Effect of Levothyroxine on Visceral Adipose Tissue-A Prospective, Observational Study

Hypothyroidism is a common condition, and thyroid hormones play a key role in metabolism and fat regulation. We examined how levothyroxine affects visceral adipose tissue (VAT) and body composition using dual-energy X-ray absorptiometry in newly diagnosed hypothyroid patients.

In this prospective observational study, we enrolled 70 adult patients newly diagnosed with either overt hypothyroidism (OH) or subclinical hypothyroidism (SCH). Levothyroxine was started at 1.6 µg/kg/day for OH and 25 µg/day for SCH, with doses adjusted every 2 months to reach euthyroidism. Body composition and VAT were assessed at baseline and 2 months after achieving euthyroidism. Results were analyzed using appropriate statistical methods, and a P value of less than 0.05 was considered significant.

The study participants (51 F; 19 M) had a mean age of 36.6 ± 10.7 years, body weight of 63.5 ± 13.6 kg, and a body mass index (BMI) of 25.5 ± 4.2 kg/m 2 . A total of 46 (66%) patients had OH, and 24 (34%) patients had SCH. The mean duration of levothyroxine therapy to achieve euthyroidism in both groups was 7.3 ± 2.2 months. The VAT (gm) did not show a significant change (before 584.7 ± 266.6 and after 596.8 ± 265.3) after achieving euthyroidism ( P = 0.1283). No significant difference was seen in either fat mass or lean mass.

Levothyroxine did not significantly alter body composition or VAT during this short observation period. Additional studies with a larger sample size and longer-term follow-up are needed to confirm our findings.