Clinical Review

Bone loss in young women

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Whether it is depleted by GnRH agonists, athleticism, or glucocorticoids, swift intervention can often restore BMD


 

References

KEY POINTS
  • In young women, many cases of osteoporosis are caused by hypoestrogenism resulting from hormone treatment (eg, GnRH agonists, aromatase inhibitors) or lifestyle adaptations (elite athletics, eating disorders).
  • Treatment of osteoporosis in young women can often be successful with the use of estrogen or “androgenic” progestins.
  • Chronic glucocorticoid treatment is a common cause of clinically significant osteoporosis in young women. Glucocorticoid-induced osteoporosis is an important cause of premenopausal osteoporotic fractures.
  • ObGyns play a key role in ensuring that women enter midlife with strong bones. A focus on young women at very high risk for osteoporosis will help to ensure that our patients build their future bone health on a strong foundation.

ObGyns are very well trained to diagnose and treat women with osteoporosis, most of whom are perimenopausal and menopausal. We are also treating a significant number of young women at risk for osteoporosis because of lifestyle choices or medical treatment of endometriosis or rheumatic diseases. Treatment of this population poses unique challenges and requires specialized approaches.

An important caveat in any discussion of bone loss in young women: Few randomized clinical trials have assessed the efficacy of the various treatments available. In most treatment studies of osteoporosis in young women, bone mineral density (BMD)—an intermediate biometric endpoint—is the primary treatment outcome. In contrast, in the best studies in the menopausal population, the primary treatment outcome is bone fracture—a clinically important endpoint.

In addition, fewer consensus recommendations are available on the management of osteoporosis in young women than for its treatment in menopausal women. In this article, 3 different kinds of cases of bone loss in young women are used to develop key clinical points.

CASE 1 HISTORY

A teen with pelvic pain, bone loss

Therapy eased pain but decreased BMD

A 19-year-old woman has a 3-year history of severe, disabling dysmenorrhea. For 2 years she was treated with nonsteroidal anti-inflammatory drugs and cyclic estrogen-progestin contraceptives before switching to continuous oral contraceptives. These interventions did not relieve her pain. When she was 18, laparoscopy revealed stage I endometriosis, which was resected, providing 6 months of relief. When her pain recurred, the patient was started on leuprolide acetate depot, which caused amenorrhea and provided excellent pain relief. The patient said the leuprolide had “given back her life”. After 6 months of leuprolide therapy, a DXA bone scan demonstrated osteoporosis with a lumbar spine Z score of–2.6.

What treatment do you recommend?

Under age 25, use Z score, not T score

The diagnosis of osteoporosis in very young women is complex and continues to evolve. Physicians have been educated to use the T score (comparison to the mean peak bone mass of young adults) to assess BMD in menopausal women, in whom a decrease in T score of 1 standard deviation is associated with a 2- to 4-fold increase in fracture risk. However, teenage women are often still gaining bone mineral mass as the skeleton develops, so their T scores are normally below that of the peak bone mass of an adult woman. The Z score gives a good comparison of their bone mass with that of teens of the same sex at a similar developmental stage. Most experts agree that, when using DXA test results to assess bone density in women younger than 25, the Z score should be used.1 In one recent study, peak bone mass in the spine was achieved at approximately 23 years of age.2 As women reach age 25, the T and Z scores converge (FIGURE 1).

FIGURE 1 The Z score is more informative when the patient is under 25


The Z score compares the patient with persons of the same age and sex. The T score compares the patient with young normal adults of the same sex. Since bone mass increases until approximately age 20 to 25 years, it is best to use the Z score to evaluate the bone mineral density of women younger than 25 years.1 Reprinted from Gafni RI, Baron J. Overdiagnosis of osteoporosis in children due to misinterpretation of dual energy x-ray absorptiometry. J Pediatr. 2004;144:253–257. ©2004 with permission from Elsevier.

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