Medication-induced SIADH: distribution and characterization according to medication class

Arginine vasopressin in mood disorders: A potential biomarker of disease pathology and a target for pharmacologic intervention

Vasopressin or arginine-vasopressin (AVP) is a neuropeptide molecule known for its antidiuretic effects and serves to regulate plasma osmolality and blood pressure. The existing literature suggests that AVP plays a multifaceted-though less well-known-role in the central nervous system (CNS), particularly in relation to the pathophysiology and treatment of mood disorders. Animal models have demonstrated that AVP is implicated in regulating social cognition, affiliative and prosocial behaviors, and aggression, often in conjunction with oxytocin. In humans, AVP is implicated in mood disorders through its effects on the hypothalamic-pituitary-adrenal (HPA) axis as well as on the serotoninergic and glutamatergic systems. Measuring plasma AVP has yielded interesting but mixed results in mood and stress-related disorders. Recent advances have led to the development of copeptin as a stable and reliable surrogate biomarker for AVP. Another interesting but relatively unexplored issue is the interaction between the osmoregulatory system and mood disorder pathophysiology, given that psychotropic medications often cause dysregulation of AVP receptor expression or signaling that can subsequently lead to clinical syndromes like syndrome of inappropriate diuresis and diabetes insipidus. Finally, pharmaceutical trials of agents that act on V1a and V1b receptor antagonists are still underway. This narrative review summarizes: (1) the neurobiology of the vasopressinergic system in the CNS; (2) the interaction between AVP and the monoaminergic and glutamatergic pathways in the pathophysiology and treatment of mood disorders; (3) the iatrogenic AVP dysregulation caused by psychotropic medications; and (4) the pharmaceutical development of AVP receptor antagonists for the treatment of mood disorders.

Postoperative Hyponatremia After Endoscopic Endonasal Resection of Pituitary Adenomas: Historical Complication Rates and Risk Factors

BACKGROUND

Hyponatremia is a common complication following endoscopic endonasal resection (EER) of pituitary adenomas. We report a single-center, multisurgeon study detailing baseline clinical data, outcomes, and factors associated with postoperative hyponatremia.

METHODS

This was a retrospective cohort study of patients undergoing EER for pituitary adenoma at Tufts Medical Center. Most procedures were performed by the senior author (C.B.H.). Cases were included if at least 1 postoperative sodium value was available and pathology confirmed pituitary adenoma. Hyponatremia was defined as a postoperative sodium level <135 mEq/L.

RESULTS

A total of 272 patients underwent 310 EER procedures that met the study inclusion criteria. The mean patient age was 53.3 years, and mean tumor size was 18.8 mm. Postoperative hyponatremia occurred in 12.6% of cases, with 3.6% developing hyponatremia prior to discharge. Lower preoperative sodium level was associated with an increased risk of developing any postoperative hyponatremia. Older age, prolactinoma pathology, and use of selective serotonin reuptake inhibitors were associated with moderate to severe hyponatremia (≤129 mEq/L), and lower preoperative sodium was associated with mild hyponatremia (130-134 mEq/L). Hyponatremia-related readmissions within 30 days occurred in 3.9% of patients. Both African-American race and postoperative hyponatremia were associated with an increased risk of 30-day readmission. The mean nadir sodium for hyponatremic patients was 129.9 mEq/L. Growth hormone-secreting pathology was associated with lower postoperative nadir sodium, whereas higher preoperative sodium was associated with higher postoperative nadir sodium.

CONCLUSIONS

Hyponatremia is a common postoperative complication of EER for pituitary lesions that can cause significant morbidity, increased readmissions, and increased healthcare costs.

[Electrolyte disorders in oncological patients]

Electrolyte disorders (ED) are common in patients with cancer and in most cases, the etiologies do not differ from the general population. They may also be induced by the cancer, its therapy or paraneoplastic syndromes. ED are associated with poor outcomes, increased morbidity and mortality in this population. Hyponatremia is the most common disorder, often multifactorial, iatrogenic or secondary to the syndrome of inappropriate antidiuretic hormone secretion, usually due to small cell lung cancer. More rarely, hyponatremia may reveal adrenal insufficiency. Hypokalemia is generally multifactorial and associated with other ED. Cisplatin and ifosfamide induce proximal tubulopathies with hypokalemia and/or hypophosphatemia. Hypomagnesemia is often iatrogenic, related to cisplatin or cetuximab, but can be prevented by supplementation. Hypercalcemia can impair life quality and be life-threatening in the most severe cases. Hypocalcemia is less common and often of iatrogenic origin. Finally, the tumor lysis syndrome is a diagnostic and therapeutic emergency that affects the prognosis of patients. Its incidence tends to increase in solid oncology, related to the improvement of therapies. Prevention and early diagnosis of ED are essential to optimize the overall management of patients with underlying cancer and cancer therapy. The aim of this review is to synthesize most frequent ED and their management.

Treatment of Anxiety Disorders in Primary Care: What Nurse Practitioners Need to Know

Anxiety disorders are the most common mental illnesses and frequently co-occur with other mental and somatic symptoms or disorders. Primary care nurse practitioners (NPs) are key in reducing the treatment gap through early identification, treatment, and/or referral to behavioral health providers. Confronting primary care NPs are problems with time constraints, multiple comorbidities, and limited mental health training, particularly in relation to the differences in pharmacokinetic and pharmacodynamic actions of first-line anxiety disorder medications across age groups. The current article provides a brief summary of evidence-based treatment focusing on pharmacotherapy for anxiety disorders in the primary care setting. [Journal of Psychosocial Nursing and Mental Health Services, 62(5), 7-10.].

A case report of severe hyponatremia secondary to Paxlovid-induced SIADH

Nirmatrelvir-ritonavir (Paxlovid) is a brand-new oral antiviral medication for treating mild to severe COVID-19. The Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for ritonavir-nirmatrelvir on December 22, 2021, to treat COVID-19. We describe a case of mild COVID-19 infection who developed severe hyponatremia following the administration of Paxlovid. Clinical and laboratory evaluations suggest SIADH, likely secondary to Paxlovid. The potential side effects of this medication still require further study.

