Hyponatraemia in patients with multiple myeloma.

Hyponatraemia is the most common electrolyte disturbance encountered in clinical practice. Several causes of hyponatraemia are recognised and in many patients the aetiology may be multifactorial. An important cause is water intoxication and this is often iatrogenic. We present three patients, all of whom suffered from multiple myeloma, who illustrate different aspects of hyponatraemia, its causes and management. 2015 BMJ Publishing Group Ltd.