HYPONATREMIA AND THE SYNDROME OF INAPPROPRIATE ANTIDIURETIC-HORMONE SECRETION ASSOCIATED WITH DRUG-THERAPY IN PSYCHIATRIC-PATIENTS

Hyponatraemia, the most common electrolyte disorder of all hospitalise d patients, is particularly common in psychiatric patients. Hyponatrae mia is generally defined as a serum sodium level of less than 135 mmol /L. Certain psychotropic medications may predispose to hyponatraemia; yet a causative role for mast has not been firmly established and thei r effect is most likely to be idiosyncratic. Certain factors such as a ge, schizophrenia and a history of hyponatraemia or polydipsia should alert the clinician to the need for closer follow-up. Although the maj ority of cases of hyponatraemia associated with psychotropic medicatio ns occur soon after initiation of the medication, some may occur much later. Thus, it is imperative to check a serum sodium level whenever p atients who are receiving psychotropic medications have a marked chang e in their underlying disease, significant increases in bodyweight, se izures or other symptoms of hyponatraemia. Immediate treatment of hypo natraemia includes discontinuation of psychotropic drugs associated wi th hyponatraemia whenever possible, and treatment should be tailored t o the underlying cause. Rapidity of correction should be determined by the chronicity of the hyponatraemia and whether the patient is sympto matic from the hyponatraemia. Strict adherence to guidelines for corre ction should be observed to prevent brain damage from pontine and extr apontine myelinolysis. Treatment of chronic hyponatraemia is best focu sed on the underlying psychiatric disorder. Overall, adherence to guid elines for early diagnosis and appropriate treatment of hyponatraemia will prevent mortality and reduce morbidity.