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) Complicated by Generalized Tonic-Clonic Seizures After a Course of Antibiotics: A Case Report

Nitrofurantoin and cephalexin are commonly used antibiotics for treating urinary tract infections. Hyponatremia secondary to syndrome of inappropriate antidiuretic hormone secretion (SIADH) has been reported as a rare side effect of nitrofurantoin but has never been a reported side effect of cephalexin. We report a case of a 48-year-old female who developed severe hyponatremia complicated by generalized tonic-clonic seizures after a course of antibiotics (nitrofurantoin followed by cephalexin) used for treating a urinary tract infection. She presented to the emergency department with a one-week history of dizziness, nausea, fatigue, and listlessness. She also had a two-week history of persistent urinary frequency despite completing a course of nitrofurantoin followed by a course of cephalexin. While in the emergency department waiting room, she had two episodes of generalized tonic-clonic seizures. Immediate post-ictal blood test results revealed severe hyponatremia and lactic acidosis. Results were consistent with severe SIADH and she was subsequently managed with hypertonic saline and fluid restriction. She was discharged after 48 hours of admission when her serum sodium levels normalized. Though we believe that nitrofurantoin was the culprit drug, we still asked the patient to avoid future use of both nitrofurantoin and cephalexin. Healthcare providers need to be aware of antibiotic-induced SIADH when assessing patients with hyponatremia.

Syndrome of inappropriate secretion of antidiuretic hormone after total proctocolectomy for ulcerative colitis

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

Pathophysiology of Drug-Induced Hyponatremia

Drug-induced hyponatremia caused by renal water retention is mainly due to syndrome of inappropriate antidiuresis (SIAD). SIAD can be grouped into syndrome of inappropriate antidiuretic hormone secretion (SIADH) and nephrogenic syndrome of inappropriate antidiuresis (NSIAD). The former is characterized by uncontrolled hypersecretion of arginine vasopressin (AVP), and the latter is produced by intrarenal activation for water reabsorption and characterized by suppressed plasma AVP levels. Desmopressin is useful for the treatment of diabetes insipidus because of its selective binding to vasopressin V2 receptor (V2R), but it can induce hyponatremia when prescribed for nocturnal polyuria in older patients. Oxytocin also acts as a V2R agonist and can produce hyponatremia when used to induce labor or abortion. In current clinical practice, psychotropic agents, anticancer chemotherapeutic agents, and thiazide diuretics are the major causes of drug-induced hyponatremia. Among these, vincristine and ifosfamide were associated with sustained plasma AVP levels and are thought to cause SIADH. However, others including antipsychotics, antidepressants, anticonvulsants, cyclophosphamide, and thiazide diuretics may induce hyponatremia by intrarenal mechanisms for aquaporin-2 (AQP2) upregulation, compatible with NSIAD. In these cases, plasma AVP levels are suppressed by negative feedback. In rat inner medullary collecting duct cells, haloperidol, sertraline, carbamazepine, and cyclophosphamide upregulated V2R mRNA and increased cAMP production in the absence of vasopressin. The resultant AQP2 upregulation was blocked by a V2R antagonist tolvaptan or protein kinase A (PKA) inhibitors, suggestive of the activation of V2R-cAMP-PKA signaling. Hydrochlorothiazide can also upregulate AQP2 in the collecting duct without vasopressin, either directly or via the prostaglandin E2 pathway. In brief, nephrogenic antidiuresis, or NSIAD, is the major mechanism for drug-induced hyponatremia. The associations between pharmacogenetic variants and drug-induced hyponatremia is an area of ongoing research.

Fluid management in hospitalized pediatric patients

The proper use of intravenous fluids has likely been responsible for saving more lives than any other group of substances. Proper use includes prescribing an appropriate electrolyte and carbohydrate solution, at a calculated rate or volume, for the right child, at the right time. Forming intravenous fluid plans for hospitalized children requires an understanding of water and electrolyte physiology in healthy children and how different pathology deviates from the norm. This review highlights fluid management in several disease types, including liver disease, diabetic ketoacidosis, syndrome of inappropriate antidiuretic hormone, diabetes insipidus, kidney disease, and intestinal failure as well as in those with nonphysiologic fluid losses. For each disease, the review discusses specific considerations, evaluations, and management strategies to consider when customizing intravenous fluid plans. Ultimately, all hospitalized children should receive an individualized fluid plan with recurrent evaluations and fluid modifications to provide optimal care.

High Urinary Sodium Concentrations in Severe SIADH: Case Reports of 2 Patients and Literature Review

We present two cases of severe hyponatremia secondary to syndrome of inappropriate secretion of antidiuretic hormone (SIADH) with very high urine sodium concentrations (>130 mmol/L). The first patient had hyponatremia from traumatic brain injury (TBI) while the second case had a history of recurrent SIADH triggered by various causes including gastritis. In both cases, fluid administration and/or consumption worsened the hyponatremia. Although a low urine sodium of <30 mmol/L is highly suggestive of hypovolemic hyponatremia and good response to saline infusion, there is lack of clarity of the threshold of which high urine sodium concentration can differentiate various causes of natriuresis such as SIADH, renal or cerebral salt wasting. Apart from high urine osmolality (>500 mOsm/kg), persistence of high urine sodium concentrations may be useful to predict poor response to fluid restriction in SIADH. More studies are needed to delineate treatment pathways of patients with very high urine osmolality and urine sodium concentrations in SIADH.

Hypouricemia and Urate Transporters

Hypouricemia is recognized as a rare disorder, defined as a serum uric acid level of 2.0 mg/dL or less. Hypouricemia is divided into an overexcretion type and an underproduction type. The former typical disease is xanthinuria, and the latter is renal hypouricemia (RHUC). The frequency of nephrogenic hypouricemia due to a deficiency of URAT1 is high in Japan, accounting for most asymptomatic and persistent cases of hypouricemia. RHUC results in a high risk of exercise-induced acute kidney injury and urolithiasis. It is vital to promote research on RHUC, as this will lead not only to the elucidation of its pathophysiology but also to the development of new treatments for gout and hyperuricemia.

Management of SIADH-related hyponatremia due to psychotropic medications - An expert consensus from the Association of Medicine and Psychiatry

OBJECTIVE

Hyponatremia is the most common electrolyte imbalance encountered in clinical practice and is associated with negative healthcare outcomes and cost. SIADH is thought to account for one third of all hyponatremia cases and is typically an insidious process. Psychotropic medications are commonly implicated in the etiology of drug induced SIADH. There is limited guidance for clinicians on management of psychotropic-induced SIADH.

