Screening of subclinical hypothyroidism during gestational diabetes in Pakistani population

Objective: The increased prevalence of adverse effects of altered thyroid functions in pregnancy inspired us to study the frequency of subclinical hypothyroidism (SCH) and the relationship with glycaemic control and foetal weight in pregnant females with and without gestational diabetes mellitus (GDM) in Pakistani population. Patients and methods: Five hundred and eight pregnant females were enrolled and grouped as per the International Diabetes Association criteria into GDM (n = 208) and healthy control (n = 300). Random blood glucose (RBG), thyroid function tests, anthropometric analysis and foetal ultra sound scans were performed on all study subjects. Data were analysed using Mann-Whitney U test and Chi-square test wherever applicable. Spearman correlation and multiple regression analysis were performed. p values of <0.05 was considered significant. Results: A total of 61.5% GDM subjects depicted SCH with normal circulating T4 and T3 versus 6.0% healthy controls (p-value <0.001). Moreover, TSH remained independently associated with RBG (r = 0.109; p<0.05), poor glycaemic control (r = 0.227; p<0.001) and negatively associated with foetal growth (r = -0.206; p<0.001). Conclusion: The detection of high TSH with normal T3 and T4 in females with GDM strongly emphasises the need of thyroid screening as a routine in all antenatal clinics.