A COMPARISON OF PROPYLTHIOURACIL VERSUS METHIMAZOLE IN THE TREATMENT OF HYPERTHYROIDISM IN PREGNANCY

OBJECTIVE: Our purpose was to demonstrate that propylthiouracil and me thimazole are equally effective and safe in the treatment of hyperthyr oidism during pregnancy. STUDY DESIGN: Between 1974 and 1990 records w ere available on 185 pregnant patients with a history or diagnosis of hyperthyroidism. Ninety-nine patients were treated with propylthiourac il and 36 with methimazole. The response to therapy was compared with respect to the time to normalization of the free thyroxine index and t he incidences of congenital anomalies and hypothyroidism. RESULTS: The time to normalization of the free thyroxine index was compared in the two groups by means of survival analysis. The median time to normaliz ation of the free thyroxine index on propylthiouracil and methimazole was 7 and 8 weeks, respectively (p = 0.34, log-rank test). The inciden ce of major congenital malformations in mothers treated with propylthi ouracil and methimazole was 3.0% and 2.7%, respectively. No neonatal s calp defects were seen. One infant was overtly hypothyroid at delivery . CONCLUSION: Propylthiouracil and methimazole are equally effective a nd safe in the treatment of hyperthyroidism in pregnancy.