Introduction: The results of studies examining the influence of subclinical hypothyroidism (SCH) and levothyroxine (L-T₄) replacement therapy on bone have generated considerable interest but also controversy. The present research aims to evaluate the effects of L-T₄ treatment on different skeletal sites in women.
Material and methods: A group of 45 premenopausal (mean age: 43.62 ±6.65 years) and 180 postmenopausal (mean age: 59.51 ±7.90 years) women with SCH who were undergoing L-T₄ replacement therapy for at least 6 months were compared to 58 pre- and 180 postmenopausal women with SCH (untreated) matched for age. The mean doses of L-T₄ were 90.88 ±42.59 µg/day in the premenopausal women and 86.35 ±34.11 µg/day in the postmenopausal women. Bone measurements were obtained using quantitative bone ultrasound (QUS) for the phalanx, dual-energy X-ray absorptiometry (DXA) for the lumbar spine and hip, and peripheral quantitative computed tomography (pQCT) for the non-dominant distal forearm.
Results: No differences were observed between patients and untreated controls in these bone measurements except in the bone mineral density (BMD) of the spine (p = 0.0214) in postmenopausal women, which was greater in treated women than in untreated controls.
Conclusions: Our results indicate that adequate metabolic control through replacement treatment with L-T₄ in pre- and postmenopausal women does not affect bone mass.