Only mothers with severe Graves' disease
give birth to infants with hyperthyroidism
(November 2002)
The background of
the study. Fetuses and neonates of mothers who have Graves'
disease may have hyperthyroidism, caused by the transplacental passage
of thyrotropin (TSH)-receptor-stimulating antibodies. This study
was done to determine the relationship between maternal serum concentrations
of these antibodies and the risk of fetal or neonatal hyperthyroidism.
How the study was done. Serum TSH-receptor-stimulating
antibodies were measured during the second trimester of pregnancy
in 61 women with a history of Graves' disease. Among the 49 women
who had positive tests for the antibodies, prenatal and delivery
records were available for review in 29 (59 percent). Neonatal hyperthyroidism
was defined as symptoms and signs of hyperthyroidism (tachycardia,
goiter, irritability, hyperphagia, heart failure) and high serum
free thyroxine and low serum TSH concentrations.
The results of the study. The 29
women (mean age, 29 years) had 35 singleton pregnancies ending with
live births. During these pregnancies, 11 women were treated with
propylthiouracil, 8 with thyroxine for hypothyroidism caused by
radioiodine treatment or surgery, 6 with propylthiouracil and thyroxine,
and the remainder with neither treatment. Among the 35 infants,
6 (17 percent) had neonatal hyperthyroidism, including two infants
delivered by each of two mothers. Five of these 6 infants had tachycardia
and 2 had heart failure; all were treated with propylthiouracil.
Among the mothers of these 6 infants, all (100 percent) had serum
TSH receptor-stimulating antibody values more than five times the
upper limit of normal. Among the 29 normal infants, the mothers
of only 6 (21 percent) had serum values more than five times the
upper limit of normal.
The conclusions of the study. Among
pregnant women with Graves' disease, only the infants of those with
very high serum thyroid-stimulating immunoglobulin index values
are at risk for hyperthyroidism.
The original article. Peleg D, Cada
S, Peleg A, Ben-Ami M. The relationship between maternal serum thyroid-stimulating
immunoglobulin and fetal and neonatal thyrotoxicosis. Obstet Gynecol
2002;99:1040-3.
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