engleski

Bone mineral density in patients on long-term levothyroxine therapy

The aim of the study was to determine the influence of replacement and supressive thyroxine therapy on bone mineral density (BMD). Patients: 30 postmenopausal women, 19 on replacement therapy (dose 1.22 +/- 0.35 ug/kg ; duration 11.4 +/- 7.2 years) and 11 on supressive therapy (dose 1.45 +/- 0.71 ug/kg ; duration 9.5 +/- 7.2 years). The mean age of patients was 60.4 +/- 7.9 years and the mean duration of postmenopause was 12.1 +/- 7.5 years. There was no significant decrease in age and duration of postmenopause between the replacement and the supressive treated groups of patients. Controls were 60 healthy women matched for age and menopausal status. Measurements. serum T3, T4 and TSH were measured and BMD at the lumbar spine (L2-L4), femoral neck, Ward's triangle and trochanter was measured by dual energy X-ray absorptiometry. Forearm BMD at distal site was measured by single-photon absorptiometry. Results: mean thyroid hormone values and TSH were within normal limits, although the patients on supressive therapy had significantly higher T3 (p<0.05) than the patients on replacement therapy. The BMD values are as follows: Patients on Patients on Controls replacement therapy supressive therapy Lumbar spine 0.847+/-0.167 0.981+/-0.104 1.052+/-0.124 Femoral neck 0.815+/-0.111 0.838+/-0.099 0.872+/-0.110 Ward 0.691+/-0.141 0.712+/-0.154 0.765+/-0.765 Trochanter 0.670+/-0.127 0.722+/-0.080 0.738+/-0.128 Radius 0.574+/-0.109 0.581+/-0.098 0.631+/-0.089 BMD on each site, except on trochanter, was significantly lower in the replacement treated group than in controls (p<0.001 spine ; p<0.01 neck ; p< 0.05 Ward, radius). BMD in patients on supressive therapy was lower, but not significantly, comparing to controls. Conclusion: we conclude that the thyroxine therapy, either on replacement or supressive doses has an adverse effects on bone mass. We also speculate that the lower bone loss in the supressive treated group might be a result of the subtle resistance to the thyroid hormones.

levothyroxine; bone mineral density; hypothyreosis

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