RESUMO
Serum concentrations of thyroid stimulating hormone (TSH) and thyroid autoantibodies in pregnant patients with thyroid disease at various stages of pregnancy were determined by in-house ELISAs. In normal pregnancy, serum TSH levels were significantly elevated (p < 0.05) from 13 weeks of gestation. The normal reference ranges for TSH for the second (0.6-5.0 mIU/l) and third trimester (0.6-5.6 mIU/l) were significantly higher (p < 0.05; p < 0.01 respectively) compared to 0.4-4.5 mIU/l for the first trimester. In pregnant thyroid patients, serum TSH levels correlated highly (p < 0.001) to T4 (r = 0.740), FT4I (r = 0.683) and MicAb (microsomal antibodies) (r = 0.825) but weaker (p < 0.01) to T3 (r = -0.512), FT3I (r = 0.520) and TgAb (thyroglobulin antibodies) (r = 0.618). Thus, measurement of TSH with the highly sensitive ELISA (enzyme linked immunosorbent assay) would form a useful first line test for thyroid dysfunction in pregnancy while measurement of thyroid autoantibodies would aid in the diagnosis of autoimmune hypothyroidism.
