Clinical practice. The syndrome of inappropriate antidiuresis

Severe hyponatremia in a mild COVID-19 patient: diagnostic challenges of SIADH and adrenal insufficiency

This case report presents a 57-year-old Japanese woman with mild COVID-19 who developed severe symptomatic hyponatremia and altered consciousness, notably without pneumonia or central nervous system infection. Initial findings, including low plasma osmolality, high urine osmolality, and elevated IL-6 levels, suggested that the syndrome of inappropriate antidiuretic hormone secretion (SIADH) was the primary cause of her hyponatremia. While initial saline infusion offered temporary symptom relief, sodium levels remained unstable, leading to intermittent steroid therapy. Her improvement with steroids, alongside additional hormonal testing, raised the possibility of partial adrenal insufficiency as a complicating factor. Although secondary adrenal insufficiency in COVID-19 cases has been previously reported, its exact contribution to hyponatremia remains unclear. This case underscores the diagnostic complexities in managing hyponatremia associated with COVID-19, as SIADH is often the leading cause but may not fully explain persistent cases unresponsive to standard treatments. The report also emphasizes the importance of considering adrenal insufficiency in similar cases, particularly given COVID-19's potential impact on the hypothalamic-pituitary-adrenal axis. This case highlights the need for further research into COVID-19's effects on hormonal regulation, as such disruptions may play a key role in COVID-19-related electrolyte imbalances.

Balanced electrolyte solution with 1% glucose as intraoperative maintenance fluid in infants: a prospective study of glucose, electrolyte, and acid-base homeostasis

BACKGROUND

Optimal composition and infusion rates of intravenous maintenance fluids for children undergoing surgery are not well defined. Avoidance of hypoglycaemia, ketosis, and hyponatraemia is important, and current guidelines recommend isotonic fluids containing 1.0-2.5% glucose. However, evidence for its safe use in infants is insufficient. The aim of this study was to investigate whether normoglycaemia is maintained in infants using a balanced electrolyte maintenance infusion with 1% glucose.

METHODS

Infants 1-12 months of age undergoing surgery were included in this prospective two-centre study. Intravenous maintenance fluid was given with infusion rates of 4-8 ml kg-1 h-1. Blood gas and ketone body analysis were performed at induction and at the end of anaesthesia. Plasma glucose concentration was monitored intraoperatively.

RESULTS

For the 365 infants included in this study, the median infusion rate of maintenance fluid was 3.97 (interquartile range 3.21-5.35) ml kg-1 h-1. Mean plasma glucose concentration increased from 5.3 mM at induction to 6.1 mM at the end of anaesthesia (mean difference 0.8 mM; 95% confidence interval 0.6-0.9, P<0.001). No cases of hypoglycaemia (<3.0 mM) occurred. Mean sodium concentration remained stable during anaesthesia. Chloride and ketone body concentration increased and base excess decreased, but these were within the normal range.

CONCLUSIONS

In infants undergoing surgery, maintenance infusion with a balanced electrolyte solution containing 1% glucose, at rates similar to those proposed by Holliday and Segar is a safe alternative with regards to homeostasis of glucose, electrolytes, and acid-base balance.

CLINICAL TRIAL REGISTRATION

ACTRN12619000833167.

Treatment with antidepressant drugs and hyponatremia: a network meta-analysis

OBJECTIVE

To evaluate the risk of hyponatremia during therapy with antidepressant drugs, in particular by investigating whether there is a different risk profile depending on the class or single active principles.

METHODS

A meta-analysis was performed including all studies in which the risk of hyponatremia in subjects with or without antidepressant treatment was assessed. An extensive Medline, Embase and Cochrane search was performed, to retrieve all studies published up to February 5th 2024, using the following words: hyponatremia and antidepressant.

RESULTS

Of 409 retrieved articles, 10 studies satisfied the inclusion criteria encompassing a total of 1,026,870 patients with 89,403 hyponatremic subjects. Treatments with selective serotonin reuptake inhibitors (OR = 3.31 [2.41;4.56], p < 0.01), serotonin-noradrenaline reuptake inhibitors (OR = 5.79 [1.27;26.49], p = 0.02) and tricyclic antidepressants (OR = 3.01 [1.27;7.14], p = 0.01) were found to be significantly associated with an increased risk of hyponatremia, whereas treatment with noradrenaline and specific serotonergic antidepressants was not. A network meta-analysis indicated that treatments with venlafaxine (OR = 5.99 [2.39;14.99], p < 0.01), paroxetine (OR = 4.93 [2.01;12.12], p < 0.01), sertraline (OR = 4.15 [1.98;8.70], p < 0.01), citalopram (OR = 3.49 [1.54;7.9], p < 0.01), escitalopram (OR = 3.49 [1.49;8.19], p < 0.01), fluoxetine (OR = 3.40 [1.13;10.21], p = 0.03) and mirtazapine (OR = 2.83 [1.16;6.92], p = 0.02) were found to be significantly associated with an increased risk of hyponatremia with a progressively decreasing OR. Clomipramine (OR = 4.50 [0.97;20.93], p = 0.05) also showed a trend towards a greater risk of hyponatremia. Otherwise, treatments with fluvoxamine, imipramine, maprotiline, amitriptyline and mianserin were not associated with an increased risk of hyponatremia.

CONCLUSIONS

These data appear useful on clinical grounds, in order to increase the awareness regarding the possibility that antidepressants induce hyponatremia and to encourage regular serum sodium monitoring.

Functioning neuroendocrine tumors (NET): Minimum requirements for a NET specialist

INTRODUCTION AND AIMS

Functioning neuroendocrine tumors (f-NETs) represent a minority of all NETs, however their management is challenging due to the impact on patients' survival and quality of life. In addition to f-NETs, paraneoplastic syndromes (PNS) are due to substances that are not related to the primary anatomical site, they can develop in different phases of NETs evolution, and might complicate the patient's clinical course. Dedicated guidelines are still scanty. We aim to review available literature on f-NETs to propose a useful tool for clinicians in order to improve the diagnostic process and the management.

METHODS

Narrative review focused on f-NETs.

RESULTS

The most common f-NETs include insulinomas, gastrinomas and carcinoid syndrome (CS)- associated NETs. Symptoms related to hormone production may overlap with other common endocrine and gastrointestinal disorders, highlighting the pivotal role of multidisciplinary management. Somatostatin analogs (SSAs) represent the gold standard first-line treatment of most f-NETs, often followed by or combined with other treatments (surgery, liver-directed therapies, targeted therapies, peptide receptor radionuclide therapy). Paraneoplastic syndromes can develop in different phases of NET evolution and might complicate the patient's clinical course and response to therapy.

CONCLUSIONS

The management of hormonal syndromes is challenging and must be based on the multidisciplinary approach. Herein, we pointed out the minimal requirements for a NET specialist in the diagnosis and treatment of f-NETs. Efforts should be made to improve the awareness of functioning forms, to understand their pathogenesis and to improve their management.

Clinical factors associated with hyponatremia correction during treatment with oral urea

BACKGROUND

Oral urea is being used more commonly to treat hyponatremia, but factors contributing to the correction rate are unknown. We hypothesized that clinically relevant factors can be identified to help guide hyponatremia correction with oral urea.