METHODS

After an extensive review of the existing literature, clinical-educators from the Association of Medicine and Psychiatry developed expert consensus recommendations for management of psychotropic-induced SIADH. A risk score was proposed based on risk factors for SIADH to guide clinical decision-making.

RESULTS

SSRIs, SNRIs, antipsychotics, carbamazepine, and oxcarbazepine have moderate to high level of evidence demonstrating their association with SIADH. Evaluation for an avoidance of medications that cause hyponatremia is particularly important. Substitution with medication that is less likely to cause SIADH should be considered when appropriate. We propose an algorithmic approach to monitoring hyponatremia with SIADH and corresponding treatment depending on symptom severity.

CONCLUSIONS

The proposed algorithm can help clinicians in determining whether psychotropic medication should be stopped, reduced or substituted where SIADH is suspected with recommendations for sodium (Na+) monitoring. These recommendations preserve a role for clinical judgment in the management of hyponatremia with consideration of the risks and benefits, which may be particularly relevant for complex patients that present with medical and psychiatric comorbidities. Further studies are needed to determine whether baseline and serial Na+ monitoring reduces morbidity and mortality.

Potential Use of Pharmacogenetics to Reduce Drug-Induced Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

Syndrome of inappropriate antidiuretic hormone (SIADH) is a common cause of hyponatremia, and many cases represent adverse reactions to drugs that alter ion channel conductance within the peptidergic nerve terminals of the posterior pituitary. The frequency of drug-induced SIADH increases with age; as many as 20% of patients residing in nursing homes have serum sodium levels below 135 mEq/L. Mild hyponatremia is associated with cognitive changes, gait instability, and falls. Severe hyponatremia is associated with cerebral edema, seizures, permanent disability, and/or death. Although pharmacogenetic tests are now being deployed for some drugs capable of causing SIADH (e.g., antidepressants, antipsychotics, and opioid analgesics), the implementation of these tests has been based upon the prior known association of these drugs with other serious adverse drug reactions (e.g., electrocardiographic abnormalities). Work is needed in large observational cohorts to quantify the strength of association between pharmacogene variants and drug-induced SIADH so that decision support can be developed to identify patients at high risk.

Routine postoperative fluid restriction to prevent syndrome of inappropriate antidiuretic hormone secretion after transsphenoidal resection of pituitary adenoma

OBJECTIVE

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a common problem during the postoperative course after pituitary surgery. Although treatment of this condition is well characterized, prevention strategies are less studied and reported. The authors sought to characterize outcomes and predictive factors of SIADH after implementation of routine postoperative fluid restriction for patients undergoing endoscopic transsphenoidal surgery for pituitary adenoma.

METHODS

In March 2018, routine postoperative fluid restriction to 1000 ml/day for 7 days was instituted for all patients who underwent surgery for pituitary adenoma. These patients were compared with patients who underwent surgery for pituitary adenoma between March 2016 and March 2018, prior to implementation of routine fluid restriction. Patients with preoperative history of diabetes insipidus (DI) or concern for postsurgical DI were excluded. Patients were followed by neuroendocrinologists and neurosurgeons, and sodium levels were checked between 7 and 10 days postoperatively. SIADH was defined by a serum sodium level less than 136 mmol/L, with or without symptoms within 10 days after surgery. Thirty-day readmission was recorded and reviewed to determine underlying reasons.

RESULTS

In total, 82 patients in the fluid-unrestricted cohort and 135 patients in the fluid-restricted cohort were analyzed. The patients in the fluid-restricted cohort had a significantly lower rate of postoperative SIADH than patients in the fluid-unrestricted cohort (5% vs 15%, adjusted OR [95% CI] 0.1 [0.0-0.6], p = 0.01). Higher BMI was associated with lower rate of postoperative SIADH (adjusted OR [95%] 0.9 [0.9-1.0], p = 0.03), whereas female sex was associated with higher rate of SIADH (adjusted OR [95% CI] 3.1 [1.1-9.8], p = 0.03). There was no difference in the 30-day readmission rates between patients in the fluid-unrestricted and fluid-restricted cohorts (4% vs 7%, adjusted OR [95% CI] 0.5 [0-5.1], p = 0.56). Thirty-day readmission was more likely for patients with history of hypertension (adjusted OR [95% CI] 5.7 [1.3-26.3], p = 0.02) and less likely for White patients (adjusted OR [95% CI] 0.3 [0.1-0.9], p = 0.04).

CONCLUSIONS

Routine fluid restriction reduced the rate of SIADH in patients who underwent surgery for pituitary adenoma but was not associated with reduction in 30-day readmission rate.

Hyponatremia Following Antipsychotic Treatment: In Silico Pharmacodynamics Analysis of Spontaneous Reports From the US Food and Drug Administration Adverse Event Reporting System Database and an Updated Systematic Review

BACKGROUND

Hyponatremia associated with antipsychotic drugs is a rare but potentially life-threatening adverse drug reaction; the underlying pharmacological mechanism has not yet been explained.

METHODS

We investigated the relationship between pharmacological targets of antipsychotic drugs and the occurrence of hyponatremia by conducting a nested case-control study using the Food and Drug Administration Adverse Event Reporting System database. Multiple logistic regression was used to determine the associations between antipsychotics receptor occupancy and hyponatremia. We also performed a systematic review of clinical studies on this association.

RESULTS

Of 139 816 reports involving at least 1 antipsychotic, 1.1% reported hyponatremia. Olanzapine was the most frequently suspected drug (27%). A significant positive association was found between dopamine D3, D4, and hyponatremia, while adrenergic α 1, serotonin 5-HT1A, and 5-HT2A receptor occupancies were negatively associated. A multivariable stepwise regression model showed that dopamine D3 (adj. odds ratio = 1.21; 95% CI = 1.09-1.34; P < .05) predicted the risk for hyponatremia (P < .05), while serotonin 5-HT2A occupancy (Adj. odds ratio = 0.78; 95% CI = 0.68-0.90; P < .01) exhibited a protective effect against hyponatremia. Among the 11 studies included in the systematic review, incidence rates of hyponatremia diverged between 0.003% and 86%, whereas the odds of developing hyponatremia from effect studies ranged between 0.83 and 3.47.

