Low BMD likely in postmenopausal women with Graves’ disease

Most postmenopausal patients with Graves’ disease had low bone mineral density while in the hyperthyroid state, according to recent study findings presented at the 15th International Thyroid Congress and 85th Annual Meeting of the American Thyroid Association.

“Thyrotoxicosis results in increased bone turnover, shortening of the bone remodeling cycle and reduced BMD,” the researchers wrote. “Treatment of thyrotoxicosis can normalize BMD in males and premenopausal females, but there have been few reports on changes in the BMD of postmenopausal hyperthyroid patients in response to treatment.”

Ai Yoshihara, MD, PhD, and colleagues from Ito Hospital in Tokyo evaluated 85 postmenopausal women with newly diagnosed Graves’ disease to determine BMD and bone turnover markers among them.

DXA was used to measure BMD of the lumbar vertebrae, both femurs and left distal forearm. Before treatment with antithyroid drugs and at 6, 12, 18 and 24 months after reaching a euthyroid state, all patients had body height, body weight, BMD, serum thyroid hormone levels and bone turnover marker levels measured. However, no significant differences were found for serum thyroid hormone and thyrotropin-receptor antibody titer levels between the osteoporosis group and those with normal BMD.

At 1 year after achieving a euthyroid state, participants with osteoporosis had improved to osteopenia and half achieved osteopenia by 2 years and one had normal BMD.

Fractures did not occur in any participants during the study period.

Before treatment, 22.3% of participants had normal BMD, whereas osteopenia was indicated in 31.8% and osteoporosis was indicated in 45.9%. Compared with the normal BMD group, the osteoporosis group was significantly older, had lower BMI, higher serum alkaline phosphatase (ALP), bone ALP and serum type I collagen cross-linked N-telopeptide values.

“In this study, 77% of the postmenopausal [Graves’ disease] patients had low BMD in the hyperthyroid state,” the researchers wrote. “A low BMI and high serum ALP level are good indications for measuring BMD. The BMD of the hyperthyroid patients with osteoporosis had increased after being maintained in a euthyroid state with [antithyroid drugs] for 2 years.” – by Amber Cox

Reference:

Yoshihara A, et al. Poster 162. Presented at: 15th International Thyroid Congress and 85th Annual Meeting of the American Thyroid Association (ITC/ATA); Oct. 18-23, 2015; Lake Buena Vista, Fla.

Disclosure: Yoshihara reports no relevant financial disclosures.