METHODS

This was a retrospective study in two university hospitals including hospitalized patients with hyponatremia (plasma sodium <135 mmol/L) treated with oral urea. Linear mixed-effects models were used to identify factors associated with hyponatremia correction. Rates of overcorrection, osmotic demyelination and treatment discontinuation were also assessed.

RESULTS

We included 161 urea treatment episodes in 140 patients (median age 69 years, 46% females, 93% syndrome of inappropriate antidiuresis). Oral urea succeeded fluid restriction in 117 treatment episodes (73%), was combined with fluid restriction in 104 treatment episodes (65%) and was given as the only treatment in 27 treatment episodes (17%). A median dose of 30 g/day of urea for 4 days (interquartile range 2-7 days) increased plasma sodium from 127 to 134 mmol/L and normalized hyponatremia in 47% of treatment episodes. Older age (β 0.09, 95% CI 0.02-0.16), lower baseline plasma sodium (β -0.65, 95% CI -0.78 to -0.62) and higher cumulative urea dose (β 0.03, 95% CI -0.02 to -0.03) were independently associated with a greater rise in plasma sodium. Concurrent fluid restriction was associated with a greater rise in plasma sodium only during the first 48 h of treatment (β 1.81, 95% CI 0.40-3.08). Overcorrection occurred in 5 cases (3%), no cases of osmotic demyelination were identified and oral urea was discontinued in 11 cases (11%) due to side effects.

CONCLUSION

During treatment with oral urea, older age, higher cumulative dose, lower baseline plasma sodium and initial fluid restriction are associated with a greater correction rate of hyponatremia. These factors may guide clinicians to achieve a gradual correction of hyponatremia with oral urea.

Lactic Acidosis and Electrolyte Disturbances Associated With Hypertriglyceridemia in an Adolescent Receiving Chemotherapy for Acute Lymphoblastic Lymphoma

Given the association of lactic acidosis with inadequate tissue perfusion and poor clinical outcomes, an aggressive investigation and alterations in supportive and therapeutic care are needed for patients with lactic acidosis. However, other etiologies of lactic acidosis may exist, including disorders of excessive production or inadequate clearance. Several of these fall under the category known as "type B" lactic acidosis. We present a 17-year-old female with acute lymphoblastic leukemia who was admitted to the pediatric intensive care unit (PICU) for evaluation of lactic acidosis and severe hyponatremia. Subsequent evaluation argued against pathologic etiologies of lactic acidosis, leading to the conclusion that the high lactic acid laboratory value was caused by hypertriglyceridemia.

Severe Hyponatremia as a Complication of Sepsis: A Case Report

Severe infections such as pneumonia can cause hyponatremia. This phenomenon is widely attributed to the syndrome of inappropriate antidiuretic hormone secretion (SIADH), although the mechanism is not fully understood. Healthcare providers must identify and treat the cause of low sodium correctly to prevent elevated morbidity and mortality. This report describes an uncommon case of severe hyponatremia in a 26-year-old male with no known medical history and no risk factors for immunosuppression. He presented with worsening body pain and shortness of breath, and he noted an ulcerated lesion on his lower back that had drained purulent fluid in the past week. Laboratory studies revealed severe hyponatremia, with a sodium level of 117 mEq/L, and chest X-ray depicted bilateral interstitial opacities concerning for pneumonia. The patient was started on normal saline, empiric antibiotics, and bilevel positive airway pressure in the emergency department. He was admitted to the intensive care unit (ICU) and subsequently required intubation. After a prolonged ICU course, the patient eventually made a full recovery with no residual deficits. Our report demonstrates an uncommon case of severe hyponatremia in a young, previously healthy patient. He presented with alarmingly low sodium levels, likely secondary to SIADH in the setting of sepsis due to skin abscess and pneumonia. The severity of the patient's hyponatremia was a fundamental factor in identifying the critical nature of his disease and the need for expeditious treatment. Familiarity with appropriate management of hyponatremia is crucial for emergency physicians.

Pathophysiology, symptoms, outcomes, and evaluation of hyponatremia: comprehension and best clinical practice

This review article series on water and electrolyte disorders is based on the 'Electrolyte Winter Seminar' held annually for young nephrologists in Japan. The seminar includes lively discussions based on cases, which are also partly included in this series as self-assessment questions. The first article in this series focuses on pathophysiology, symptoms, outcomes, and evaluation of hyponatremia, a common water and electrolyte disorder in clinical practice. Diagnosing the root cause(s) of hyponatremia can be challenging due to various etiologies and co-morbidities that affect water and electrolyte homeostasis, which can result in inappropriate management and worse outcomes in acute and chronic hyponatremia. This review provides an overview of pathophysiology, symptoms, outcomes, and evaluation of hyponatremia for better comprehension and improved clinical practice.

Metabolically stable apelin analogs: development and functional role in water balance and cardiovascular function

Apelin, a (neuro) vasoactive peptide, plays a prominent role in controlling water balance and cardiovascular functions. Apelin and its receptor co-localize with vasopressin in magnocellular vasopressinergic neurons. Apelin receptors (Apelin-Rs) are also expressed in the collecting ducts of the kidney, where vasopressin type 2 receptors are also present. Apelin and vasopressin interact at the brain and renal levels to maintain body fluid homeostasis by regulating diuresis in opposite directions. Apelin and angiotensin II have opposite effects on the regulation of blood pressure (BP). Angiotensin II, by binding to AT1 receptors present in VSMCs, induces intracellular calcium mobilization and vasoconstriction, while apelin, by binding to Apelin-R present on vascular endothelium, increases nitric oxide production and induces vasodilation. Apelin also plays a crucial role in the regulation of cardiac function. Apelin-deficient and Apelin-R-deficient mice develop progressive myocardial dysfunction with ageing and are susceptible to heart failure in response to pressure overload. Since the half-life of apelin is very short in vivo (in the minute range), several metabolically stable apelin analogs and non-peptidic Apelin-R agonists have been developed, with potential applications in diverse diseases. In this review, we highlight the interaction between apelin and vasopressin in the regulation of water balance and that between apelin and angiotensin II in the regulation of BP. Additionally, we underline the protective effects of apelin in cardiac function. Lastly, we discuss the beneficial effects of Apelin-R activation in different pathological states such as hyponatremia, hypertension, and heart failure.

Simultaneous Occurrence of Hyponatremia and Hypokalemia in a Patient with Herpes Zoster: A Case Report with a Review of the Literature

We herein report a patient with herpes zoster (HZ), severe hyponatremia, and hypokalemia. Syndrome of inappropriate antidiuresis (SIAD) leads to euvolemic hyponatremia and hypoosmotic plasma due to inadequate diuresis. Hyponatremia in the current patient was caused by SIAD and associated with HZ of the trigeminal facial nerve (V1). The patient also had hypokalemia, with excessive urinary potassium excretion and elevated cortisol levels. Hypokalemia is caused by hypercortisolemia, which is stimulated by HZ pain. Adequate treatment for HZ and comprehensive pain control play pivotal roles in improving SIAD, cortisol hypersecretion, and the subsequent electrolyte abnormalities.

