Changes in Bone Mineral Density Following Levothyroxine Therapy in Hypothyroidism – A Prospective, Observational Study

Background/Objective Thyroid hormones play a significant role in skeletal metabolism and bone turnover. We investigated the effect of levothyroxine (LT4) replacement on bone mineral density (BMD) using dual-energy X-ray absorptiometry (DEXA) in newly diagnosed patients with hypothyroidism. Methods In this prospective, observational study, we included 70 adult patients newly diagnosed with either overt (OH) or subclinical hypothyroidism (SCH). LT4 was initiated at 1.6 μg/kg/day and 25 μg/day in OH and SCH, respectively, and the dose was adjusted every two months to achieve euthyroidism. BMD was done at baseline and two months after attaining euthyroidism. The results were analysed using appropriate statistical methods, and a p-value of less than 0.05 was considered significant. Results The study participants (51F; 19M) had a mean age of 36.6 ± 10.7 years, body weight of 63.5 ± 13.6 kg, and a body mass index 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 LT4 therapy to achieve euthyroidism was 7.3 ± 2.2 months. The BMC (gm) during hypothyroidism (1828 ± 345.6) changed significantly after achieving euthyroidism (1883 ± 350.8) (p=0.0004). Similar benefit was seen in the Z score of the lumbar spine and femoral neck (p