Reports of two cases of autoimmune thyroiditis while receiving anticonvulsant therapy.

Two cases, one a 15-year-old girl and the other a 12-year-old girl, with goitrous hypothyroidism associated with elevated anti-DNA and antithyroid antibodies are reported. Abnormalities were noticed 1 year and 3 months and 5 years after the start of anticonvulsant therapy in case 1 and case 2, respectively. Alternation of drug (Valproate from ethosuximide) in case 1 resulted in disappearance of the goitre, and the thyroid function tests became normal. The titers of the antithyroglobulin and the antimicrosomal antibodies were reduced (below 1:100) from 1:400 and 1:1600, respectively. Discontinuance of anticonvulsant therapy and replacement therapy with desiccated thyroid in case 2 resulted in clinical improvement, reduction of antithyroglobulin antibody from 1:6400 to 1:400 and of antimicrosomal antibody from 1:409,600 to 1:25,600, and the thyroid function tests becoming normal. The present observations suggest that the anticonvulsants may induce or exacerbate autoimmune mechanisms in certain thyroid diseases.