Bone Mineral Density in Chronic Kidney Disease Use and Misuse

Low bone mineral density (BMD) is a strong risk factor for low trauma fractures in the postmenopausal population without known chronic kidney disease (CKD). In stage 1?C3 CKD, low BMD can also be used to predict fracture risk with the gradient of risk similar to patients without CKD even though patients with stage 3 CKD have an approximate doubling of risk compared with age-matched patients without CKD. This greater risk of fracture in stage 3 CKD is not calculated in the current FRAX model. In stage 4?C5 CKD, BMD by dual-energy x-ray absorptiometry (DXA) is a poor predictor of fracture risk probably related to the severe derangements in bone metabolism in severe CKD, which alter bone quality and strength not measured by DXA. Serial BMD by DXA, however, may be useful in all stages of CKD to monitor for potential loss of BMD or effect of pharmacological agents to improve BMD. Newer radiological technologies, particularly high-resolution peripheral quantitative computerized tomography (HRpQcT) of the radius and tibia show promise to define the microstructural changes in bone that explain the greater risk of fracture observed in patients with CKD versus patients without CKD. BMD by DXA may still be of value across the spectrum of CKD, but physicians should realize its limitations and understand the greater risk of fracture in patients in all stages of CKD as compared to age-matched and BMD-matched patients without CKD.