Sodium and Water Disorders

The balancing of fluids and electrolytes is a core function of the kidneys. There are redundant mechanisms within the body to sense the adequacy of organ perfusion and the composition of body fluids aimed at maintaining hemodynamics and protecting an environment for optimal cellular function. Sodium and water are key components of extracellular fluid and are regulated in response to end-organ perfusion and serum tonicity. Baroreceptors activate the renin-angiotensin-aldosterone system, sympathetic nervous system, vasopressin, and atrial natriuretic peptide to adjust sodium handling to alter extracellular volume. Osmoreceptors affect anti-diuretic hormone release and aquaporin activity in the medullary collecting duct to modify the handling of water. Disordered handling of sodium and/or water may be adaptive or maladaptive, and understanding the stimuli and responses to clinical scenarios assists clinicians in developing appropriate treatment strategies.

Syndrome of inappropriate antidiuresis/hyponatremia in COVID-19

Hyponatremia is the most frequent electrolyte alteration among hospitalized patients and it has been reported in 20-40% of patients with SARS-CoV-2 (COVID-19) infection. Multiple causes of hyponatremia have been hypothesized in these patients. The syndrome of inappropriate antidiuresis (SIAD) has been considered one of the main reasons leading to hyponatremia in this condition. SIAD can be secondary to cytokines release, in particular IL-6. Positive pressure ventilation can be another cause of hyponatremia due to SIAD. Other possible etiologies of hyponatremia in COVID-19 patients can be related to secondary hypocortisolism, nausea, vomiting, heart and kidney damage. Similar to many other clinical conditions, there is strong evidence that hyponatremia is associated with a worse prognosis also in patients with COVID-19 infection. In particular, hyponatremia has been identified as an independent risk of ICU transfer, need of non-invasive ventilation and death. Hyponatremia in COVID-19 patients is in principle acute and symptomatic and should be treated as such, according to the published guidelines. Therefore, patients should be initially treated with i.v. hypertonic saline (3% NaCl) infusion and serum [Na+] should be frequently monitored, in order to remain within a safe rate of correction. There is evidence showing that serum [Na+] correction is associated with a better outcome in different pathologies, including COVID-19 infection.

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.

Why do patients with cancer die?

Cancer is a major cause of global mortality, both in affluent countries and increasingly in developing nations. Many patients with cancer experience reduced life expectancy and have metastatic disease at the time of death. However, the more precise causes of mortality and patient deterioration before death remain poorly understood. This scarcity of information, particularly the lack of mechanistic insights, presents a challenge for the development of novel treatment strategies to improve the quality of, and potentially extend, life for patients with late-stage cancer. In addition, earlier deployment of existing strategies to prolong quality of life is highly desirable. In this Roadmap, we review the proximal causes of mortality in patients with cancer and discuss current knowledge about the interconnections between mechanisms that contribute to mortality, before finally proposing new and improved avenues for data collection, research and the development of treatment strategies that may improve quality of life for patients.

Urea transporter UT-A1 as a novel drug target for hyponatremia

Hyponatremia is the most common disorder of electrolyte imbalances. It is necessary to develop new type of diuretics to treat hyponatremia without losing electrolytes. Urea transporters (UT) play an important role in the urine concentrating process and have been proved as a novel diuretic target. In this study, rat and mouse syndromes of inappropriate antidiuretic hormone secretion (SIADH) models were constructed and analyzed to determine if UTs are a promising drug target for treating hyponatremia. Experimental results showed that 100 mg/kg UT inhibitor 25a significantly increased serum osmolality (from 249.83 ± 5.95 to 294.33 ± 3.90 mOsm/kg) and serum sodium (from 114 ± 2.07 to 136.67 ± 3.82 mmol/L) respectively in hyponatremia rats by diuresis. Serum chemical examination showed that 25a neither caused another electrolyte imbalance nor influenced the lipid metabolism. Using UT-A1 and UT-B knockout mouse SIADH model, it was found that serum osmolality and serum sodium were lowered much less in UT-A1 knockout mice than in UT-B knockout mice, which suggest UT-A1 is a better therapeutic target than UT-B to treat hyponatremia. This study provides a proof of concept that UT-A1 is a diuretic target for SIADH-induced hyponatremia and UT-A1 inhibitors might be developed into new diuretics to treat hyponatremia.

Mortality predictors of patients diagnosed with severe hyponatremia in the emergency department

PURPOSE

To determine the factors affecting mortality as a result of the analysis of the demographic and clinical characteristics and laboratory parameters of patients whose serum Na value was determined to be 125 mEq/L or below at the time of admission to the emergency department (ED).

METHOD

Patients over 18 years of age who admitted to the ED of a tertiary hospital between September 2021 and September 2022 and whose serum sodium level was determined to be 125 mEq/L and below were included in the study. Demographic and clinical characteristics, admission complaints, medications used, Charles comorbidity index (CCI), laboratory parameters, and outcomes of the patients included in the study were recorded in the data form.

RESULTS

Three hundred ninety-nine patients were included in the study. When the 30-day mortality of the patients is examined, the mortality rate was found to be 21.6%. In the analyses performed for the predictive power of laboratory parameters for mortality, it was determined that the highest predictive power among the predictive values determined by the area under the curve (AUC) was the albumin level (AUC 0.801, 95% CI 0.753-0.849, p < 0.001). In the binary logistic regression analysis, urea and albumin were independent predictors of 30-day mortality.

CONCLUSION

According to study data, albumin and urea levels are independent predictors of 30-day mortality in patients diagnosed with severe hyponatremia in the emergency department.

Hyponatremia, hypernatremia and impairment of functional, psychological and sexual domains

OBJECTIVE

To determine the influence of serum sodium on physical, psychologic and sexual function.

METHODS

This is a cross-sectional survey on 3340 community-dwelling men aged 40-79 years from a prospective cohort study in eight European countries, the European Male Ageing Study (EMAS). Participants filled-out the Short Form-36 (SF-36), the Physical Activity Scale for the Elderly (PASE), and the EMAS sexual function questionnaire. For all the analyses, serum sodium corrected for glycaemia ([Na+]G) was used.

RESULTS

The relationship between [Na+]G and SF-36 physical function score (F = 3.99; p = 0.01), SF-36 mental health score (F = 7.69; p < 0.001), and PASE score (F = 14.95; p < 0.001) were best described by a quadratic equation, with worse scores for [Na+]G in either the lowest or the highest ends of the range. After dividing the sample into [Na+]G < 136 mmol/L (n = 81), 136-147 mmol/L (n = 3223) and > 147 mmol/L (n = 36), linear regression analyses with linear spline functions adjusted for confounders did not confirm these relationships. Similarly, erectile dysfunction and [Na+]G, were in a quadratic relationship (F = 9.00; p < 0.001). After adjusting for confounders, the linear regression with spline functions denoted a significantly worsened erectile function for increases in serum [Na+]G > 147 mmol/L (B = 0.15 [0.04;0.26], p < 0.01) but no relationship with [Na+]G < 136 mmol/L. Likewise, the relationship of [Na+]G with concerns about sexual dysfunction was confirmed only for men with serum [Na+]G > 147 mmol/L.

CONCLUSIONS

This is the first study supporting an association between [Na+]G and sexual function. A worsening of erection and concerns about sexual function were observed for the highest values of [Na+]G, independently of other relevant factors.

Worldwide productivity and research trend of publications concerning SIAD: a bibliometric study

Background

Syndrome of inappropriate antidiuretic(SIAD) occurs secondary to various diseases, which is characterised by hypotonic hyponatremia and impaired urinary diluting capacity. Research on SIAD in both domestic and international contexts has a long history. This study objectively and comprehensively analyses the research trends, hotspots and development of SIAD research of the past 20 years using the method of bibliometric analysis.

