Prevalence of thyroid dysfunction and anti-thyroid peroxidase antibody in gestational diabetes mellitus

Background: Gestational diabetes mellitus (GDM) and thyroid dysfunction are the two common endocrine disorders affecting pregnancy. Some association was hypothesized between GDM and thyroid dysfunction in the literature. The main aim of this study was to unveil this metabolic interplay as better understanding may facilitate early diagnosis and intervention thereby limiting major fetal and maternal adverse events. Here we estimated the prevalence of abnormal thyroid function and anti-thyroid peroxidase (anti-TPO) antibody and also studied the risk factors for thyroid disorders in patients with GDM. Materials and Methods: This cross-sectional study was conducted between February 2014 and January 2015. A total of 100 consecutive pregnant women diagnosed to have GDM as per the American Diabetes Association 2013 recommendations were recruited and thyroid stimulating hormone, free triiodothyronine (T3), free thyroxine (T4), and anti-TPO antibody assays were done. Details regarding pregnancy outcome and any complications if present were also obtained and analyzed. The prevalence is expressed as proportions, and the statistical significance of risk factors was assessed using the chi-square test and independent t-test. Results: Abnormal thyroid function was detected in 31 (31%) patients, which includes 17 cases of subclinical hypothyroidism (54%), 10 hypothyroidism (32%), 2 (6%) subclinical hyperthyroidism, and one case each of isolated low T3 and isolated low T4. Anti-TPO antibody was positive in 35 patients (35%). History of GDM in previous pregnancy, family history of diabetes mellitus, presence of clinically detectable thyroid gland enlargement, and presence of anti-TPO antibody in serum were found to increase the risk of thyroid dysfunction. Majority of the subjects had uneventful delivery, and no significant increase in maternal or fetal complications was reported. Conclusions: This study showed a high prevalence of thyroid dysfunction and anti-TPO antibody in GDM patients. The significant thyroid abnormalities detected were subclinical hypothyroidism and hypothyroidism. The risk of thyroid dysfunction is elevated in patients with the presence of anti-TPO antibody. This scenario provides a strong ground to recommend meticulous assessment of thyroid function in GDM patients.