PEDIATRICS Vol. 106 No. 5 November 2000, pp. 1137-1138

COMMENTARY:
Depot Medroxyprogesterone Acetate in Teens: A Risk for Bone Health?

We read with interest the recent review by the AAP's Committee on Adolescents entitled "Contraception and the Adolescent."¹ "Reversible osteopenia" was mentioned as a possible adverse effect of depot medroxyprogesterone acetate (DMPA, marketed as Depo Provera, Pharmacia & Upjohn, Kalamazoo, MI). As clinicians and researchers, we are aware that concern about the effects of DMPA on bone mineral has led some practitioners to avoid DMPA use in adolescents. We believe it would be helpful to review the data and controversies linking DMPA and osteopenia.

DMPA works as a contraceptive by inhibiting pituitary gonadotropin secretion, which suppresses both ovulation and ovarian estrogen production. Concern about the skeletal effects of reduced serum estrogen has prompted studies of bone mineral. Several cross-sectional surveys have found lower bone density in long-term DMPA users than nonusers; the effects were most marked in younger women.^2-4 Two small prospective studies in teenage girls (average age 15) have also shown a decrease in spinal bone density with DMPA injections.^5,6 The actual losses (1.5%-1.8% in the first year and 3.1%-3.8% by the end of the second year of use) were modest but worrisome because bone mineral was increasing in teens females who used oral contraceptive or levonorgestrel (Norplant, Wyeth-Ayerst Laboratories, Philadelphia, PA) were gaining bone mineral.

The studies in adolescents can be criticized for their small size and the failure to control for confounding risk factors such as age, race, smoking, nutritional status, physical activity, and history of teen pregnancy. There is an urgent need for larger prospective studies to explore the effects of DMPA on bone mineral in women of all ages. If bone loss is documented with DMPA, we need to determine if the deficit is recoverable after stopping the medication, as it appears to be in adults.⁷ The potential benefit of adding back estrogen in DMPA users warrants investigation as well. Fortunately, well-designed studies to address these questions are underway in the United States and New Zealand, but it will be several years until results are available.

We believe it would be premature and irresponsible to suspend all use of DMPA in adolescents while we wait for these data. To remove this effective and easily administered contraceptive method would likely result in more unwanted pregnancies. The impact of teen pregnancy on the growing skeleton may also take its toll on peak bone mass and the psychological costs of maintaining or terminating a pregnancy are significant. These risks must be weighed against the potential risks of DMPA. For young women with skeletal risk factors such as anorexia nervosa, malabsorption, or a family history of osteoporosis, DMPA may not be the best choice.

The best means of monitoring and fostering bone health during DMPA use is similarly controversial. Routine assessment of bone mineral density cannot be endorsed because the typical duration of DMPA use is <1 year. For those young women who have preexisting risk factors for osteopenia or those who remain on DMPA for >1 year, it may be reasonable to assess skeletal status with dual energy x-ray absorptiometry or bone ultrasound. DMPA users should be encouraged to avoid smoking, optimize calcium and vitamin D intake, and engage in weight-bearing physical activity, because these lifestyle variables may add as much as 5% to 10% to peak bone mass.⁸

CONCLUSION

We have much to learn about the effects of DMPA, but it is premature to eliminate this method of contraceptive in teens. The concern raised about pediatric bone health is laudable and one that will hopefully lead to additional research and intervention efforts for all adolescents.

Laura K. Bachrach, MD
Department of Pediatrics
Stanford University School of Medicine
Stanford, CA 94305-5208

Tim Cundy, MD
Department of Medicine
University of Auckland
Auckland 1, New Zealand

Susan M. Ott, MD
Department of Medicine
University of Washington School of Medicine
Seattle, WA 98195-6426

FOOTNOTES

Received for publication Jan 3, 2000; accepted Feb 7, 2000.

Reprint requests to (L.K.B.) Division of Pediatric Endocrinology, Room S302, Stanford Medical Center, Stanford, CA 94305-5208. E-mail: lkbach{at}leland.stanford.edu

ABBREVIATIONS

DMPA, depot medroxyprogesterone acetate.

REFERENCES

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