Endocrine Abstracts

We present two thyroid antibody positive euthyroid women with history of recurrent miscarriage who had successful pregnancy outcome when treated with levothyroxine.

A 31-year-old Caucasian lady was referred to our endocrine services with a history of three previous miscarriages. She had strongly positive thyroid peroxidise antibodies (TPO) with normal thyroid function tests.

We commenced her on 25 μg of levothyroxine. Within two months, she conceived and the dose was increased to 50 μg daily. She remained on this dose throughout her pregnancy. Thyroid functions were monitored every 6–8 weeks and had remained normal.

Another 28-year-old Caucasian lady was referred pre-conception with a history of two previous miscarriages. She had normal thyroid function with strongly positive TPO antibodies and family history of primary hypothyroidism.

She commenced 50 μg of levothyroxine and conceived 6 weeks later. She remained on the same dose throughout her pregnancy and her thyroid functions were also monitored every 6–8 weeks.

Both ladies had uneventful pregnancies and delivered successfully at 40 weeks gestation. We aimed for thyroid stimulating hormone (TSH) of 1 mU/l. Levothyroxine was stopped after delivery and thyroid functions remained normal 6 weeks later.

There is a strong association between thyroid antibodies and pregnancy loss. Intervention trials with levothyroxine in thyroid antibody positive euthyroid women with recurrent miscarriage are quite limited but have shown a decrease in the miscarriage rate. The data however is insufficient to recommend for or against routine levothyroxine therapy in thyroid antibody positive euthyroid women during pregnancy.

Such patients are at an increased life time risk of developing primary hypothyroidism and require at least annual monitoring of thyroid function tests and again if they plan to conceive to ensure euthyroidism. Management of these patient and the successful outcomes with levothyroxine treatment adds to the limited evidence in this area.