Objectives ? While carbamazepine (CBZ) decreases thyroid hormone concentrations it rarely causes hypothyroidism. We assessed prospectively the early effect of CBZ on thyroid status in thyroxine-supplemented hypothyroid patients, when compared with patients without a thyroid disorder.Conclusions ? In patients with no thyroid disorder, CBZ causes hormonal changes of no clinical relevance, due to adaptive response.
In T4-supplemented hypothyroid patients this adaptation is lacking, CBZ may precipitate subclinical or overt hypothyroidism, and early thyroid function monitoring seems advisable.