Incidence of Subclinical Hypothyroidism in Obese Adults and Its Metabolic Implications: A Prospective Cohort Study

Subclinical hypothyroidism (SCH) is characterized by elevated thyroid-stimulating hormone (TSH) and normal free thyroxine (FT4) levels. It may also assume the status of comorbidity with obesity and may cause augmented dyslipidemia, insulin resistance, and cardiovascular disease. The aim of the current study was to estimate the prevalence of SCH and its association with the metabolic aberrations in obese adults.

In this prospective cohort study, the random sampling method was used to recruit 200 obese adults (body mass index (BMI) 30 kg/m² and above) who were tested during six months in Shaikh Zayed Hospital, Lahore, Pakistan. The clinical and demographic data of the anthropometric measurements were also recorded. The laboratory tests were interpreted to identify serum TSH, FT4, fasting blood glucose, lipid profile, and insulin resistance calculated through the homeostatic model assessment of insulin resistance (HOMA-IR). SCH featured TSH.4.5 mIU/L with normal FT4. The data were analyzed by using the chi-square test, independent t-tests, and Pearson with p < 0.05.

SCH was present in 41.0% (82/200) of obese adults. SCH patients had significantly greater BMI, fasting glucose, HOMA-IR, total cholesterol, and LDL-C (all p < 0.05) but lower levels of HDL-C (p = 0.004). TSH showed positive correlations with BMI (r = 0.32), HOMA-IR (r = 0.41), and lipid abnormalities and a negative correlation with HDL-C (r = -0.22, p = 0.046).

SCH was seen to be more common in obese adults and was strongly associated with poor metabolic phenotypes. Thyroid screening within the early years of obese patients would facilitate an appropriate early diagnosis and treatment process to mitigate cardiometabolic risk.