Methods

The 2003-2022 data in the Web of Science Core Collection database were searched. The Bibliometrix software package, VOSviewer and CiteSpace were used to mine, extract and visualise the retrieved literature, and the generated maps were used in analysing the main topics and trends in the field of SIAD research.

Results

A total of 1215 articles published in 623 journals were included in the analysis, with a total of 18,886 citations. Results showed that the research output on SIAD has continuously increased in the past 20 years, and the United States had the highest number of publications and citations. Keywords with the highest burst strength in recent years were the most mentioned keywords, in addition to the search terms 'hyponatremia', 'covid-19', and 'mortality'. Thus, the relationship among SIAD, covid-19 and mortality may become research frontiers and trends. Fifteen milestone articles were identified through co-citation analysis, which mainly focused on the pathophysiology and treatment of SIAD.

Conclusion

Based on bibliometric analysis and knowledge mapping, this study summarises development trends in the field of SIAD research, providing references for current and future research into SIAD.

[Dysnatremias - concepts and clinical work-up]

Osmotic gradients over cell membranes lead to water movement into or out of cells. An intact osmoregulation prevents osmotic gradients, thereby protecting cells from swelling or shrinking. Na+ is the major cation in the extracellular fluid (ECF) and the major determinant of the osmolarity in the ECF, including plasma. Therefore, the plasma-Na+ concentration needs to be tightly regulated. An excess of electrolyte-free water decreases the concentration of osmolytes leading to hyponatremia. In contrast, a free water deficit increases the osmolyte concentration leading to hypernatremia. Pathophysiology-oriented approaches to dysnatremic patients help both clinicians and patients. Therapeutic interventions depend on the differentiation between acute and chronic, asymptomatic, and symptomatic dysnatremia, and on the patient's extracellular volume status. The therapeutic armamentarium for hyponatremia consists of water restriction, hypertonic infusions, urea, V2 receptor-blockers, and sodium-glucose cotransporter 2 (SGLT2) inhibitors. Patients with hypernatremia are treated with electrolyte-free water or hypotonic sodium-containing solutions depending on their volume status. Basic concepts in the management of dysnatremic patients are discussed.

Dyselectrolytemia in Children With Severe Pneumonia: A Prospective Study

Background Pneumonia is a condition characterized by inflammation of the lung parenchyma. It is one of the leading causes of mortality in children below five years of age. While predominantly prevalent in developing countries, it is also associated with significant healthcare-associated costs in developed countries. Among the many risk factors for childhood pneumonia, incomplete immunization, nonexclusive breastfeeding for less than six months, delayed weaning, poor household air quality, malnutrition, and low birth weight are the most commonly found. Electrolyte disturbances, also known as dyselectrolytemia, have been associated with a broad spectrum of acute infections, including pneumonia, particularly hyponatremia. It occurs in the majority of community-acquired pneumonia. Hyper- and hypokalemia are less frequently occurring electrolyte disturbances. Electrolyte disturbances are due to impairment of the intrarenal mechanism of urine dilution due to extracellular fluid volume depletion and inappropriate secretion of antidiuretic hormone. The central nervous system is imminently affected by acute hyponatremia. This condition frequently culminates in cerebral edema, a result of the rapid fluid shift, and causes sudden fatality. Aim of the study This study aims to study dyselectrolytemia in children with severe pneumonia. Objectives The study objectives are to assess dyselectrolytemia in children with severe pneumonia and to correlate dyselectrolytemia with morbidity and hospital stay. Methodology  This prospective study was conducted on 80 children in the age group of two months up to five years who visited our tertiary care center and had severe pneumonia. We evaluated the extent of dyselectrolytemia in our study population by analyzing the frequency correlation of different kinds of electrolyte imbalances. We also analyzed the correlation between morbidity and hospital stay. Results Out of 80 children in this study with severe pneumonia, 47 (59%) had electrolyte imbalance. Among the patients with electrolyte imbalance, 31 (39%) patients had hyponatremia followed by hypokalemia in 12 (15%) patients, hypernatremia in 3 (4%) patients, and hyperkalemia in 1 (1%) patient. Among the 17 (21%) children with pneumonia requiring ICU admission, 16 (94%) had dyselectrolytemia and 4 (24%) experienced fatal outcomes. Conclusions The majority of the children who were admitted to the ICU had severe pneumonia along with electrolyte imbalance. This necessitates the monitoring of the electrolyte and nutritional status of the patients with pneumonia. Providing proper nutrition advice for children with pneumonia may reduce morbidity and mortality. Early detection and treatment of electrolyte imbalances in pneumonia cases can decrease prolonged hospital stays, ICU admissions, and the need for mechanical ventilation, ultimately contributing to a reduction in morbidity and mortality.

[Consensus recommendations on the diagnosis and treatment of hyponatremia from the Austrian Society for Nephrology 2024]

Hyponatremia is a disorder of water homeostasis. Water balance is maintained by the collaboration of renal function and cerebral structures, which regulate thirst mechanisms and secretion of the antidiuretic hormone. Measurement of serum-osmolality, urine osmolality and urine-sodium concentration help to diagnose the different reasons for hyponatremia. Hyponatremia induces cerebral edema and might lead to severe neurological symptoms, which need acute therapy. Also, mild forms of hyponatremia should be treated causally, or at least symptomatically. An inadequate fast increase of the serum sodium level should be avoided, because it raises the risk of cerebral osmotic demyelination. Basic pathophysiological knowledge is necessary to identify the different reasons for hyponatremia which need different therapeutic procedures.

Tolvaptan and urea in paediatric hyponatraemia

BACKGROUND

The syndrome of inappropriate antidiuretic hormone (SIADH) is usually treated with fluid restriction. This can be challenging in patients with obligate fluid intake for nutrition or medication. Pharmaceutical treatment with tolvaptan and urea is available but minimal paediatric data are available. We review the efficacy and safety of tolvaptan and urea in paediatric patients with SIADH.

METHODS

Retrospective review of paediatric inpatients with clinical diagnosis of SIADH. Patients were identified from pharmacy records based on tolvaptan and urea prescriptions. Relevant information was extracted from patient electronic records. The main outcome measures included the number of days to sodium normalisation, the daily change in plasma sodium concentration, and the maximum increase of plasma sodium concentration in 24 h. Reported side effects were captured.

RESULTS

Thirteen patients received tolvaptan and six urea. Five patients had both agents (tolvaptan converted to urea). Tolvaptan led to plasma sodium normalisation in 10/13 (77%) within 6 days (median 2.5 days, range [1, 6]), with a median change of sodium concentration of 7 mmol/L (- 1, 14) within the first 24 h of treatment. Three patients experienced a change in plasma sodium > 10 mmol/l/day but had no apparent side effects. Urea led to sodium normalisation in 5/6 (83%) patients. The median number of days to normalisation with urea was 2 (1, 10) with a median change of plasma sodium concentration of 2 mmol/L (- 1, 6) within the first 24 h. All patients tolerated tolvaptan and/or urea without unexpected side effects.

CONCLUSIONS

Tolvaptan and urea appear to be safe and effective when fluid restriction is challenging in paediatric SIADH. A higher resolution version of the Graphical abstract is available as Supplementary information.

