Disordered water homeostasis in Asian patients with schizophrenia.

OBJECTIVE

The aim of this study was to determine the prevalence of polydipsia-hyponatremia among patients with schizophrenia in an Asian mental hospital.

METHOD: Seven hundred and twenty-eight inpatients with schizophrenia were assessed for polydipsia-hyponatremia using case notes reviews, specific gravity of urine, normalised diurnal weight gain, and serum sodium levels.

RESULTS

One hundred and three (13.8%) patients had polydipsia, 30 (4.1%) had polydipsia-hyponatremia and 14 (1.9%) had a history of water intoxication. Eight of the 30 patients were receiving carbamazepine, three were on tricyclic antidepressants and two had diabetes mellitus and were on sulfonylureas.

CONCLUSION

The prevalence of water intoxication among polydipsic patients was low compared to Western studies. This could be due to different methods of assessing polyuria, or ethnic differences and/or the prohibition of smoking in our patients. Certain medications might have also contributed to hyponatremia.