CONCLUSIONS

Antipsychotic drugs having a combined modest occupancy for D3 and 5-HT2A receptors and higher levels of D3 receptor occupancy correspond to different degrees of risk for hyponatremia. Based on the few, relatively large-scale available studies, atypical antipsychotics have a more attenuated risk profile for hyponatremia.

Psychotropic drug-induced hyponatremia: results from a drug surveillance program-an update

Hyponatremia (HN) is the most common electrolyte imbalance (defined as a serum sodium concentration Na(S) of  < 130 mmol/l) and often induced by drugs including psychotropic drugs. AMSP (Arzneimittelsicherheit in der Psychiatrie) is a multicenter drug surveillance program that assesses severe or unusual adverse drug reactions (ADRs) occurring during treatment with psychotropic drugs. This study presents data from 462,661 psychiatric inpatients treated in participating hospitals between 1993 and 2016 and serves as an update of a previous contribution by Letmaier et al. (JAMA 15(6):739–748, 2012). A total of 210 cases of HN were observed affecting 0.05% of patients. 57.1% of cases presented symptomatically; 19.0% presented with severe symptoms (e.g., seizures, vomiting). HN occurred after a median of 7 days following the first dose or dose increase. Incidence of HN was highest among the two antiepileptic drugs oxcarbazepine (1.661% of patients treated) and carbamazepine (0.169%), followed by selective serotonin-norepinephrine reuptake inhibitors (SSNRIs, 0.088%) and selective serotonin reuptake inhibitors (0.071%). Antipsychotic drugs, tricyclic antidepressants, and mirtazapine exhibited a significantly lower incidence of HN. The risk of HN was 16–42 times higher among patients concomitantly treated with other potentially HN-inducing drugs such as diuretic drugs, angiotensin-converting-enzyme inhibitors, angiotensin II receptor blockers, and proton pump inhibitors. Female SSNRI-users aged  ≥ 65 years concomitantly using other HN-inducing drugs were the population subgroup with the highest risk of developing HN. The identification of high-risk drug combinations and vulnerable patient subgroups represents a significant step in the improvement of drug safety and facilitates the implementation of precautionary measures.

Awareness of the use of hyponatraemia-inducing medications in older adults with hyponatraemia: a study of their prevalent use and association with recurrent symptomatic or severe hyponatraemia

BACKGROUND

Cautious use or avoidance of hyponatraemia-inducing medications (HIMs) is recommended in older patients with hyponatraemia.

OBJECTIVE

To evaluate the use of HIMs after treatment for symptomatic or severe hyponatraemia and to investigate the impact of HIMs on the recurrence of symptomatic or severe hyponatraemia in older patients.

DESIGN AND SETTINGS

A cross-sectional and nested case-control study using data obtained from national insurance claims databases.

METHODS

The rate of prescribing HIMs during the 3 months before and after the established index date was analysed in a cross-sectional analysis. Multivariable logistic regression was performed to investigate the association between HIM use and recurrence of symptomatic or severe hyponatraemia after adjusting for covariates in a case-control study.

RESULTS

The cross-sectional study included 1,072 patients treated for symptomatic or severe hyponatraemia. The proportion of patients prescribed any HIMs after hyponatraemia treatment decreased from 76.9 to 70.1%. The prescription rates significantly decreased for thiazide diuretics (from 41.9 to 20.8%) and desmopressin (from 8.6 to 4.0%), but the proportion of patients prescribed antipsychotics increased from 9.2 to 17.1%. Of 32,717 patients diagnosed with hyponatraemia, 913 (2.8%) showed recurrent hyponatraemia. After adjusting for comorbid conditions, the use of any HIMs including proton pump inhibitors [adjusted odds ratio (aOR) 1.34, 95% confidence interval (CI) 1.15-1.57] and two or more HIMs (aOR 1.48, 95% CI 1.22-1.78) especially in combination with thiazide diuretics increased the likelihood of severe hyponatraemia recurrence.

CONCLUSIONS

Prevalent use of HIMs after treatment for symptomatic or severe hyponatraemia and multiple HIM use increase the risk of recurrent hyponatraemia in geriatric patients.

A case of tripterygium glycosides-associated AGEP-like drug reaction combined with bullous pemphigoid

Acute generalized exanthematous pustulosis (AGEP) is a severe cutaneous drug reaction. Bullous pemphigoid (BP) is an acquired autoimmune disease that might be associated with drugs. There is currently no report of tripterygium glycosides (TG)-induced AGEP-like lesions combined with BP. A 66-year-old male with a 20-year history of psoriasis was prescribed oral TG at 1 mg/kg, three times a day, due to aggravated psoriasis. Seven days later, erythemas, and blisters appeared. After another 3 days, there were two types of blisters: (1) numerous small tension blisters with a lot of neutrophils on the top similar to AGEP combined with BP; (2) a BP. After intravenous injection of methylprednisolone and gamma globulin, the lesions were controlled. This patient developed two types of lesions, including one similar to AGEP combined BP (AGEP-like) and a BP. It is a rare drug reaction induced by TG.

Vasopressin-Dependent Disorders: What Is New in Children?

Arginine vasopressin (AVP)-mediated osmoregulatory disorders, such as diabetes insipidus (DI) and syndrome of inappropriate secretion of antidiuretic hormone (SIADH) are common in the differential diagnosis for children with hypo- and hypernatremia and require timely recognition and treatment. DI is caused by a failure to concentrate urine secondary to impaired production of or response to AVP, resulting in hypernatremia. Newer methods of diagnosing DI include measuring copeptin levels; copeptin is AVP's chaperone protein and serves as a surrogate biomarker of AVP secretion. Intraoperative copeptin levels may also help predict the risk for developing DI after neurosurgical procedures. Copeptin levels hold diagnostic promise in other pediatric conditions, too. Recently, expanded genotype and phenotype correlations in inherited DI disorders have been described and may better predict the clinical course in affected children and infants. Similarly, newer formulations of synthetic AVP may improve pediatric DI treatment. In contrast to DI, SIADH, characterized by inappropriate AVP secretion, commonly leads to severe hyponatremia. Contemporary methods aid clinicians in distinguishing SIADH from other hyponatremic conditions, particularly cerebral salt wasting. Further research on the efficacy of therapies for pediatric SIADH is needed, although some adult treatments hold promise for pediatrics. Lastly, expansion of home point-of-care sodium testing may transform management of SIADH and DI in children. In this article, we review recent developments in the understanding of pathophysiology, diagnostic workup, and treatment of better outcomes and quality of life for children with these challenging disorders.

