of squamous cell carcinoma (SCC). There have been no reported cases of syndrome of inappropriate anti-diuretic hormone secretion (SIADH) developing concurrently with this tumor. We herein present a case of a 68-year-old female who was diagnosed with lung mass discovered incidentally on preoperative clearance for surgical fixation of right humeral neck fracture. The patient presented to the hospital with nausea, vomiting, diarrhea and fatigue. Sodium level on admission was 115 mmol/L. Further workup confirmed a diagnosis of BSQCC of the lung and SIADH.

Hyponatremia - A rare complication of Gitelman's syndrome

Gitelman's syndrome (GS) is a rare autosomal recessive disorder caused by mutations in thiazide-sensitive NaCl cotransporter. We report a 49-year-old, normotensive lady with prolonged hypokalemia since her 20s who was diagnosed with GS at our renal clinic. During follow-up, she was found to have mild, asymptomatic, euvolemic hyponatremia with low serum uric acid, inappropriately high urine osmolality and sodium consistent with syndrome of inappropriate antidiuretic hormone-like presentation. Despite life-long urinary sodium losses, hyponatremia has rarely been reported in GS to be due to the primary disease process. We present relevant clinical data and hypothesize on why this disease per se may be a risk factor for dilutional hyponatremia.

Anoxic Brain Injury Secondary to Metabolic Encephalopathy

PURPOSE

To discuss the clinical case of a patient suffering visual dysfunction secondary to a metabolic brain injury, the patient's visual rehabilitative treatment, and outcomes.

CASE REPORT

A 24-year-old Caucasian male presented to the Southern Arizona Veteran's Affairs Healthcare System's Traumatic Brain Injury (TBI) eye clinic for evaluation and treatment of visual dysfunction secondary to an anoxic brain injury suffered 4 months before. Symptoms included persistent right homonymous hemianopia, oculomotor dysfunction, and a visual information processing deficit. After 5 weeks of vision rehabilitation, the patient was reassessed and displayed significant improvement in both signs and symptoms.

CONCLUSIONS

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a metabolic syndrome that causes hyponatremia and, in severe cases, encephalopathy and anoxic brain injury. Damage to the visual pathways can produce visual field, ocular motility, and binocular vision deficits. Comprehensive treatment including rehabilitative vision therapy bolstering the natural neuroplasticity process can provide improvements in patients' quality of life.

Yield of workup for patients with idiopathic presentation of the syndrome of inappropriate antidiuretic hormone secretion

PURPOSE

To determine the proportion of patients for whom the syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the presenting symptom of an underlying disorder, to describe the yield of different diagnostic modalities for patients with SIADH and an unknown etiology, and to define patients for whom such a workup is indicated.

METHODS

A single center retrospective study including all patients diagnosed with SIADH without an apparent etiology in a large community hospital and tertiary center between 1.1.07 and 1.1.13. Two physicians reviewed every patient's medical file for predetermined relevant clinical data.

RESULTS

Eleven of the 99 patients without an apparent etiology for SIADH at presentation were found to have an underlying cause on workup. Yield of performed workup was low, with a pathology demonstrated on 0%-30.8% of tests according to the different modalities used. Patients with presumed idiopathic SIADH at presentation who were later found to have a specific etiology were younger than patients with true idiopathic SIADH, had a significantly shorter duration of hyponatremia prior to SIADH diagnosis, had higher urine osmolality and a clinical presentation suggestive of an undiagnosed disorder.

CONCLUSIONS

Our findings support a clinically-based approach to patients with idiopathic SIADH, rather than an extensive routine workup for all patients.

A case report on acute severe hyponatraemia following parathyroid surgery for primary hyperparathyroidism-A rare but life threatening complication

INTRODUCTION

Parathyroidectomy is a common operation, which is well tolerated and associated with low morbidity. Patients are usually discharged within 24hours of surgery. Severe postoperative hyponatraemia is a rare complication which can cause significant morbidity including seizure, coma, respiratory arrest and even death.

PRESENTATION OF CASE

We present two patients with clinically significant hyponatremia resulting in seizures and collapse within 24hours after parathyroidectomy, an unreported complication following surgery for primary hyperparathyroidism. One patient required support on the High Dependency Unit and both were treated with fluid restriction which resulted in correction of their electrolyte balance.

DISCUSSION

We believe this was caused by the relative inability to secrete a water load after surgery and non-psychogenic polydipsia. Preoperatively, neither patient was prescribed any routine medications nor did they have any risk factors for hyponatremia. Both had normal preoperative sodium levels. It is usual practice is to advise patients to increase oral water intake when they are hypercalcaemic. The aim of parathyroidectomy is to treat hypercalcaemia by stopping excess PTH secretion from abnormal parathyroid glands. These patients continued to follow this advice after surgery when they were eucalcaemic after their operation and because they were thirsty. The patients drank several litres of water in 12-24hours after surgery. We believe that this may have contributed to this complication.

CONCLUSION

Healthcare professionals need to be aware of this complication and patients should be advised to restrict intake of free water after surgery.

The Trafficking of the Water Channel Aquaporin-2 in Renal Principal Cells-a Potential Target for Pharmacological Intervention in Cardiovascular Diseases

Arginine-vasopressin (AVP) stimulates the redistribution of water channels, aquaporin-2 (AQP2) from intracellular vesicles into the plasma membrane of renal collecting duct principal cells. By this AVP directs 10% of the water reabsorption from the 170 L of primary urine that the human kidneys produce each day. This review discusses molecular mechanisms underlying the AVP-induced redistribution of AQP2; in particular, it provides an overview over the proteins participating in the control of its localization. Defects preventing the insertion of AQP2 into the plasma membrane cause diabetes insipidus. The disease can be acquired or inherited, and is characterized by polyuria and polydipsia. Vice versa, up-regulation of the system causing a predominant localization of AQP2 in the plasma membrane leads to excessive water retention and hyponatremia as in the syndrome of inappropriate antidiuretic hormone secretion (SIADH), late stage heart failure or liver cirrhosis. This article briefly summarizes the currently available pharmacotherapies for the treatment of such water balance disorders, and discusses the value of newly identified mechanisms controlling AQP2 for developing novel pharmacological strategies. Innovative concepts for the therapy of water balance disorders are required as there is a medical need due to the lack of causal treatments.