Paraneoplastic neurologic manifestations of neuroendocrine tumors

Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors arising from the transformation of neuroendocrine cells in several organs, most notably the gastro-entero-pancreatic system and respiratory tract. The classification was recently revised in the 5th Edition of the WHO Classification of Endocrine and Neuroendocrine Tumors. NENs can rarely spread to the central or peripheral nervous systems. Neurologic involvement is determined by the rare development of paraneoplastic syndromes, which are remote effects of cancer. Mechanisms depend on immunologic response to a tumor, leading to the immune attack on the nervous system or the production of biologically active ("functioning") substances, which can determine humoral (endocrine) effects with neurologic manifestations. Paraneoplastic neurologic syndromes (PNS) are immunologically mediated and frequently detected in small cell lung cancer but rarely seen in other forms of NEN. PNS and Merkel cell carcinoma is increasingly reported, especially with Lambert Eaton myasthenic syndrome. Endocrine manifestations are found in a wide spectrum of NENs. They can develop at any stage of the diseases and determine neurologic manifestations. Patient outcomes are influenced by tumor prognosis, neurologic complications, and the severity of endocrine effects.

Acid base homeostasis and serum bicarbonate concentration in syndrome of inappropriate anti-diuretic hormone secretion (SIADH) with hyponatremia

The Syndrome of Inappropriate ADH secretion (SIADH) presents with excess ADH release caused by a range of conditions; including pneumonia, brain tumors, certain lung cancers, and diseases of the hypothalamus. It presents with significant reduction in both sodium and chloride concentrations in the blood. However, reports examining the acid base status indicate a normal serum bicarbonate concentration and systemic acid base homeostasis. The mechanisms for the absence of abnormalities in acid base homeostasis remain speculative. This mini review is highlighting the recent advances in renal molecular physiology to provide answers for the maintenance of acid base status and serum bicarbonate in a physiological range.

A rare case of concomitant Lambert-Eaton myasthenic syndrome and syndrome of inappropriate antidiuretic hormone secretion in a patient with small cell lung carcinoma

Small cell lung carcinoma (SCLC) is a neuroendocrine carcinoma with a poor prognosis and is a common cause of paraneoplastic syndromes. Paraneoplastic syndromes are characterized by neurological and endocrinological problems in patients with malignancy and are often associated with difficulty in induction of chemotherapy. Here we report the case of a patient with SCLC concomitant with two paraneoplastic syndromes, syndrome of inappropriate antidiuretic hormone secretion (SIADH) and Lambert-Eaton myasthenic syndrome (LEMS), who was treated with a platinum-doublet chemotherapy regimen. A 66-year-old male patient presented with a 1-month history of progressive proximal muscle weakness, ataxia gait and 5 kg of body weight loss. The laboratory tests revealed hyponatremia due to SIADH and the existence of antibodies against P/Q-type voltage-gated calcium channels. The nerve conduction study showed a low amplitude of compound muscle action potential (0.38 mv), a 34% decrement on 3-Hz stimulation, and a 1939% increment after maximum voluntary contraction in 10 seconds (7.75 mv). The endobronchial ultrasound transbronchial needle aspiration biopsy revealed the pathological findings of SCLC. A 2-cycle chemotherapy regimen of irinotecan plus cisplatin resulted in temporary tumor shrinkage that lasted 2 months, but the improvement of proximal muscle weakness and hyponatremia were maintained over the tumor re-progression period after chemotherapy. Although paraneoplastic syndromes accelerate the decrease in performance status, chemotherapy for SCLC may improve symptoms related to paraneoplastic syndromes and could be considered in similar cases.

Effect of tolvaptan on hyponatremia in a dog with syndrome of inappropriate secretion of antidiuretic hormone

A 1-year-old spayed female Miniature Schnauzer had chronic hyponatremia, accompanied by polyuria and polydipsia. Blood tests and urinalysis revealed severe hyponatremia, low plasma osmolality with euvolemia, and increased sodium excretion in urine. Hypothyroidism and hypoadrenocorticism were ruled out as causes. These findings led to the diagnosis of syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Magnetic resonance imaging (MRI) showed dilation of the lateral ventricles, indicating severe hydrocephalus. Tolvaptan, a vasopressin V2 receptor antagonist commonly used in human SIADH, was administered along with water restriction. This treatment resulted in a consistent increase in plasma sodium levels without any adverse effects. This case report represents the first documented evidence of the therapeutic efficacy of tolvaptan in treating SIADH in a dog.

The prevalence and outcomes of hyponatremia in children with COVID-19 and multisystem inflammatory syndrome in children (MIS-C)

Introduction

To assess the prevalence of hyponatremia among pediatric patients with coronavirus disease 2019 (COVID-19) and Multisystem Inflammatory Syndrome in Children (MIS-C) and determine if pediatric hyponatremia was associated with an increased length of stay, higher rates of mechanical ventilation, and/or elevated inflammatory markers on admission as compared to eunatremic patients.

Methods

Electronic health records were retrospectively analyzed for 168 children less than 18 years old with COVID-19 or MIS-C who were admitted to pediatric units within the Northwell Health system. The primary exposure was hyponatremic status (serum sodium <135 mEq/L) and the primary outcomes were length of stay, mechanical ventilation usage and increased inflammatory markers.

Results

Of the 168 children in the study cohort, 95 (56%) were admitted for COVID-19 and 73 (43.5%) for MIS-C. Overall, 60 (35.7%) patients presented with hyponatremia on admission. Patients with hyponatremia had higher rates of intensive care unit admission when compared to eunatremic patients (32/60 [53.3%] vs. 39/108 [36.1%], p = 0.030). In regression models, hyponatremia was not significantly associated with increased length of stay or mechanical ventilation rates. After adjustment for relevant confounders, hyponatremia remained associated with an increased square root CRP (β = 1.79: 95% CI: 0.22-3.36) and lower albumin levels (β = -0.22: 95% CI: -0.42--0.01).

Conclusion

Hyponatremia is common in pediatric COVID-19 and MIS-C. Hyponatremia was associated with a lower albumin and higher square root CRP levels. This may suggest an association of inflammation with lower serum sodium levels.

Does hyponatremia pose a risk factor for hip fractures in the elderly? Can a primary physician prevent it?

Objective

Fracture around the hip is amongst the most common and serious fractures in the elderly, which leads to significant morbidity and mortality. In literature, many authors noted that even mild hyponatremia adversely affects bone, leading to an increased incidence of fractures. We aim to determine whether chronic hyponatremia (>90-day duration) increases the risk of hip fracture in the elderly and whether primary care physicians can help to prevent it.

Materials and Methods

During the period from January 2020 to March 2022, we identified 145 patients aged between 65 and 90 years who were admitted to the hospital with hip fractures following a fall and compared them with 140 healthy controls. We recorded sodium (Na) serum levels in all included patients at the time of arrival and consequently for 3 days and compared them with those of controls. Logistic regression was used to calculate odds ratios (ORs). We measured serum Na levels for 3 days and took the average to ascertain hyponatremia.

Result

In the study, the odds of hyponatremia were 70.3% with a confidence interval of 95% versus 3.6% in controls (P = 0.05). Age and hyponatremia were strongly associated with hip fractures following a fall. With a 5-year increase in age, the univariate OR for hip fracture increased by 5.67 (P < 0.0001). After adjusting for age, cases were nearly six times more likely to be hyponatremic than controls (OR = 4.90, P = 0.04).

