Effects of carbamazepine on serum electrolytes in affectively ill patients

The effects on serum electrolytes of carbamazepine, an acute and prophylactic treatment for manic-depressive illness, were assessed in subjects with primary affective disorder. Carbamazepine caused statistically significant, but clinically insubstantial, reductions in serum sodium and calcium, but not in the other electrolytes measured. Decreases in serum sodium and calcium were not related to carbamazepine dose, blood levels, or the degree of clinical improvement. The theoretical implications of these findings are discussed.