Bone quality and density improved by parathyroid hormone. (Osteoporotic Men and Women).

CHICAGO -- Parathyroid hormone may soon become the newest addition to the menu of therapeutic options available for the management of osteoporosis in both women and men, Dr. John Bilezikian said at the annual meeting of the American Association of Clinical Endocrinologists.

A handful of recent trials show impressive gains in bone mineral density among osteoporotic patients who underwent 20-40 [micro]/day intermittent therapy with human parathyroid hormone (PTH).

Unlike other antiosteoporotic drugs like alendronate, raloxifene, and calcitonin, which work mainly by preventing further bone resorption, PTH is anabolic. It increases bone mineral density (BMD) by up to 15% in some cases, and seems to improve bone structure by increasing connectivity between trabecular struts within bone, said Dr. Bilezikian, chief of endocrinology at Columbia University, New York.

In the largest multicenter trial to date of PTH therapy for osteoporosis, Dr. Robert Neer and his associates at Massachusetts General Hospital followed 1,637 postmenopausal women with prior histories of vertebral fracture. They were randomized to placebo or treatment with 20 [micro]g or 40 [micro]g daily self-administered injections of PTH and followed for a mean of 21 months.

"The data are very impressive," Dr. Bilezikian said. At both doses, PTH produced a 12%-15% increase in spine BMD. At the femoral neck sites, the increase was considerably lower, but still fairly robust (N. Engl. J. Med. 344[29]:1434-41, 2001). In another study, the gains in vertebral sites tended to plateau by 18 months despite continuous therapy Nonvertebral sites continued to show gains for an additional 6 months (J. Clin. Endocrinol. Metab. 85[9]:3069-76, 2000).

Those who received PTH had a major reduction in vertebral and nonvertebral fractures. At 20 [micro]g/day, the relative risk was 0.35 for vertebral fractures, and 0.46 for nonvertebral fractures. The 40-[micro]g dose gave a slight improvement for vertebral fracture (relative risk 0.31), but did not further reduce the odds of nonvertebral fracture. Leg cramps were the only significant side effect.

Dr. Bilezikian participated in an earlier randomized PTH trial with 23 men, aged 30-68, who had idiopathic osteoporosis. They were randomized to placebo or PTH at 400 U/day for 18 months. The findings in men were essentially the same as those seen in women: a mean BMD increase of 13.5% at the lumbar spine sites, and a 3% ...