Bone density in long term users of depot medroxyprogesterone acetate

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Abstract
Objective To identify any adverse effect on bone density in long term users of depot medroxyprogesterone acetate (DMPA) for contraception. Design Cross-sectional measurement of bone density in users with amenorrhoea of more than one year or any woman using DMPA for more than five years. Setting Community Family Planning Clinics in Portsmouth and Manchester. Population One hundred and eighty-five women aged 17–52 years (mean 33.3 years) who had used DMPA for between 1 and 16 years and were attending the clinics for further injections, between August 1994 and August 1996. Methods Dual energy X-ray measurement of bone density of femoral neck and lumbar spine, and venous blood sample taken just prior to the next injection of DMPA. Main outcome measures Bone density of femoral neck and lumbar spine and serum oestradiol in relationship to years of DMPA use and duration of amenorrhoea. Results Most women (n= 153) had serum oestradiol levels < 150 pmol/l. Despite this, the mean bone density of the lumbar spine compared with the population mean for women aged 20–59 years gave a Z score (95% CI) of -0.332 (-0.510 to -0.154). There was no significant difference in the mean density of the femoral neck from the normal population mean. Conclusion Despite amenorrhoea and low serum oestradiol, this sample of long term DMPA users had bone density only minimally below the normal population mean. We therefore found no clinically important adverse effect on bone density and therefore no reason to recommend bone conserving measures, such as add-back oestrogen.