Severe hypernatraemia (221 mEq/l), rhabdomyolysis and acute renal failure after cerebral aneurysm surgery.

Hypernatraemia is a relatively frequent electrolyte abnormality in hospitalized patients, with reported incidences ranging from 0.65 to 2.23% [1]. Normally, when the serum sodium rises, thirst develops and antidiuretic hormone (ADH) is secreted. Hypernatraemia will not occur in individuals with an intact thirst mechanism and free access to water, due to a potent osmolar stimulus to drink. Hypothalamic injuries may impair the function of the thirst regulatory centre, causing hypodipsia and hypernatraemia [2,3]. Severe hypernatraemia is a serious condition with a mortality of 60% [1,4]. We describe a case of a patient surviving extremely severe hypernatraemia (221mEq/l sodium), rhabdomyolysis and acute renal failure (ARF) associated with hypodipsia and partial central diabetes insipidus after surgery to repair an aneurysm of the anterior communicating artery. Such severe hypernatraemia is unusual and there are few reported cases with serum sodium >200mEq/l [5–8].