Imaging Data From Phase IIIStudy Support Parathyroid as Bone Builder


WASHINGTON — Imaging data from a phase III study confirm that treatment with parathyroid hormone significantly improves bone microarchitecture in postmenopausal osteoporotic women, David W. Dempster, Ph.D., reported in a poster at an international symposium sponsored by the National Osteoporosis Foundation.

The use of micro-CT supports research by Dr. Dempster, professor of clinical pathology at Columbia University, New York, and director of the regional bone center at Helen Hayes Hospital, West Haverstraw, N.Y., and his colleagues on the use of parathyroid hormone (PTH) as a bone builder.

The Treatment of Osteoporosis with Parathyroid Hormone (TOP) study, sponsored by Salt Lake City-based NPS Pharmaceuticals, included about 2,600 women treated daily with 100-mcg injections of PTH or a placebo for 18 months. In addition, all patients received 700 mg of calcium and 400 IU of vitamin D daily. The researchers obtained iliac crest biopsies from women in the PTH and placebo groups.

Based on the micro-CT data, the mean cancellous bone volume was significantly higher (45%) among women treated with PTH, compared with the placebo group. This increase also was associated with 12% and 17% increases in mean trabecular number and thickness, respectively, in the PTH group, compared with the placebo group.

Dr. Dempster and his colleagues had reported similar results when they used histomorphometry to assess iliac crest biopsies in TOP study patients: 48%, 24%, and 17% increases in cancellous bone volume, trabecular number, and trabecular thickness, for the PTH group versus the placebo group.

Although both techniques similarly illustrated improvements in bone volume and thickness in the PTH group, they each contribute some unique information and thus complement each other. Micro-CT is rapid and nondestructive, and provides quantitative information on the 3-D architecture of the bone, while histomorphometry provides details about the impact of PTH on bone turnover and bone cell populations.

Dr. Dempster is a consultant for NPS Pharmaceuticals.

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