There is not enough evidence to recommend for or against routine screening of BMD in long-term users of DMPA.
The Society of Adolescent Medicine has produced clinical guidelines for treating adolescents who do well on DMPA for contraception (SOR: C, expert opinion).22 The guidelines recommend, among other things, that physicians:
continue prescribing DMPA to adolescent girls needing contraception, while providing adequate explanation of benefits and potential risks.
consider ordering a dual-energy x-ray absorptiometry (DEXA) scan to evaluate a patient’s risk.
keep in mind that duration of use need not be restricted to 2 years.
recommend 1300 mg calcium plus 400 IU vitamin D and daily exercise to all adolescents receiving DMPA.
consider estrogen supplementation in those girls with osteopenia (or those at high risk of osteopenia who have not had a DEXA scan) who are otherwise doing well on DMPA and have no contraindication to estrogen.
The World Health Organization similarly published recommendations stating that no restriction should be placed on the use of DMPA due to bone effects (SOR: C, expert opinion).23
Formulate a reasonable approach
As with any other potentially harmful medication, weigh the risks and benefits of DMPA for the individual patient. It is unclear whether BMD lost during DMPA use completely recovers or even what the time frame for that recovery is. Whether the potential risk for future fracture is increased is unknown, but it certainly is cause for concern. Discuss potential risks with any woman who wants to use DMPA for contraception. Routine calcium and vitamin D supplementation for women using DMPA may be helpful and is unlikely to be harmful.
How this systematic review was conducted
A search of PubMed, the Cochrane database, and all references from primary reviewed articles was performed in 2007 using the terms depot-medroxyprogesterone acetate, bone mineral density, osteoporosis, osteopenia, injectable contraception, progestin-only contraception, Depo-Provera, and DMPA. Studies qualified for analysis if they contained data about bone density in women who had used some type of progestin-only injectable contraception. All types of studies were included. Excluded were studies that did not use BMD as an outcome measure or that re-analyzed data published elsewhere.
Bone mineral density is traditionally used as a surrogate measure of fracture risk in postmenopausal women. However, most of the women included in the reviewed studies were young and at low risk of fracture. The relationship between bone density in premenopausal women and fracture risk later in life is unclear. There are no available studies relating injectable progestin-only contraception with future osteoporotic fractures.
There is not enough evidence to recommend for or against routine screening of BMD in long-term users of DMPA. Research should evaluate the efficacy of estrogen supplementation in women on prolonged DMPA. Long-term studies could provide more information regarding BMD recovery over several years.
Correspondence Sarina Schrager, MD, MS, Department of Family Medicine, University of Wisconsin, 777 South Mills Street, Madison, WI 53715; sbschrag@wisc.edu