Conclusion

In our study, we noted that even mild chronic hyponatremia in old age increased the chance of falls. Addressing hyponatremia in the elderly may reduce the risk of falls and minimize hip fractures.

Relapsing Syndrome of Inappropriate Antidiuretic Hormone Production Responding to Tolvaptan Treatment in a Patient With a Micronodular Formation of the Posterior Pituitary Gland

The syndrome of inappropriate ADH-secretion (SIADH) is a common cause of low sodium levels with diverse aetiology. Here, we report a case of a 41 years old male patient diagnosed with SIADH and a good response to Tolvaptan therapy. Of interest, as a potential unique cause, magnetic resonance imaging revealed a micronodular structure in the posterior pituitary, while no other common cause of SIADH could be identified. Hence, to the best of our knowledge, this is the first case of a Tolvaptan-responsive SIADH associated with a pituitary micronodular structure.

Safety and Efficacy of Vaptans in the Treatment of Hyponatremia from Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH): A Systematic Review and Meta-Analysis

The utilization of vasopressin receptor antagonists, known as vaptans, in the management of hyponatremia among patients afflicted with the syndrome of inappropriate antidiuretic hormone (SIADH) remains a contentious subject. This meta-analysis aimed to evaluate the safety and efficacy of vaptans for treating chronic hyponatremia in adult SIADH patients. Clinical trials and observational studies were identified by a systematic search using MEDLINE, EMBASE, and Cochrane Database from inception through September 2022. The inclusion criteria were the studies that reported vaptans' safety or efficacy outcomes compared to placebo or standard therapies. The study protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO; CRD 42022357307). Five studies were identified, comprising three RCTs and two cohort studies, enrolling a total of 1840 participants. Regarding short-term efficacy on days 4-5, vaptans exhibited a significant increase in serum sodium concentration from the baseline in comparison to the control group, with a weighted mean difference of 4.77 mmol/L (95% CI, 3.57, 5.96; I2 = 34%). In terms of safety outcomes, the pooled incidence rates of overcorrection were 13.1% (95% CI 4.3, 33.6; I2 = 92%) in the vaptans group and 3.3% (95% CI 1.6, 6.6; I2 = 27%) in the control group. Despite the higher correction rate linked to vaptans, with an OR of 5.72 (95% CI 3.38, 9.70; I2 = 0%), no cases of osmotic demyelination syndrome were observed. Our meta-analysis comprehensively summarizes the efficacy and effect size of vaptans in managing SIADH. While vaptans effectively raise the serum sodium concentration compared to placebo/fluid restriction, clinicians should exercise caution regarding the potential for overcorrection.

Effect of protein supplementation on plasma sodium levels in the syndrome of inappropriate antidiuresis: a monocentric, open-label, proof-of-concept study-the TREASURE study

IMPORTANCE

The syndrome of inappropriate antidiuresis (SIAD) can be treated with oral urea; however, compliance is impaired by its poor palatability.

OBJECTIVE

To investigate whether dietary proteins could increase plasma sodium levels through urea-induced osmotic diuresis.

DESIGN

An open-label, proof-of-concept trial.

SETTING

University Hospital of Basel, Switzerland, between October 2021 and February 2023.

PARTICIPANTS

Outpatients with chronic SIAD.

INTERVENTIONS OR EXPOSURES

Ninety grams of protein daily for 7 days in the form of protein powder, followed by 30 g of oral urea daily for 7 days after a wash-out period of ≥1 week.

MAIN OUTCOMES AND MEASURES

The increase in sodium levels from baseline to the end of the 7-day protein supplementation.

RESULTS

Seventeen patients were included. After 7 days of 90 g daily protein supplementation (n = 17), plasma sodium levels increased from 131 (129-133) to 133 (132-137), that is, by a median of 3 mmol L-1 (0-5) (P = .01). Plasma urea levels increased by 3 mmol L-1 (1.7-4.9) (P < .01), and urine urea to creatinine ratio increased by 21.2 mmol mmol-1 (6.2-29.1) (P < .01). After 7 days of 30 g oral urea (n = 10), plasma sodium levels increased from 132 (130-133) to 134 (131-136), that is, by a median of 2 mmol L-1 (1-3) (P = .06). Plasma urea levels increased by 5.8 mmol L-1 (2.7-9.2) (P < .01), and urine urea to creatinine ratio increased by 31.0 mmol mmol-1 (18.7-45.1) (P < .01).

CONCLUSIONS AND RELEVANCE

Our findings suggest that protein powder increases plasma sodium levels in patients with chronic SIAD through protein-induced ureagenesis and osmotic diuresis. The effects are comparable with oral urea.

A Conspectus of Euvolemic Hyponatremia, Its Various Etiologies, and Treatment Modalities: A Comprehensive Review of the Literature

Hyponatremia is the most prevalent electrolyte imbalance encountered among hospitalized patients, athletes, the elderly, patients with chronic ailments, postoperative patients, and a few asymptomatic individuals. Clinical manifestations of hyponatremia can be diverse, with characteristic neurological symptoms. Depending on in-depth medical history, physical examination (including volume status assessment), laboratory investigation, and drug history, patients can be classified broadly as undergoing hypervolemic, euvolemic, or hypovolemic hyponatremia. However, patients with hypervolemic hyponatremia often present with distinctive signs such as edema or ascites, and the clinical presentation of hypovolemic and euvolemic hyponatremia poses significant challenges for clinicians. The convolution in clinical manifestations of patients is due to the varied etiologies of euvolemic hyponatremia, such as syndrome of inappropriate antidiuretic hormone secretion (SIADH), adrenocortical insufficiency, hypothyroidism, psychogenic polydipsia, different classes of drugs (chemotherapeutics, antipsychotics, antidepressants), endurance exercise events, and reset osmostat syndrome (ROS). The management of hyponatremia depends on the rate of hyponatremia onset, duration, severity of symptoms, levels of serum sodium, and underlying comorbidities. Over the last decade, the clinical understanding of hyponatremia has been scattered due to the introduction of innovative laboratory markers and new drugs. This article will be a conspectus of all the recent advancements in the field of diagnosis, investigations, management, and associations of hyponatremia, along with traditional clinical practices. Subsequently, a holistic overview has been laid out for the clinicians to better understand and identify knowledge deficiencies on this topic.

Use of the osmolal gap in diagnosing mixed physiology hyponatremia in a child with B-cell acute lymphoblastic leukemia

Hyponatremia is common among children undergoing treatment for hematologic malignancies and may be attributed to multiple underlying causes. In cases of hyponatremia due to mixed physiology, the osmolal gap, can identify pseudohyponatremia that may be masked by other causes.

The Efficacy of Immunotherapy in Long-Term Survival in Non-Small Cell Lung Cancer (NSCLC) Associated with the Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)

INTRODUCTION

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common cause of hyponatremia in cancer patients, occurring most frequently in patients with small cell lung cancer. However, this syndrome occurs extremely rarely in patients with non-small cell lung cancer. The results of the clinical trials have revealed that immuno-oncological therapies are effective for long periods of time, providing hope for long survival and with a good quality of life.

CASE PRESENTATION

We present the case of a female patient who was 62 years old at the time of diagnosis in 2016 who underwent surgery for a right pulmonary tumor (pulmonary adenocarcinoma) and subsequently underwent adjuvant chemotherapy. The patient had a left inoperable mediastinohilar relapse in 2018, which was treated using polychemotherapy The patient also had an occurrence of progressive metastasis and a syndrome of inappropriate antidiuretic hormone secretion (SIADH) in 2019 for which immunotherapy was initiated. The patient has continued with immunotherapy until the time this study began to be written (April 2023), the results being the remission of hyponatremia, the clinical benefits and long-term survival.

