Two-year cortical and trabecular bone loss in CKD-5D: biochemical and clinical predictors.

Abstract

This prospective 2-year study of chronic kidney disease on dialysis (CKD-5D) patients assessed trabecular and cortical bone loss at the hip and spine and examined potential demographic, clinical, and serum biochemical predictors of bone loss. Eighty-nine CKD-5D patients had baseline, year 1, and year 2 bone mineral density (BMD) measurements using dual X-ray absorptiometry (DXA) and quantitative computed tomography (QCT); concurrent blood samples were drawn and clinical variables recorded. No study treatments occurred. The 2-year total hip BMD change was -5.9% by QCT and -3.1% by DXA (p<0.001). Spinal BMD was unchanged. QCT total hip cortical mass and volume decreased (-7.3 and -10.0%); trabecular volume increased by 5.9% (ps<0.001). BMD changes did not vary with age, BMI, race, diabetes, smoking, or exercise. Patients with higher baseline BMD and shorter dialysis vintage lost more bone (p<0.05). Vitamin D analogs and phosphate binders were not protective against bone loss; cinacalcet was protective by univariate but not by multivariable analysis. CNS-affecting antihypertensives were protective against loss of BMD, cortical mass, cortical volume (ps<0.05) and trabecular mass (p=0.007). These effects remained after adjustment. BSAP correlated with changes in BMD, cortical mass, and volume (p<0.01) as did sclerostin (inversely). There was severe cortical bone loss at the hip best recognized by QCT. Patients with shorter dialysis vintage and less pre-existing bone loss lost more bone, while treatment with CNS-acting antihypertensives was protective. BSAP and sclerostin were useful markers of bone loss.