The authors assessed 20 carbamazepine-treated patients for the
development of hyponatremia. None of the patients had readings below 135
meg/liter of sodium before carbamazepine therapy, but five (25%) did have
such readings after carbamazepine therapy. Three of these patients
developed frank symptoms of hyponatremia within 1-3 months of the start of
therapy. In one patient, hyponatremia developed after rechallenge with
carbamazepine. The authors suggest that caution be used in prescribing
carbamazepine to patients with low or borderline low sodium values.