DISCUSSION

The main therapeutic option for SIADH in cancer patients is the treatment of the underlying disease, and its correction depends almost exclusively on a good response to oncological therapy. The initiation of immunotherapy at the time of severe hyponatremia occurrence led to its remission as well as the remission of the other two episodes of hyponatremia, which the patient presented throughout the evolution of the disease, demonstrating an obvious causal relationship between SIADH and the favorable response to immunotherapy.

CONCLUSIONS

Each patient must be approached individually, taking into account the various particular aspects. Immunotherapy proves to be the innovative treatment that contributes to increasing the survival of patients with metastatic non-small cell lung cancer and to increasing their quality of life.

Natural Peptide Toxins as an Option for Renewed Treatment of Type 2 Vasopressin Receptor-Related Diseases

The type 2 vasopressin receptor (V2R) is expressed in the kidneys, and it is the keystone of water homeostasis. Under the control of the antidiuretic hormone vasopressin, the V2R ensures vital functions, and any disturbance has dramatic consequences. Despite decades of research to develop drugs capable of activating or blocking V2R function to meet real medical needs, only one agonist and one antagonist are virtually used today. These two drugs cover only a small portion of patients' needs, leaving millions of patients without treatment. Natural peptide toxins known to act selectively and at low doses on their receptor target could offer new therapeutic options.

Overcorrection and undercorrection with fixed dosing of bolus hypertonic saline for symptomatic hyponatremia

OBJECTIVE

Current guidelines recommend treating symptomatic hyponatremia with rapid bolus-wise infusion of fixed volumes of hypertonic saline regardless of body weight. We hypothesize that this approach is associated with overcorrection and undercorrection in patients with low and high body weight.

DESIGN

Single-center, retrospective cohort study.

METHODS

Data were collected on patients treated with ≥1 bolus 100 or 150 mL 3% NaCl for symptomatic hyponatremia between 2017 and 2021. Outcomes were overcorrection (plasma sodium rise > 10 mmol/L/24 h, > 18 mmol/L/48 h, or relowering therapy) and undercorrection (plasma sodium rise < 5 mmol/L/24 h). Low body weight and high body weight were defined according to the lowest (≤60 kg) and highest (≥80 kg) quartiles.

RESULTS

Hypertonic saline was administered to 180 patients and caused plasma sodium to rise from 120 mmol/L to 126.4 mmol/L (24 h) and 130.4 mmol/L (48 h). Overcorrection occurred in 32 patients (18%) and was independently associated with lower body weight, weight ≤ 60 kg, lower baseline plasma sodium, volume depletion, hypokalemia, and less boluses. In patients without rapidly reversible causes of hyponatremia, overcorrection still occurred more often in patients ≤ 60 kg. Undercorrection occurred in 52 patients (29%) and was not associated with body weight or weight ≥ 80 kg but was associated with weight ≥ 100 kg and lean body weight in patients with obesity.

CONCLUSION

Our real-world data suggest that fixed dosing of bolus hypertonic saline may expose patients with low and high body weight to more overcorrection and undercorrection, respectively. Prospective studies are needed to develop and validate individualized dosing models.

Consensus document on the management of hyponatraemia of the Acqua Group of the Spanish Society of Endocrinology and Nutrition

INTRODUCTION

Hyponatremia is the most prevalent electrolyte disorder in the outpatient and inpatient settings. Despite this frequency, hyponatremia, including severe hyponatremia, is frequently underestimated and inadequately treated, thus highlighting the need to produce consensus documents and clinical practice guidelines geared towards improving the diagnostic and therapeutic approach to it in a structured fashion.

MATERIAL AND METHODS

Members of the Acqua Group of the Spanish Society of Endocrinology and Nutrition (SEEN) met using a networking methodology over a period of 20 months (between October 2019 and August 2021) with the aim of discussing and developing an updated guideline for the management of hyponatraemia. A literature search of the available scientific evidence for each section presented in this document was performed.

RESULTS

A document with 8 sections was produced, which sets out to provide updated guidance on the most clinically relevant questions in the management of hyponatraemia. The management of severe hyponatraemia is based on the i.v. administration of a 3% hypertonic solution. For the management of chronic euvolemic hyponatraemia, algorithms for the initiation of treatment with the two pharmacological therapeutic options currently available in Spain are presented: urea and tolvaptan.

CONCLUSIONS

This document sets out to simplify the approach to and the treatment of hyponatraemia, making it easier to learn and thus improve the clinical approach to hyponatremia.

Paraneoplastic Syndromes from Head to Toe: Pathophysiology, Imaging Features, and Workup

Patients often have symptoms due to the mass effect of a neoplasm on surrounding tissues or the development of distant metastases. However, some patients may present with clinical symptoms that are not attributable to direct tumor invasion. In particular, certain tumors may release substances such as hormones or cytokines or trigger an immune cross-reactivity between malignant and normal body cells, resulting in characteristic clinical features that are broadly referred to as paraneoplastic syndromes (PNSs). Recent advances in medicine have improved the understanding of the pathogenesis of PNSs and enhanced their diagnosis and treatment. It is estimated that 8% of patients with cancer develop a PNS. Diverse organ systems may be involved, most notably the neurologic, musculoskeletal, endocrinologic, dermatologic, gastrointestinal, and cardiovascular systems. Knowledge of various PNSs is necessary, as these syndromes may precede tumor development, complicate the patient's clinical presentation, indicate tumor prognosis, or be mistaken for metastatic spread. Radiologists should be familiar with the clinical presentations of common PNSs and the selection of appropriate imaging examinations. Many of these PNSs have imaging features that can assist with arriving at the correct diagnosis. Therefore, the key radiographic findings associated with these PNSs and the diagnostic pitfalls that can be encountered during imaging are important, as their detection can facilitate early identification of the underlying tumor, reveal early recurrence, and enable monitoring of the patient's response to therapy. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Hyponatremia and Cancer: From Bedside to Benchside

Hyponatremia is the most common electrolyte disorder encountered in hospitalized patients. This applies also to cancer patients. Multiple causes can lead to hyponatremia, but most frequently this electrolyte disorder is due to the syndrome of inappropriate antidiuresis. In cancer patients, this syndrome is mostly secondary to ectopic secretion of arginine vasopressin by tumoral cells. In addition, several chemotherapeutic drugs induce the release of arginine vasopressin by the hypothalamus. There is evidence that hyponatremia is associated to a more negative outcome in several pathologies, including cancer. Many studies have demonstrated that in different cancer types, both progression-free survival and overall survival are negatively affected by hyponatremia, whereas the correction of serum [Na⁺] has a positive effect on patient outcome. In vitro studies have shown that cells grown in low [Na⁺] have a greater proliferation rate and motility, due to a dysregulation in intracellular signalling pathways. Noteworthy, vasopressin receptors antagonists, which were approved more than a decade ago for the treatment of euvolemic and hypervolemic hyponatremia, have shown unexpected antiproliferative effects. Because of this property, vaptans were also approved for the treatment of polycystic kidney disease. In vitro evidence indicated that this family of drugs effectively counteracts proliferation and invasivity of cancer cells, thus possibly opening a new scenario among the pharmacological strategies to treat cancer.

