Intellectual development and thyroid function in children who were breast-fed by thyrotoxic mothers taking methimazole.
OBJECTIVE
Recent studies have shown normal thyroid function in infants whose mothers receive methimazole (MMI) during breast-feeding. This study evaluates the long-term effect of MMI on thyroid function and intellectual development of such children.


METHODS
Eighty-two children aged between 48 and 86 months were studied. Forty-two children had been breast-fed while their thyrotoxic lactating mothers received daily doses of MMI 20-30 mg in the first, 10 mg in the second and 5-10 mg for additional 10 months of therapy. Thyroid function of infants remained normal during the one year of MMI therapy of their mothers. Forty other infants served as controls. Serum T4, T3, and TSH concentrations, urinary iodine, thyroid antibodies, intelligence quotient (IQ), verbal and functional (performance) components (Wechsler and Goodenough tests) were measured in all children of the two groups.


RESULTS
Height, weight, serum T4, T3, TSH and antithyroid antibody titers were not different between children in the two groups. The mean IQ was 107 +/- 17 vs 106 +/- 16 (Goodenough test) and 103 +/- 10 vs 103 +/- 16 (Wechsler test) for children of thyrotoxic mothers and control children, respectively. There was no difference in verbal and functional IQ and their components between children of thyrotoxic MMI treated mothers and control children.


CONCLUSIONS
Thyroid function and physical and intellectual development of breast-fed infants whose thyrotoxic lactating mothers were treated with 20-30 mg doses of MMI daily are normal at age 48 to 86 months.
Azizi
Fereidoun
F
Endocrine Research Center, Shaheed Beheshti University of Medical Sciences, Tehran, I.R. Iran. azizi@erc-iran.com
Bahrainian
Majid
M
Khamseh
Mohammad E
ME
Khoshniat
Mohsen
M
D001942:Breast Feeding; D002648:Child; D002675:Child, Preschool; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007360:Intelligence / Q000502:physiology*; D007361:Intelligence Tests / Q000592:standards; D007455:Iodine / Q000652:urine; D007518:Isoantibodies / Q000097:blood; D008297:Male; D008713:Methimazole / Q000009:adverse effects / Q000627:therapeutic use*; D009035:Mothers; D011247:Pregnancy; D012189:Retrospective Studies; D013960:Thyroid Function Tests / Q000379:methods; D013961:Thyroid Gland / Q000502:physiology*; D013971:Thyrotoxicosis / Q000188:drug therapy*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood
D007518:Isoantibodies; C035678:anti-Thy antibody; D014284:Triiodothyronine; D008713:Methimazole; D013972:Thyrotropin; D007455:Iodine; D013974:Thyroxine