14. Hyperthyroidism In Pregnancy-A Review

Balram Sharma, Shruti Sharma

ABSTRACT

The changes in thyroid gland physiology induced by pregnancy must be differentiated from hyperthyroidism. Hyperthyroidism during pregnancy is not very common with reported incidence of 0.05–3.0% with Graves’ disease accounting for 85% of cases. Gestational transient thyrotoxicosis is typically reported in women with hyperemesis gravidarum, and is mediated by high circulating concentrations of human chorionic gonadotropin. The exact diagnosis of the cause of hyperthyroidism in pregnancy should be determined as outcomes for both the mother and the child and the treatment depend on the cause. Antithyroid drug therapy to treat hyperthyroidism in pregnant women is considered controversial because the usual drugs (methimazole or carbimazole)are considered safe, but has found to be teratogenic in some reports; and the alternative(propylthiouracil) is safe in terms of foetal side effects but can have some hepatotoxic potential. Propylthiouracil (PTU) is recommended as the first line drug for treatment of hyperthyroidism during the first trimester of pregnancy and should be changed to either methimazole or carbimazole after the completion first trimester. The maternal free T4 level should be maintained at the upper limit of the non-pregnant reference range. Fetal monitoring should be done with the fetal ultrasound at 18th to 22nd week in women who are TRAb positive. Antithyroid drugs are also recommended for hyperthyroidism in the postpartum period and for women who are breastfeeding.

Key-words: Gestational transient thyrotoxicosis, hyperemesis gravidarum, congenital malformations, thyrotoxic crisis.

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