Amyotrophic Lateral Sclerosis-Related Respiratory Failure and Association With Inappropriate Secretion Syndrome of the Antidiuretic Hormone

There is an unclear association between the syndrome of inappropriate antidiuretic hormone secretion (SIADH) and amyotrophic lateral sclerosis (ALS), with few reports in the literature. We report the case of an 80-year-old man admitted to our emergency room with asthenia, dysphonia, dysphagia, weight loss, and euvolemic hyponatremia, indicating a SIADH. Posteriorly, the patient also developed respiratory failure, which, in association with the previous clinical presentation, led to the diagnosis of ALS. During her permanence at the hospital, the hyponatremia improved with noninvasive positive-pressure ventilation, and the association between these two identities was made. This case also shows that patients with ALS commonly suffer from chronic respiratory failure and still have a reserved prognosis.

Treatment Effect of the SGLT2 Inhibitor Empagliflozin on Chronic Syndrome of Inappropriate Antidiuresis: Results of a Randomized, Double-Blind, Placebo-Controlled, Crossover Trial

BACKGROUND

The syndrome of inappropriate antidiuresis (SIAD) is characterized by a reduction of free water excretion with consecutive hypotonic hyponatremia and is therefore challenging to treat. The sodium-glucose cotransporter 2 (SGLT2) inhibitor empagliflozin promotes osmotic diuresis via urinary glucose excretion, likely leading to increased electrolyte free water clearance.

METHODS

In this randomized, double-blind, placebo-controlled, crossover trial, we compared 4-week treatment with empagliflozin 25 mg/d to placebo in outpatients with chronic SIAD-induced hyponatremia. At baseline and after both treatment cycles, patients underwent different assessments including neurocognitive testing (Montreal Cognitive Assessment [MoCA]). The primary end point was the difference in serum sodium levels between treatments.

RESULTS

Fourteen patients, 50% female, with a median age of 72 years (interquartile range [IQR], 65-77), completed the trial. Median serum sodium level at baseline was 131 mmol/L (IQR, 130-132). After treatment with empagliflozin, median serum sodium level rose to 134 mmol/L (IQR, 132-136), whereas no increase was seen with placebo (130 mmol/L; IQR, 128-132), corresponding to a serum sodium increase of 4.1 mmol/L (95% confidence interval [CI], 1.7 to 6.5; P =0.004). Exploratory analyses showed that treatment with empagliflozin led to improved neurocognitive function with an increase of 1.16 (95% CI, 0.05 to 2.26) in the MoCA score. Treatment was well tolerated; no serious adverse events were reported.

CONCLUSION

The SGLT2 inhibitor empagliflozin is a promising new treatment option for chronic SIAD-induced hyponatremia, possibly improving neurocognitive function. Larger studies are needed to confirm the observed treatment effects.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT03202667.

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Long-term efficacy of empagliflozin as an add-on treatment for chronic SIAD: a case report and literature review

BACKGROUND

SLGT-2 inhibitors have recently been investigated as a promising therapy for syndrome of inappropriate antidiuresis (SIAD). However, to our knowledge, no report has been published about their use for this indication in the long term.

CASE PRESENTATION

We report the case of a 68-year-old male with type 2 diabetes and chronic SIAD, in whom serum sodium levels were not adequately controlled by urea monotherapy. Other treatment options were not viable due to inefficacy or adverse effects. The initiation of empagliflozin, in addition to urea, led to the full normalization of serum sodium. Reduction and subsequent discontinuation of urea were attempted upon patient request, but this resulted in a relapse of hyponatremia. Nevertheless, stable normonatremia was again achieved and maintained for more than 6 months after re-establishing a combination therapy with empagliflozin and urea.

CONCLUSIONS

SGLT2 inhibitors might represent an effective treatment for SIAD, even in the long term. Specific clinical trials are needed to confirm this result.

Risk Factors for Anticancer Drug-Induced Hyponatremia: An Analysis Using the Japanese Adverse Drug Report (JADER) Database

Background and Objectives: Hyponatremia is among the most prevalent electrolyte abnormalities observed in patients with cancer during chemotherapy. Therefore, managing hyponatremia is crucial since it causes a severe electrolyte imbalance that can lead to significant mortality, and this study aimed to investigate the relationship between hyponatremia, anticancer drugs, and cancer types. Materials and Methods: Reported odds ratios were calculated and evaluated based on adverse event reports submitted to the Japanese Adverse Drug Event Report (JADER) database. Results: Overall, 2943 patients had hyponatremia. Notably, cisplatin, pemetrexed, and etoposide had marked hyponatremia signals. In addition, significant hyponatremia signals were detected for oesophageal, lung, and renal cancers. Conclusions: Hyponatremia has been reported in women and patients with lung cancer receiving cisplatin, with a growing trend in the number of elderly patients receiving cisplatin. Furthermore, since the onset of hyponatremia during cisplatin administration is frequently reported within 10 days, patient information should be thoroughly examined before and monitored throughout the administration, which can contribute to the early detection and prevention of hyponatremia.

Hyponatremic encephalopathy due to polyethylene glycol-based bowel preparation for colonoscopy: A case report

BACKGROUND

Adequate bowel preparation is critical for colonoscopy screening. At present, the most widely used intestinal cleaner recommended at home and abroad is Polyethylene glycol (PEG). Intestinal cleansers can cause electrolyte disturbances and hyponatremia. However, hyponatremic encephalopathy due to hyponatremia induced by PEG solution, although rare, can lead to serious irreversible sequelae and even death.

CASE SUMMARY

In this report, we discuss a case of neurological dysfunction due to hyponatremia, also known as hyponatremic encephalopathy, observed in a 63-year-old woman who underwent PEG-based bowel preparation for colonoscopy. She was eventually transferred to our intensive care unit for treatment due to her Glasgow Coma Scale score of 9/15 (Eye opening 2; Verbal response 1; Motor response 6) and abnormal laboratory tests.

CONCLUSION

Physicians should be thoroughly familiarized with the patient's history before prescribing PEG for bowel preparation, and timely identification of patients with hyponatremic encephalopathy is essential as delayed treatment is associated with poor neurological outcomes. An intravenous infusion of 3% sodium chloride is recommended at the onset of early symptoms. The goal of treatment is to adequately treat cerebral edema while avoiding serum sodium correction beyond 15 to 20 mEq/L within 48 h of treatment to prevent osmotic demyelination syndrome.

Kidney collecting duct cells make vasopressin in response to NaCl-induced hypertonicity

Vasopressin has traditionally been thought to be produced by the neurohypophyseal system and then released into the circulation where it regulates water homeostasis. The questions of whether vasopressin could be produced outside of the brain and if the kidney could be a source of vasopressin are raised by the syndrome of inappropriate antidiuretic hormone secretion (vasopressin). We found that mouse and human kidneys expressed vasopressin mRNA. Using an antibody that detects preprovasopressin, we found that immunoreactive preprovasopressin protein was found in mouse and human kidneys. Moreover, we found that murine collecting duct cells made biologically active vasopressin, which increased in response to NaCl-mediated hypertonicity, and that water restriction increased the abundance of kidney-derived vasopressin mRNA and protein expression in mouse kidneys. Thus, we provide evidence of biologically active production of kidney-derived vasopressin in kidney tubular epithelial cells.