Chronic kidney disease is associated with low BMD at the hip but not at the spine.

UNLABELLED: Although chronic kidney disease is associated with other bone disorders, osteoporosis can be found in this context, and it is defined based on bone mineral density (BMD), measured by dual-energy X-ray absorptiometry. As CKD progresses, the percentage of normal BMD decreases, whereas that of osteopenia/osteoporosis increases, mostly due to hip involvement, particularly in patients with reduced renal function.

INTRODUCTION

Osteoporosis is a highly prevalent disease in patients with chronic kidney disease (CKD). We investigated the features of bone mineral density (BMD) in patients with assorted kidney diseases and hypothesized that low BMD, as measured by dual-energy X-ray absorptiometry (DXA), would be more prevalent as kidney function decreased and would correlate with biomarkers of mineral and bone disease.

METHODS

DXA obtained from January 1, 2008, to December 31, 2017, clinical, demographic, and biochemical data at the time of image acquisition were recorded. Data from 1172 patients were included in this study (81.3% women, 79.9% white, and 8.1% diabetic).

RESULTS

Osteopenia and osteoporosis in at least one site (total hip or spine) were found in 32.7% and 20.0% of patients, respectively. As CKD progressed, the percentage of patients with normal BMD decreased, whereas the percentage of osteopenia and osteoporosis increased, which was mostly due to the total hip involvement, particularly in patients with estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2. Older age and hyperparathyroidism were independent risk factors for osteopenia/osteoporosis at the total hip; female gender, older age, and higher iCa were independently associated with the risk of osteopenia/osteoporosis at the spine. With eGFR > 90 ml/min as reference, the odds ratios for osteoporosis/osteopenia at the hip were 1.51 (95% CI 1.01-2.24) and 1.91 (95% CI 1.13-3.20) for patients with eGFR 30-60 and 15-30 ml/min/1.73 m2, respectively. No CKD stage was significantly associated with the risk of osteoporosis/osteopenia at the spine.

CONCLUSION

Our results highlighted that low BMD in patients with CKD is associated with age and hyperparathyroidism, and affects predominantly the hip.