THE PIP SYNDROME - POLYDIPSIA, INTERMITTE NT HYPONATREMIA AND PSYCHOSIS - DIAGNOSIS AND THERAPEUTIC APPROACH - A CASE-REPORT

Polydipsia can be defined as an impulsive behavior leading to absorpti on of large amounts of water (4 to 20 litres a day), without any under lying organic disease. Its prevalence in a population of chronic psych iatric patients can be as high as 6 to 17%. Schizophrenia represents 8 0% of cases reported. Some patients with polydipsia may develop hypona tremia, leading to a PIP syndrome (Polydipsia intermittent hyponatremi a and psychosis). Hyponatremia or water intoxication appears when thre e conditions are present : an abnormal regulation of thirst, an inappr opriate ADH secretion and/or an excessive renal sensitivity to ADH, wi th apr increased sensitivity of the central nervous systeme to hyponat remia. The clinician must first identify patients at risk to develop w ater intoxication and start treatment before any severe physical compl ication occurs. Pharmacological treatments aiming at an increase of re nal free-water excretion - do not show a constant efficacy in the corr ection of hyponatremia, they have no action on polydipsia. The new aty pical neuroleptics such as clozapine and risperidone seem to open new perspectives in the treatment of polydipsia. Controlled studies should be performed in this field.