Renal Function Is Associated with Changes in Bone Mineral Density in Postmenopausal Osteoporotic Women Treated with Denosumab: Data From a Retrospective Cohort Study

<b>Background/Objectives</b>: Renal function influences bone metabolism, as kidney failure can increase the risk of fractures. Denosumab is an approved osteoporosis treatment, but its efficacy in relation to renal function has not yet been studied in real-life scenarios. This study aimed to investigate the denosumab-induced change in bone mineral density (BMD) according to kidney function. <b>Methods</b>: A retrospective analysis was conducted at the outpatient clinic in postmenopausal women receiving denosumab (60 mg subcutaneously administered every 6 months). The glomerular filtration rate (eGFR) was measured by the 2021 CKD-EPI equation and patients were stratified for eGFR categories. BMD was measured by dual-energy X-ray absorptiometry. <b>Results</b>: 128 women (mean age 70.3 ± 9.4 years) were recruited. The mean denosumab treatment duration was 3.9 ± 1.4 years and all the participants had improved BMD values. In stepwise multiple regression analysis-after controlling for age, BMI, and treatment duration-the eGFR value (ß = -0.11, SE 0.04, <i>p</i> = 0.01) was independently associated with the lumbar spine BMD change. The same association remained when the eGFR categories were considered (ß = 3.564, SE 1.29, <i>p</i> = 0.007). In addition, after controlling for BMI and the duration of denosumab treatment, age (ß = -0.7915, SE 0.37, <i>p</i> = 0.03) and eGFR (ß = -0.3257, SE 0.1567, <i>p</i> = 0.04) were found to be associated with femoral neck BMD change. The association remained when considering eGFR categories (ß = 8.7339, SE 4.29, <i>p</i> = 0.04). <b>Conclusions</b>: This retrospective study suggests that eGFR is associated with denosumab efficacy in postmenopausal women treated for osteoporosis.