[SYNDROME OF INAPPROPRIATE ANTIDIURETIC HORMONE SECRETION AS A SIDE EFFECT OF CHEMOTHERAPY FOR URACHAL CARCINOMA: A CASE REPORT]

A 54-year-old woman was admitted to our hospital complaining of gross hematuria and difficulty urinating. Cystoscopy revealed a tumor 4 cm in size with calcification on top of the bladder. After diagnosis of urachal carcinoma by transurethral resection of the bladder, partial cystectomy with en bloc resection of the median umbilical ligament and pelvic lymphadenectomy was performed. Pathological diagnosis confirmed urachal carcinoma, pT3b, ly1, v0, pN1, RM0. TS-1 and cisplatin chemotherapy (TS-1 at 100 mg/day on days 1-21, CDDP at 60 mg/m² on day 8) was administered. On day 13, the patient was admitted because of consciousness disorder (Glasgow Coma Scale E2V1M4). Hyponatremia (Na 109 mEq/l) and renal excretion of sodium were present and the patient was diagnosed with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) induced by chemotherapy. Serum sodium level and her consciousness level gradually improved after administration of 3% saline. SIADH caused by chemotherapy containing cisplatin is a relatively rare, but potentially serious adverse effect that requires close attention.

Copeptin, a surrogate marker of arginine8 vasopressin, has no ability to modulate human and mouse gastric motility

Copeptin, a glycosylated peptide fragment derived from the C-terminal region of the precursor of arginine⁸ vasopressin (AVP), is co-secreted with AVP in equimolar amounts. Elevated plasma AVP modulates gastric motility so we investigated whether copeptin had a similar effect. Copeptin (10^-9-10^-7M), and AVP (10^-12-10^-5M), were evaluated for their ability to modulate spontaneous and electrically-evoked (EFS) contractions of human proximal and distal gastric circular muscle in vitro. Similar experiments were performed on the mouse stomach and we re-examined the published effect of copeptin on the mouse aorta. In the presence of tetrodotoxin (10^-6M), atropine (10^-6M) and L-NAME (3 × 10^-4M), human proximal and distal stomach muscle contracted spontaneously and rhythmically as did mouse distal stomach. Copeptin (10^-9-10^-7M), had no effect on baseline muscle tone or myogenic spontaneous contractions of either human or mouse stomach. However, AVP concentration-dependently increased tone, amplitude and frequency of contractions in both regions of human stomach with similar potency (pEC₅₀ 9.0-9.5; n = 4) and threshold concentration (10^-11-10^-10M). AVP was similarly active in the mouse stomach. EFS-evoked cholinergic contractions (human and mouse) were unaffected by both peptides EFS-evoked relaxations of mouse stomach were unaffected by copeptin. In sub-maximally contracted mouse aorta the elevated tone was unaffected by copeptin (10^-7M) (cf. previously published study) but was reduced by carbachol (10^-6M) and sodium nitroprusside (10^-3M). We conclude that in contrast to AVP, copeptin over a concentration range reported in the plasma has no direct ability to modulate the motility of the human and mouse stomach.

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.

Pharmacokinetic Monitoring of Levetiracetam in Portuguese Refractory Epileptic Patients: Effect of Gender, Weight and Concomitant Therapy

Levetiracetam is a second-generation antiepileptic drug, widely used in the treatment of focal and generalized epilepsy due to its pharmacokinetic and safety profiles. Its pharmacokinetic monitoring is ascribed as useful to personalize its dosing regimen. The aim of the present study was to describe, for the first time, the pharmacokinetics of levetiracetam in Portuguese refractory epileptic patients. Therefore, a retrospective study was carried out on 65 Portuguese refractory epileptic patients (pharmacokinetic study: 48; validation study: 17) admitted to the Refractory Epilepsy Centre of the Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal. The pharmacokinetic parameters of levetiracetam were estimated by applying a one-compartment model with first-order absorption and elimination analysis. Male patients showed higher distribution volume (Vd/F) and oral clearance (CL/F) than female patients (median Vd/F: 52.40 L in males and 38.60 L in females, p = 0.011; median CL/F: 4.71 L/h in males and 3.91 L/h in females, p = 0.028). Higher values of Vd/F (p = 0.026) and CL/F (p = 0.003) were also found in overweight patients relative to normal weight and obese patients. Carbamazepine was the co-administered antiepileptic drug that mostly affected the pharmacokinetics of levetiracetam, increasing both Vd/F (61.30 L with carbamazepine and 39.10 L without carbamazepine, p = 0.007) and CL/F (6.71 L/h with carbamazepine and 3.91 L/h without carbamazepine, p < 0.001). The pharmacokinetics of levetiracetam was affected by gender, body mass index, and co-administration of carbamazepine. This study highlights the impact of several factors on the CL/ and Vd/F of levetiracetam when administered to refractory epileptic patients. The importance of its pharmacokinetic monitoring in clinical pharmacy stands out, thereby enabling the optimization of antiepileptic drug therapy.

Increasing prevalence of anticholinergic medication use in older people in England over 20 years: cognitive function and ageing study I and II

BACKGROUND

Anticholinergic medication use is linked with increased cognitive decline, dementia, falls and mortality, and their use should be limited in older people. Here we estimate the prevalence of anticholinergic use in England's older population in 1991 and 2011, and describe changes in use by participant's age, sex, cognition and disability.

METHODS

We compared data from participants aged 65+ years from the Cognitive Function and Ageing Studies (CFAS I and II), collected during 1990-1993 (N = 7635) and 2008-2011 (N = 7762). We estimated the prevalence of potent anticholinergic use (Anticholinergic Cognitive Burden [ACB] score = 3) and average anticholinergic burden (sum of ACB scores), using inverse probability weights standardised to the 2011 UK population. These were stratified by age, sex, Mini-Mental State Examination score, and activities of daily living (ADL) or instrumental ADL (IADL) disability.

