Schizophrenia and fatal self-induced water intoxication with appropriately-diluted urine.

A 31-year-old woman with untreated chronic schizophrenia developed extreme polydipsia which rapidly led to coma and death due to cerebral edema. Hyponatremia (120 mEq/liter) and serum hypo-osmolality (260 mOsm/kg) were associated with marked polyuria (up to 1850 ml/hour) and appropriately low urinary osmolality (90 mOsm/kg) which responded to treatment. This case and few qualifying previous reports which are reviewed support the possibility that pure self-induced water intoxication with no major contribution of inadequate release of antidiuretic hormone may occur, and that extreme polydipsia can sometimes overwhelm normal renal diluting capacity in psychotic patients.