Effect of adjunctive cortisol on serum sodium in a polydipsic hyponatremic schizophrenic patient

1. Many polydipsic schizophrenics exhibit enhanced antidiuretic hormone (ADH) activity and thus are hyponatremic and suffer life-threatening water intoxication. Excess cortisol inhibits ADH, while cortisol insufficiency produces impairments in water balance resembling those seen in hyponatremic schizophrenics. Furthermore, hyponatremia normally upregulates cortisol receptors on the neurons which synthesize ADH, which should make them more sensitive to the effects of cortisol. 2. The author treated a hyponatremic schizophrenic, whose water imbalance was unresponsive to standard clinical interventions including clozapine, with a 4-week open trial of 60 mg cortisol daily, followed by a three week taper. 3. Mean serum sodium levels appeared to increase modestly from 114.3 to 118.5 mEq/l while the patient received adjunctive cortisol (P < .06). 4. While a modest effect was seen, the results do not suggest that adjunctive cortisol will reverse hyponatremia, and instead support other data indicating that these patients exhibit a central resistance to glucocorticoid actions.