RESULTS

Prevalence of potent anticholinergic use increased from 5.7% (95% Confidence Interval [CI] 5.2-6.3%) of the older population in 1990-93 to 9.9% (9.3-10.7%) in 2008-11, adjusted odds ratio of 1.90 (95% CI 1.67-2.16). People with clinically significant cognitive impairment (MMSE [Mini Mental State Examination] 21 or less) were the heaviest users of potent anticholinergics in CFAS II (16.5% [95% CI 12.0-22.3%]). Large increases in the prevalence of the use medication with 'any' anticholinergic activity were seen in older people with clinically significant cognitive impairment (53.3% in CFAS I to 71.5% in CFAS II).

CONCLUSIONS

Use of potent anticholinergic medications nearly doubled in England's older population over 20 years with some of the greatest increases amongst those particularly vulnerable to anticholinergic side-effects.

Mild to moderate hyponatremia at discharge is associated with increased risk of recurrence in patients with community-acquired pneumonia

BACKGROUND

Hyponatremia is the most common electrolyte disorder in hospitalized patients with pneumonia. Different studies have shown an association of hyponatremia on admission and worse patient's outcome. Yet, the impact of hyponatremia at discharge or of hyponatremia correction on patient's prognosis is unknown.

METHODS

This is a preplanned secondary data analysis from a double-blind, randomized, placebo-controlled trial of hospitalized patients with community-acquired pneumonia and prednisone treatment. The primary outcome was the impact of hyponatremia on admission and at discharge on patient relevant outcomes (i.e. mortality, rehospitalization and recurrence rate) within 180 days.

RESULTS

Of the 708 included patients, 185 (26.1%) were hyponatremic on admission. Of these, 28 (15.1%) were still hyponatremic at discharge. 34 (4.8%) patients developed hyponatremia during hospitalization despite being normonatremic on admission. Patients with hyponatremia at discharge had a higher rate of pneumonia recurrence as compared to normonatremic patients (OR 2.68; 95%-CI 1.09-6.95; p = 0.037). Among patients with hyponatremia at discharge, patients who were already hyponatremic on admission showed the strongest association with increased recurrence rate (OR 4.01; 95%-CI 1.08-12.64; p = 0.022). In contrast, recurrence rate was not affected in patients who were hyponatremic on admission but had normalized serum sodium levels at discharge (p = 0.73).

CONCLUSION

Mild to moderate hyponatremia at discharge is associated with an increased risk of recurrence in hospitalized patients with pneumonia. This association is particularly strong for patients who are hyponatremic both on admission and at discharge, emphasizing the importance of hyponatremia correction during hospitalization.

Posterior Reversible Encephalopathy Syndrome in Clinical Toxicology: A Systematic Review of Published Case Reports

Background: Posterior reversible encephalopathy syndrome (PRES) is a rare clinical and radiological entity characterized by a typical brain edema. Although several case reports have described PRES in a context of poisoning, to our knowledge, a comprehensive assessment has not been performed. The aim of this systematic review was to raise awareness on poisoning-specific PRES features and to encourage consistent and detailed reporting of substance abuse–and drug overdose–associated PRES.

Methods: Medline/PubMed, Web of Science, and PsycINFO were screened through May 31, 2019, to systematically identify case reports and case series describing PRES associated with poisoning (i.e., alcohol, drugs, illicit drugs, natural toxins, chemical substances) in accidental context, intentional overdose, and substance abuse. The methodological quality of eligible case reports/series was assessed. Patients and exposure characteristics were recorded; relevant toxicological, radiological, and clinical data were extracted.

Results: Forty-one case reports and one case series reporting 42 unique cases were included. The median time to PRES onset from the start of exposure was 3 days (IQR 2–10). Acute high blood pressure, visual disturbance, and seizure were reported in 70, 55, and 50% of patients, respectively. The initial clinical presentation was alertness disorders in 64% of patients. Nine patients (21%) required mechanical ventilation. One-third of patients had at least one risk factor for PRES such as chronic hypertension (17%) or acute/chronic kidney failure (24%). The main imaging pattern (67%) was the combination of classical parieto-occipital edema with another anatomical region (e.g., frontal, basal ganglia, posterior fossa involvement). Vasogenic edema was found in 86% of patients. Intracranial hemorrhage occurred in 14% of patients. Both brain infarction and reversible cerebral vasoconstriction syndrome were diagnosed in 5% of patients. Three patients (12%, 3/25) had non-reversible lesions on follow-up magnetic resonance imaging. The median time required to hospital discharge was 14 days (IQR 7–18). Mortality and neurological recurrence rate were null.

Conclusions: Comorbidities such as chronic hypertension and kidney failure were less frequent than in patients with other PRES etiologies. Imaging analysis did not highlight a specific pattern for poisoning-induced PRES. Although less described, PRES in the context of poisoning, which shares most of the clinical and radiological characteristics of other etiologies, is not to be ignored.

Inverse association between glucose-lowering medications and severe hyponatremia: a Swedish population-based case-control study

CONTEXT

Glucose-lowering medications have occasionally been reported to cause hyponatremia, but the evidence is scarce.

OBJECTIVES

To explore the association between glucose-lowering medications and severe hyponatremia.

DESIGN, SETTING, AND PARTICIPANTS

Subjects hospitalized with a principal diagnosis of hyponatremia (n = 14,359) were compared with matched controls (n = 57,383). Data were derived by linkage of national population-based registers. Multivariable logistic regression adjusting for co-medication, diseases, previous hospitalizations, and socioeconomic factors was used to explore the association between hospitalization for hyponatremia and the use of different glucose-lowering medications. Furthermore, newly initiated (≤90 days) and ongoing use was investigated separately.

MAIN OUTCOME MEASURES

Hospitalization due to hyponatremia.

RESULTS

The unadjusted ORs (95% CI) for hospitalization due to hyponatremia were 1.41 (1.29-1.54) for insulins, 1.38 (1.27-1.50) for metformin, and 1.22 (1.07-1.38) for sulfonylureas. However, after adjustment for confounding factors the association was consistently reversed. Thus, for any glucose-lowering medication the adjusted OR was 0.63 (0.58-0.68). For insulins, metformin and sulfonylureas, adjusted ORs (95% CI) were 0.58 (0.52-0.65), 0.81 (0.72-0.90) and 0.81 (0.69-0.94), respectively. Odds ratios for newly initated medications were overall higher while those for ongoing treatment were further decreased. Thus, adjusted ORs (95% CI) for ongoing treatment with insulins, metformin, and sulfonylureas were 0.54 (0.48-0.61), 0.82 (0.73-0.91) and 0.78 (0.66-0.92).

