A Weekly Roundup of News, Features and Commentary : Thyroid Drug, Osteoporosis

Younger women taking a commonly prescribed thyroid hormone may be at increased risk for bone-thinning osteoporosis if they are treated with too high a dose for a long period of time.

The drug, called L-thyroxine or L-T4, apparently lowered hip bone density by 10% to 13% in 31 premenopausal women who had been taking it for more than five years for their thyroid conditions, researchers from the University of Massachusetts Medical School in Worchester reported last week in the Journal of the American Medical Assn.

While noting that the women in their study were taking doses of L-T4 that would now be considered excessive, the researchers urged physicians to carefully monitor doses “to avoid long-term use of dosages that are excessive for the thyroid condition being treated.”

L-thyroxine, marketed as Levothroid and Synthroid, is commonly prescribed to women with thyroid conditions, and the women in the study were taking the drug for well-accepted reasons, the researchers noted.