Thyroid function in pregnant women with gestational diabetes: Is screening necessary?

Abstract

Background: The goal of prenatal care is mother's and baby's health. Pregnancy is the time of hormonal changes, which cause endocrine disorders in pregnant woman encountering risk to the mother and fetus. Two important and more common problems in pregnancy are gestational diabetes mellitus (GDM) and thyroid disorders. Approximately 1.1-14.3% of pregnant women suffer from GDM and hypothyroidism affects 2.5-6.47% of them. There are some recommendations for diagnosis and screening of GDM but there is no clear advice about the need for performing thyroid function tests during pregnancy. In this study, we aimed to evaluate the need for measurement of thyroid function tests in pregnant women with GDM. Materials and Methods: In this case-control study, 210 pregnant women (105 with and 105 without GDM) were enrolled during 2011-2012 and serum levels of free thyroxine (FT4) and thyroid-stimulating hormone (TSH) were compared between two groups. Results: Mean TSH levels in case and control groups were 3.43 ± 2.06 and 1.74 ± 1.47 μIU/mL, respectively and was statistically higher in case group (P = 0.023). Mean FT4 levels in case and control groups were respectively 1.41 ± 0.69 and 1.5 ± 0.61 ng/dL, which were not statistically different in both groups (P = 0.67). Among patients with GDM, 18 (17.1%) had subclinical hypothyroidism and 11 (10.48%) had clinical hypothyroidism, while among non-GDM patients, 7 (6.66%) had subclinical hypothyroidism and 4 (3.81%) had clinical hypothyroidism. Conclusion: In patients with GDM, hypothyroidism (clinical and subclinical) was obviously higher, the mean serum TSH level was higher in these women, and it was within a range that required treatment. So, it is suggested considering screening and treatment of hypothyroidism in patients with gestational diabetes.