CONCLUSIONS

Glucose-lowering medications did not increase the risk for hospitalization due to severe hyponatremia. In fact, the association was inverse across all investigated drugs. The association may be mediated by pharmacologic mechanisms, but the uniform effects across drug-classes suggest properties of the diabetic disease are of importance.

Impending Low Intake Dehydration at Admission to A Geriatric Ward- Prevalence and Correlates in a Cross-Sectional Study

Dehydration risk increases with frailty and functional dependency, but a limited number of studies have evaluated this association in hospitalized geriatric patients. This cross-sectional study aimed to assess the prevalence and determinants of dehydration in patients admitted to the geriatric ward. Dehydration was diagnosed when calculated osmolarity was above 295 mMol/L. Logistic regression analyses (direct and stepwise backward) were used to assess determinants of impending dehydration. 358 of 416 hospitalized patients (86.1%) were included: 274 (76.5%) women, and 309 (86.4%) 75+ year-old. Dehydration was diagnosed in 209 (58.4%) cases. Significantly higher odds for impending dehydration were observed only for chronic kidney disease with trends for diabetes and procognitive medication when controlling for several health, biochemical, and nutritional parameters and medications. After adjusting for “dementia” the negative effect of “taking procognitive medications” became a significant one. Chronic kidney disease, diabetes, taking procognitive medications and hypertension were the main variables for the outcome prediction according to the stepwise backward regression analysis. This may indicate an additional benefit of reducing the risk of dehydration when using procognitive drugs in older patients with dementia.

Recurrent Severe Hyponatremia in a Patient with Sjögren's Syndrome

Sjögren's syndrome (SS) is an autoimmune disease that presents with exocrine gland dysfunction. Renal involvement is common in SS and often results in tubulointerstitial nephritis, renal tubular acidosis, and Fanconi's syndrome. Electrolyte imbalances are commonly the first symptom of renal involvement of SS. The most common feature of dysnatremia in SS is hypernatremia with diabetes insipidus. However, cases of hyponatremia with syndrome of inappropriate antidiuretic hormone secretion (SIADH) are rarely reported in patients with SS. Herein, we report a case of recurrent severe SIADH in a patient with SS.

Hyponatremia in Heart Failure: Pathogenesis and Management

Hyponatremia is a very common electrolyte abnormality, associated with poor short- and long-term outcomes in patients with heart failure (HF). Two opposite processes can result in hyponatremia in this setting: Volume overload with dilutional hypervolemic hyponatremia from congestion, and hypovolemic hyponatremia from excessive use of natriuretics. These two conditions require different therapeutic approaches. While sodium in the form of normal saline can be lifesaving in the second case, the same treatment would exacerbate hyponatremia in the first case. Hypervolemic hyponatremia in HF patients is multifactorial and occurs mainly due to the persistent release of arginine vasopressin (AVP) in the setting of ineffective renal perfusion secondary to low cardiac output. Fluid restriction and loop diuretics remain mainstay treatments for hypervolemic/dilutional hyponatremia in patients with HF. In recent years, a few strategies, such as AVP antagonists (Tolvaptan, Conivaptan, and Lixivaptan), and hypertonic saline in addition to loop diuretics, have been proposed as potentially promising treatment options for this condition. This review aimed to summarize the current literature on pathogenesis and management of hyponatremia in patients with HF.

Syndrome of inappropriate antidiuretic hormone secretion as a side effect of chemotherapy for testicular cancer: A case report

INTRODUCTION

Inappropriate antidiuretic hormone secretion syndrome can be a serious adverse event of cisplatin-based chemotherapy. Cisplatin had to be changed to other drugs or chemotherapy completely discontinued in earlier reported cases.

CASE PRESENTATION

Three cycles of bleomycin, etoposide, and cisplatin chemotherapy were planned for a 40-year-old man with a diagnosis of lymph node recurrence of testicular cancer. On day 9, he suffered from vomiting and mental disturbance. Severe hyponatremia (110 mEq/L) with low plasma osmolality led to a diagnosis of a syndrome of inappropriate antidiuretic hormone secretion, and infusions of hypertonic saline and salt intake were prescribed. Second and third courses of bleomycin, etoposide, and cisplatin chemotherapy could then be given with careful electrolyte management.

CONCLUSION

Continuation of cisplatin administration with precise electrolyte adjustment can be a treatment option in regimens where cisplatin is essential for achieving optimal antitumor efficacy.

Amiodarone-Induced Syndrome of Inappropriate Antidiuretic Hormone: A Case Report and Review of the Literature

Amiodarone (Cordarone^®, Pfizer Inc) is an antiarrhythmic medication with a well-known toxicity profile, including rare cases of hyponatremia as a result of syndrome of inappropriate antidiuretic hormone (SIADH). We report on such a case in which a patient was found to be hyponatremic after evaluation. An 88-year-old male who presented to the emergency department was found to be hyponatremic secondary to amiodarone-induced SIADH following a fall, with possible seizure and traumatic brain injury. He had a history of hypertension, paroxysmal atrial fibrillation, emphysema, myocardial infarction, benign prostatic hyperplasia, chronic kidney disease, Meniere's disease, anemia, and gastroesophageal reflux. Upon admission, his urine sodium level was elevated, and his serum sodium, urine osmolality, and anion gap were below normal. In the setting of hyponatremia, the patient's amiodarone was held: he had been taking amiodarone 200 mg once daily for nine months prior to admission. He was treated with intravenous (IV) normal saline over four days. He was fluid-restricted and his sodium levels were closely monitored every two hours. Within 19 hours, his serum sodium levels had improved. Amiodarone was restarted approximately three days later. Upon follow-up after discharge, the patient remained on amiodarone for the next two months. His serum sodium level ranged from 126 mEq/L to 131 mEq/L over a two-week period. He was supplemented with sodium chloride tablets and has been otherwise stable. Amiodarone may cause acute or chronic SIADH, with a wide range of symptoms. Seizures have not been reported in the literature but our patient had a witnessed seizure, although his electroencephalogram (EEG) was negative. Syndrome of inappropriate antidiuretic hormone can occur with any formulation of amiodarone in a dose-dependent fashion. Our patient's sodium levels stabilized within two weeks after amiodarone was resumed. The mechanism of amiodarone-induced SIADH remains unclear.

