Symptomatic hyponatraemia due to inappropriate antidiuretic hormone secretion following minor surgery

A rare case of the syndrome of inappropriate antidiuretic hormone secretion occurring after minor surgery is presented. A ten-year-old, previously healthy boy underwent general anaesthesia for detorsion and right orchiopexy. Throughout the operations, which lasted for one hour, he received 120 ml Ringer's lactate solution. The immediate postoperative period was uneventful. Twenty-two hours postoperatively he was found unconscious with generalized tonic-clonic seizures. Simultaneously obtained serum sodium concentration (121 mEq.L-1) serum osmolarity (265 mEq.L-1), urine sodium concentration (87 mEq.L-1) and urine osmolarity (525 mEq.L-1) suggested inappropriate antidiuretic hormone secretion which was confirmed by an elevated serum arginine-vasopressin (AVP) level of 14.5 pcg.ml-1 (normal 1-5 pcg.ml-1) measured by radioimmune assay. He was treated with a single iv dose of 30 mg furosemide and fluid restriction, which produced a gradual increase of his serum sodium concentration to normal within two days. He was well during the remainder of his hospitalization.     

A systematic review and meta-analysis of thiazide-induced hyponatraemia: time to reconsider electrolyte monitoring regimens after thiazide initiation?

AIMS

Hyponatraemia is one of the major adverse effects of thiazide and thiazide-like diuretics and the leading cause of drug-induced hyponatraemia requiring hospital admission. We sought to review and analyze all published cases of this important condition.

METHODS

Ovid Medline, Embase, Web of Science and PubMed electronic databases were searched to identify all relevant articles published before October 2013. A proportions meta-analysis was undertaken.

RESULTS

One hundred and two articles were identified of which 49 were single patient case reports. Meta-analysis showed that mean age was 75 (95% CI 73, 77) years, 79% were women (95% CI 74, 82) and mean body mass index was 25 (95% CI 20, 30) kg m⁻². Presentation with thiazide-induced hyponatraemia occurred a mean of 19 (95% CI 8, 30) days after starting treatment, with mean trough serum sodium concentration of 116 (95% CI 113, 120) mm and serum potassium of 3.3 (95% CI 3.0, 3.5) mm. Mean urinary sodium concentration was 64 mm (95% CI 47, 81). The most frequently reported drugs were hydrochlorothiazide, indapamide and bendroflumethiazide.

CONCLUSIONS

Patients with thiazide-induced hyponatraemia were characterized by advanced age, female gender, inappropriate saliuresis and mild hypokalaemia. Low BMI was not found to be a significant risk factor, despite previous suggestions. The time from thiazide initiation to presentation with hyponatraemia suggests that the recommended practice of performing a single investigation of serum biochemistry 7–14 days after thiazide initiation may be insufficient or suboptimal. Further larger and more systematic studies of thiazide-induced hyponatraemia are required.     

Hyponatraemia in heart failure

Hyponatraemia is common in heart failure (HF). It is estimated that over 20% of patients admitted to hospital with HF have hyponatraemia. It has also been repeatedly shown to be a surrogate marker of increased morbidity and mortality in this specific population. This review focuses on the pathophysiology of hyponatraemia through the activation of neurohormonal cascades in HF, the clinical implications of sustained hyponatraemia and treatment options in the management of this challenging phenomenon.     

Hyponatraemia in elderly psychiatric patients treated with Selective Serotonin Reuptake Inhibitors and venlafaxine: a retrospective controlled study in an inpatient unit

OBJECTIVE: To determine the prevalence of hyponatraemia associated with selective serotonin reuptake inhibitor (SSRI) and venlafaxine use in elderly patients compared to that in elderly patients not prescribed these drugs, while controlling for age, sex, depression status and illnesses or prescribed medications also associated with hyponatraemia. Design and setting Retrospective controlled analysis in a 36-bed inpatient unit for elderly psychiatric patients in Melbourne. PATIENTS: Inpatients (199) with a mean age of 74.2 years of whom 74 were prescribed an SSRI or venlafaxine. RESULTS: Patients on SSRIs or venlafaxine were 5.6 times as likely as patients not so treated to have hyponatraemia. Thirty-nine percent of patients on an SSRI or venlafaxine had hyponatraemia compared with 10% of controls. Ten of the 14 patients on venlafaxine were hyponatraemic. Controlling for thiazide status did not reduce the odds of these patients having hyponatraemia and taking an SSRI or venlafaxine was still strongly associated with hyponatraemia after also controlling for age, sex, and depression status, consumption of other drugs potentially causative of hyponatraemia and medical illness severity (Odds Ratio (OR) 3.5, p = 0.008). CONCLUSIONS: SSRI and venlafaxine use is strongly associated with the presence of hyponatraemia in a population of elderly psychiatric inpatients and the association is not due to confounding by age, sex, depression status, medical illness severity or consumption of other drugs. Elderly patients on SSRIs or venlfaxine should have sodium levels checked before and after commencement of antidepressant treatment.