Thyroid Disorders During Pregnancy

Abstract

A 27-year-old woman presented with primary infertility. She had regular menstrual cycles and had no galactorrhea. On evaluation, she was found to have features of thyrotoxicosis and bilateral proptosis. She had grade III diffuse goiter and clinically inactive, and moderate to severe thyroid associated orbitopathy. Her serum T₃ was 2.4 ng/ml (0.8–1.8), T₄ 15.6 μg/dl (4.8–12.6), and TSH 0.01 μIU/ml (0.45–4.2). She was started on carbimazole 30 mg per day, and she achieved euthyroidism within 3 months of therapy, and the dose was reduced to 15 mg per day. She conceived after 11 months of therapy without any assisted reproductive techniques. During her first trimester, she had worsening of symptoms and her serum T₃ was 2.8 ng/ml, T₄ 18.3 μg/dl, and TSH 0.001 μIU/ml. The dose of carbimazole was increased to 30 mg per day. At 4 months of gestation, she attained euthyroidism and the dose of carbimazole was decreased to 15 mg per day which was continued thereafter with regular monitoring of thyroid function tests. She delivered a term baby with a birth weight of 2.45 kg with normal APGAR score. The child was active and was accepting feed normally. Thyroid function of newborn was done on 5th day, which showed a serum T₃ 1.2 ng/ml, T₄ 10.3 μg/dl, and TSH 2.6 μIU/ml. The baby was discharged. At 3 weeks of life, the baby was brought to the hospital with lower respiratory tract infection, and he had weight loss of 0.6 kg despite normal feeding. Examination revealed a pulse rate of 170/min, sunken eyes, and no goiter. Repeat thyroid function test showed serum T₃ 3.5 ng/ml, T₄ 23.7 μg/dl, and TSH 0.005 μIU/ml. He was started on methimazole at a dose of 0.5 mg/kg/day and propranolol at a dose of 2 mg/kg/day, and the child progressively improved with a weight gain of 2 kg over the next 2 weeks. Thyroid function test at 6 weeks showed serum T₃ 0.9 ng/ml, T₄ 7.2 μg/dl, and TSH 1.4 μIU/ml, and the dose of methimazole was tapered to 0.25 mg/kg per day. Six weeks postpartum, mother had exacerbation of symptoms of toxicosis, with a heart rate of 120/min, tremors, and grade III goiter. TAO remained static during pregnancy and postpartum period. Her serum T₃ was 1.8 ng/ml, T₄ 16.5 μg/dl, and TSH 0.05 μIU/ml; the dose of carbimazole was increased to 20 mg/day and β-blocker was added. After 3 months of follow-up, the mother is clinically and biochemically euthyroid and is planned for thyroidectomy in view of large goiter. The baby is growing well and his thyroid function is normal without antithyroid drugs at 3 months.