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Education And Debate

Changing perceptions in osteoporosisCommentary: Bone density can be used to assess fracture risk

BMJ 1999; 318 doi: (Published 27 March 1999) Cite this as: BMJ 1999;318:862

Changing perceptions in osteoporosis

  1. Terence J Wilkin, professor (
  1. Plymouth Postgraduate Medical School, University of Plymouth, Plymouth PL4 8AA
  2. Section of Medicine, University of Sheffield Division of Clinical Sciences, Northern General Hospital, Sheffield S5 7AU
  • Accepted 24 November 1998

A recent meta-analysis of 11 separate study populations and over 2000 fractures concluded that bone mineral density “cannot identify individuals who will have a fracture.”1 So why do we measure it? The question is worth asking when the number of dual energy x ray absorptiometry machines installed in the United Kingdom exceeds 130 (National Osteoporosis Society, personal communication), and the number of Medline citations incorporating the term dual energy x ray absorptiometry has grown from 26 in 1988 to 464 in 1997. The concept of “fracture threshold” has led to the recommendation that preventive treatment be given to women once their bone density lies (arbitrarily) more than 1 SD below the mean for premenopausal women—a state of osteopenia, according to the WHO definition. But should we be managing osteoporosis by numbers?

Summary points

Bone densitometry cannot identify people who will sustain osteoporotic fracture

Bone density changes little with antiresorptive treatment (hormone replacement therapy and bisphosphonate drugs), whereas bone turnover falls dramatically

Bone turnover may be the responsive element in treatments to prevent osteoporotic fracture

Antiresorptive treatments prevent fracture, regardless of whether they are given at the menopause or decades later

Since frequency of impact, which rises exponentially with age, is the main risk factor for fracture, treatment should be focused on infirm older people, irrespective of their bone density

Osteoporosis and osteomalacia

Bone comprises a matrix framework on which mineral is deposited. Osteoporosis is caused by the disintegration of the matrix, and osteomalacia by a failure to mineralise it. When mineralised matrix disintegrates, calcium is inevitably lost. The negative calcium balance observed with matrix loss gave rise to erroneous beliefs that the calcium requirements of postmenopausal women were higher than those of premenopausal women and that osteoporosis could be prevented by calcium supplementation.2 Calcium is crucial during the development of bone, but it …

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