Impact of levothyroxine treatment on body weight in drug-naïve primary hypothyroidism: A hospital-based prospective cohort study

Introduction: Very few studies have assessed the impact of treatment of primary hypothyroidism on weight. Materials and Methods: Newly diagnosed primary hypothyroidism cases (overt and subclinical) were enrolled prospectively and started on levothyroxine, and the primary objective of the study was to assess the effect of adequate treatment on weight. Results: A total of 255 participants (190 females and 65 males) completed the study. Sixty-seven participants had subclinical hypothyroidism, and 188 had overt hypothyroidism. Weight decreased in 31.3% of the subclinical hypothyroidism and 56.3% of the overt hypothyroidism subgroups. The median decrease in weight in the group with a decrease in weight was −1.1 kg and −2.1 kg in the subclinical and overt hypothyroidism subgroups, respectively. The multivariate linear regression model predicted weight decrease with a model comprising serum thyroid-stimulating hormone (TSH; P <0.001) and body mass index (BMI; P <0.005) at baseline, with an F -value = 23.8. Conclusion: Baseline serum TSH and BMI predict weight decrease with treatment of primary hypothyroidism.