Syndrome of Inappropriate Antidiuresis

The syndrome of inappropriate antidiuresis (SIAD) is a common cause of hyponatremia in hospitalized children. SIAD refers to euvolemic hyponatremia due to nonphysiologic stimuli for arginine vasopressin production in the absence of renal or endocrine dysfunction. SIAD can be broadly classified as a result of tumors, pulmonary or central nervous system disorders, medications, or other causes such as infection, inflammation, and the postoperative state. The presence of hypouricemia with an elevated fractional excretion of urate can aid in the diagnosis. Treatment options include fluid restriction, intravenous saline solutions, oral sodium supplements, loop diuretics, oral urea, and vasopressin receptor antagonists (vaptans).

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.

Endocrinopathy-induced euvolemic hyponatremia

Euvolemic hyponatremia results from either the syndrome of inappropriate antidiuretic hormone secretion (SIADH), hypothyroidism, or adrenal insufficiency. Furthermore, the criteria for diagnosis of SIADH entail the exclusion of hypothyroidism and hypoadrenalism. We aim to assess the yield of euvolemic hyponatremia workup focusing on underlying endocrinopathies in a real-world setting. A single-center retrospective study includes all patients diagnosed with euvolemic hyponatremia in a tertiary hospital between 1.1.2007 and 1.1.2013. Demographic, clinical, and laboratory data were collected from medical charts. Euvolemic hyponatremia was detected in 564 patients. Thyroid function was tested in 69% (391/564) and adrenal function was assessed in 29% (164/564) of cases. Endocrinopathy-induced euvolemic hyponatremia was diagnosed in nine (1.6%) patients: three patients were diagnosed with hypothyroidism-induced hyponatremia, three with adrenal insufficiency as an underlying cause, and three with central hypothyroidism and central hypoadrenalism. All nine had medical history and symptoms suggestive of endocrine deficiencies other than the hyponatremia, which resolved within 1-3 days after administration of hormone replacement therapy. Yield of performed workup for hypothyroidism and hypoadrenalism in euvolemic hyponatremia was low. However, in this real-world study, only a limited number of patients underwent a full ascertainment of hypoadrenalism and hypothyroidism, which was diagnosed only in patients with additional findings supportive of these endocrinopathies; a higher rate of undiagnosed endocrinopathies cannot be ruled out. As both hypoadrenalism and hypothyroidism are easily treatable, potentially life-threatening conditions, there are insufficient data to change current recommendation for their universal evaluation in patients with euvolemic hyponatremia.

Medication-induced SIADH: distribution and characterization according to medication class

AIMS

The aims of the current study were to determine the distribution of aetiologies for the drug-induced syndrome of inappropriate antidiuretic hormone secretion (SIADH) in hospitalized patients, and to characterize them according to the different drug groups.

METHODS

A single-centre retrospective study was carried out, including all patients diagnosed with SIADH in a large community hospital and tertiary centre between 1 January 2007 and 1 January 2013 who were treated with drugs known to be associated with SIADH. Two physicians reviewed every patient's medical file for predetermined relevant clinical data.

RESULTS

The study cohort included 198 patients who had SIADH and received drugs associated with SIADH. Most patients [146 (73.7%)] were diagnosed with drug-associated SIADH, while 52 (26.3%) were diagnosed with SIADH due to other aetiologies. The Naranjo algorithm differentiated well between the two groups (P < 0.001). Five drug classes (antidepressants, anticonvulsants, antipsychotic agents, cytotoxic agents and pain medications) were implicated in 82.3% of patients diagnosed with drug-associated SIADH. Specific serotonin reuptake inhibitors and carbamazepine were commonly implicated. There were no clinically significant differences in the characteristics or severity of SIADH according to drug class.

CONCLUSIONS

The clinical characteristics of SIADH caused by different drugs are comparable. Patients with SIADH treated with drugs from five common medication classes will probably be diagnosed with drug-induced SIADH. Physicians should be aware of the significance of these medication classes as SIADH aetiologies.

Turning down the volume: Astrocyte volume change in the generation and termination of epileptic seizures

Approximately 1% of the global population suffers from epilepsy, a class of disorders characterized by recurrent and unpredictable seizures. Of these cases roughly one-third are refractory to current antiepileptic drugs, which typically target neuronal excitability directly. The events leading to seizure generation and epileptogenesis remain largely unknown, hindering development of new treatments. Some recent experimental models of epilepsy have provided compelling evidence that glial cells, especially astrocytes, could be central to seizure development. One of the proposed mechanisms for astrocyte involvement in seizures is astrocyte swelling, which may promote pathological neuronal firing and synchrony through reduction of the extracellular space and elevated glutamate concentrations. In this review, we discuss the common conditions under which astrocytes swell, the resultant effects on neural excitability, and how seizure development may ultimately be influenced by these effects.

Clinical aspects of changes in water and sodium homeostasis in the elderly

The population of elderly individuals is increasing worldwide. With aging, various hormonal and kidney changes occur, both affecting water homeostasis. Aging is a risk factor for chronic kidney disease (CKD) and many features of CKD are reproduced in the aging kidney. Dehydration and hyperosmolarity can be triggered by diminished thirst perception in this population. Elderly with dementia are especially susceptible to abnormalities of their electrolyte and body water homeostasis and should be (re-)assessed for polypharmacy. Hypo- and hypernatremia can be life threatening and should be diagnosed and treated promptly, following current practice guidelines. In severe cases of acute symptomatic hyponatremia, a rapid bolus of 100 to 150 ml of intravenous 3% hypertonic saline is appropriate to avert catastrophic outcomes; for asymptomatic hyponatremia, a very gradual correction is preferred. In summary, the body sodium (Na+) balance is regulated by a complex interplay of environmental and individual factors. In this review, we attempt to provide an overview on this topic, including dehydration, hyponatremia, hypernatremia, age-related kidney changes, water and sodium balance, and age-related changes in the vasopressin and renin-angiotensin-aldosterone system.