Psychogenic polydipsia is an uncommon clinical disorder characterized by excessive
water-drinking in the absence of a physiologic stimulus to drink. The excessive
water-drinking is well tolerated unless hyponatraemia supervenes (1). The level
of hyponatraemia used in one study was below 130 mmol/L (2). Classically this
disorder has been described in hospitalised schizophrenics. Also it may occur
in children, as a symptom of emotional difficulties or as an isolated phenomenon
in a child who simply enjoys drinking.
The diagnosis of psychogenic polydipsia is one of exclusion and requires specialist
investigation and management; the most important test is the water deprivation
test which should be undertaken carefully. Note that chronic psychogenic polydipsia
may actually impair the response of the kidneys to ADH, and therefore reduce
the renal concentrating ability. Equivocal results should be interpreted with
Clozapine is an atypical antipsychotic drug that has been demonstrated to be
a highly effective treatment for polydipsia in schizophrenic patients. There
has also been the successful use of clozapine in psychogenic polydipsia in a
non-schizophrenic patient (3).
polydipsia with hyponatremia: report of eleven cases. Am J Kidney Dis. 1987
Intern Med. 1995 May 8;155(9):953-7.
Psychopharmacol. 2002 Jul;17(5):253-5.