Endocrine Abstracts

Background: Hyponatraemia is the most common electrolyte abnormality, encountered in up to 30% of inpatients. Plasma sodium levels <125 mmol/l are classed as severe and can be associated with drowsiness, confusion, ataxia and personality change. In mild hyponatraemia, the patient is usually asymptomatic, although studies have shown chronic low sodium of any level may be associated with increased mortality and longer hospital stays. Vasopressin receptor antagonist (tolvaptan) are indicated to treat hyponatraemia in patients with SIADH not responding to fluid restriction. In this case series we present our experience with the use of Tolvaptan. Methods:

A retrospective study of all patients treated for SIADH with Tolvaptan. Patient demographics and biochemistry were obtained from the case records. Results: Nine patients were identified who were treated with tolvaptan; and included five males, mean age 74.4±8.5 years. Cause of SIADH were: pituitary tumor (1), Lung cancer (3), Drug induced (1), stroke (2), idiopathic (2). Mean admission serum sodium (S Na) was 120±9 mmol/l. After fluid restriction mean S Na was 122.9±4.2 mmol/l. Following commencement of tolvaptan (15 mg daily) serum sodium at 24, 48–72 h and 1, 2 and 4 weeks were: 128.8±4.3, 133.1±2.8, 133.2±3.8, 133.1±5.5, 133.2±4.7 mmol/l respectively. Mean (range) duration of tolvaptan therapy was 81 (5–180) days. Five patients had S Na >130 in 24 h, and all patients had S Na >130 within 72 h. None of the patients had side effects to tolvaptan. One patient had a greater than recommended increase in serum Na (>12 mmol/l) in 24 h. Conclusion: Patients treated with tolvaptan had rapid improvement in serum sodium levels. Use of tolvaptan was without any adverse events to the treatment.