Bone mineral density in premenopausal women receiving levothyroxine suppressive therapy

Osteoporosis is a well-known complication of thyrotoxicosis. Prolonged subclinical hyperthyroidism due to L-thyroxine treatment has been associated with reduced bone mass and thus with the potential risk of premature development of osteoporosis.The aim of this study was to assess the effect of a chronic L-thyroxine suppressive treatment on bone mineral density (BMD) in agroup of premenopausal women. Forty consecutive patients (mean age ± SE = 40.95 ± 1.56 years) affected by non-toxic goiter underwent bone mineral densitometry (dual energy X-ray absorptiometry; DEXA) of the lumbar spine (L1-L4) and right femoral neck. At the time of the study the patients had been under thyroid stimulating hormone (TSH) suppressive therapy for 74.95 ± 10.34 months (range 17-168 months). Baseline levels of free thyroxine (fT4), free triiodothyronine (fT3), TSH, calcium and phosphorus were measured and correlated with BMD. The age of starting, duration of treatment, main daily dose, cumulative dose of treatment and body mass...