Hyponatremia secondary to acute urinary retention.

Acute urinary retention is a rare cause of hyponatremia. Symptomatic acute hyponatremia is of grave medical concern and needs to be managed aggressively. In our two cases with acute urinary retention, a simple bladder catheterization and drainage of urine followed by conservative management resulted in complete resolution of symptoms and normalization of sodium levels. Association of bladder distension and hyponatremia is considered to be due to release of vasopressin triggered by bladder distension itself or by pain due to bladder distension. These cases are presented to bring to light an unusual and easily treatable cause of hyponatremia.