The background of the study. Hyperthyroidism can cause low bone density, but how much it increases after antithyroid therapy is not clear. In this study bone density was measured in women with hyperthyroidism at the time of diagnosis and up to three decades later.
How the study was done. The study groups were 164 white women with present or past hyperthyroidism caused by Graves’ disease (87 percent) or a nodular goiter (13 percent) and 79 normal women. Among the women with hyperthyroidism, 107 (65 percent) were treated with an antithyroid drug, 49 (30 percent) with radioiodine, and 8 (5 percent) with surgery. Bone mineral density of the femoral neck and lumbar spine (L2–L4) was measured by dual-photon absorptiometry, and the results expressed as Z scores (deviation from values in women of similar age) and T scores (deviation from values in young women).
The results of the study. The 19 women studied
at the time of diagnosis of hyperthyroidism or very soon thereafter
had a lower femoral-neck than lumbar-spine bone density Z score (-0.42 vs.
-0.11). The values were higher in the women studied at longer intervals after antithyroid therapy, and were nearly 0 at both sites in the 96 women studied 3.1 to 31 years after diagnosis.
When considered in relation to age at the time of diagnosis of
hyperthyroidism, the femoral-neck Z score 0 to 3 years later was
-0.26 in 25 women aged 13 to 30 years at diagnosis, and it was 0.40 in those studied 3.1 to 31 years after diagnosis. The respective values in women aged 31 to 50 years at diagnosis were -0.20 and
-0.10, and those in 41 women aged 51 to 70 years at diagnosis were -0.51 and -0.14. The mean lumbar-spine Z scores were similar, with the younger women gaining more bone density with time.
The conclusions of the study. Women with hyperthyroidism may have low femoral neck and lumbar spine bone density, but after treatment it increases to normal at both sites with time.
The original article. Karga H, Papapetrou PD, Korakovouni A, Papandroulaki F, Polymeris A, Pampouras G. Bone mineral density in hyperthyroidism. Clin Endocrinol (Oxf) 2004;61:466-72.