Drug-induced syndrome of inappropriate antidiuretic hormone secretion

Abstract

Drugs are a common cause of electrolyte abnormalities, and a careful drug history is essential in patients in whom these are demonstrated. One of the more common electrolyte abnormalities that may be drug-induced is hyponatraemia. A 50-year-old woman was admitted to hospital complaining of nausea, diarrhoea and abdominal pain. Her medical history included depression, alcoholism and laryngeal carcinoma treated by laryngectomy and radiotherapy. Her drug therapy on admission was atenolol 50 mg and loprazolam 1 mg, each once daily; sertraline 50 mg daily had been started 2 weeks prior to admission. On examination she was thin but not clinically dehydrated. She was apyrexial with a blood pressure of 145/100 mmHg and a pulse of 100 beats/min. She had dry skin and palmar erythema. Abdominal examination was normal. There was no neurological deficit. Chest X-ray, full blood count and clotting were normal, except that the mean corpuscular volume was 104 fl (normal range 78–98 fl). Her erythrocyte sedimentation rate was 30 mm/h, sodium 129 mmol/l (132–144), potassium 3.8 mmol/l (3.5–5.0), urea 5.6 mmol/l, creatinine 98 μmol/l and gamma-glutamyl transferase 151 U/l (5–35). …