Body composition changes in patients with differentiated thyroid cancer after iodine-131 treatment and short-term levothyroxine replacement and suppression therapy.

Fat mass decreased in all parts of the body after RAI and short-term LT4 supplementation in DTC patients.

• 57 thyroidectomized DTC patients were included in the study.
• Body composition was measured via dual-energy X-ray absorptiometry before and 4-6 weeks after RAI and LT4 supplementation.
• The range of relative change in fat mass across all body regions was -12.97% to -2.80%.
• Fat mass decreased throughout the body including all measured regions.

Bone mineral content (BMC) increased throughout multiple body regions after RAI and short-term LT4 supplementation.

• Total body BMC increased with a relative change (RC) of 12.12%.
• BMC in the head increased with an RC of 36.23%.
• BMC in the pelvis increased with an RC of 9.00%.
• BMC in the legs increased with an RC of 3.15%.

Bone mineral density (BMD) increased in most body regions after RAI and short-term LT4 supplementation, except in the arms.

• The range of relative change in BMD across different regions was 3.60% to 26.43%.
• BMD did not increase in the arms.
• Measurements were taken via dual-energy X-ray absorptiometry before and 4-6 weeks after treatment.

Lean mass showed region-specific changes, with increases in arms and legs but a decrease in the head, while total lean mass did not change.

• Lean mass in the arms increased with an RC of 4.30%.
• Lean mass in the legs increased with an RC of 3.67%.
• Lean mass in the head decreased with an RC of -2.75%.
• Total lean mass did not change at 4-6 weeks after LT4 supplementation.

Changes in fat distribution in the android region were correlated with changes in lipid indices.

• Changes in android region fat were correlated with changes in total cholesterol (r = -0.390).
• Changes in android region fat were correlated with changes in low-density lipoprotein cholesterol (r = -0.354).
• Both correlations were negative, indicating that greater fat reduction in the android region was associated with greater decreases in these lipid markers.

Changes in lumbar spine BMC and BMD were positively associated with changes in calcitonin levels.

• Changes in lumbar spine BMC were positively associated with changes in calcitonin (r = 0.302).
• Changes in lumbar spine BMD were positively associated with changes in calcitonin (r = 0.325).
• Serum was tested for biochemical indices including thyroid function, lipids, and bone metabolism markers.

The study population consisted of thyroidectomized DTC patients who underwent RAI followed by LT4 supplementation with measurements taken at a short-term follow-up interval.

• 57 thyroidectomized DTC patients were included.
• Body composition parameters were measured before and 4-6 weeks after RAI and LT4 supplementation.
• Serum was tested for biochemical indices of thyroid function, lipids, and bone metabolism.
• Dual-energy X-ray absorptiometry (DXA) was used to measure body composition.