A pilot study examining short-term changes in bone mineral density among class 3 obese users of depot-medroxyprogesterone acetate

Objective To examine changes in lumbar spine-bone mineral density (LS-BMD) among normal weight (body mass index [BMI] = 18.5-24.9 kg/m²), Class 1-2 obese (BMI = 30-39.9 kg/m²), and Class 3 obese (BMI ≥ 40 kg/m²) women utilising depot-medroxyprogesterone acetate (DMPA). Methods Five normal-weight, five Class 1-2 obese, and five Class 3 obese women received subcutaneous injections of DMPA-SC at baseline and 12 weeks later. Dual Energy X-ray Absorptiometry (DEXA) scans were performed at baseline and 18 weeks after the first injection for determination of LS-BMD and analysis of fat content. Bimonthly oestradiol (E2) levels were measured by immunoassay methods for 26 weeks. Results There were no significant demographic or LS-BMD differences among the three BMI groups. Significant differences at baseline were as expected among the three groups with respect to BMI and associated parameters (mean % total body fat, absolute fat, and weight). When used as their own controls, significant changes in LS-BMD, % body fat and absolute fat determined by DEXA occurred among all three BMI strata. Class 1-2 obese and Class 3 obese women were more likely to experience E2 fluctuations, but short-term changes in LS-BMD were similar. Conclusions DMPA-SC administration affects L-spine bone health similarly regardless of BMI status.