Effects of effective antithyroid therapy on adiposity and skeletal muscle in patients with hyperthyroidism across gender and age groups.

OBJECTIVE: The study aimed to evaluate the effects of effective antithyroid therapy on adiposity and skeletal muscle in patients with hyperthyroidism across gender and age groups. PATIENTS AND METHODS: A total of 57 adult hyperthyroid patients (21 males and 36 females) who underwent effective antithyroid medication from January 2018 to January 2021 at Liuzhou People's Hospital and the First Affiliated Hospital of Guangxi Medical University were recruited and followed up for one year to observe the long-term efficacy of the antithyroid therapy. The eligible patients were divided by age and gender groups into male group A (males of <40 years old, n=12), female group A (females of <40 years old, n=19), male group B (males of 40-59 years old, n=8), female group B (female of 40-59 years old, n=13), and group C (patients of ≥60 years old, including one male and four females). A cohort of 57 healthy individuals was also recruited as controls. A Dual Energy X-ray (DXA) was performed to measure changes in fat and lean tissue mass and grip strength of the dominant hand before and after treatment and the body fat percentage (BFP). The whole-body skeletal muscle mass index (ASMI) was calculated to evaluate the long-term effects of antithyroid therapy. RESULTS: The eligible patients of all ages reported significantly increased total fat mass, body fat percentage, and body mass index (p<0.05). The total lean tissue mass was markedly increased in male and female group A (p<0.05), showed no significant changes in male and female group B (p>0.05), and exhibited a marked decline in group C (p<0.05). Significantly elevated ASMI after treatment was observed in male and female group A (p<0.05), while no significant changes were detected in ASMI after treatment in groups B and C (p>0.05). All patients in groups A and B exhibited enhanced grip strength, while the enhancement of grip strength in patients of group C was poor (p>0.05). CONCLUSIONS: Effective anti-hyperthyroidism therapy improves fat mass and body fat percentage in patients of all ages. However, gender and age differences exist in the effectiveness of improvements in total muscle mass and ASMI. Suboptimal muscle mass recovery was reported in patients over 40 years after effective anti-hyperthyroid therapy.