Serum osteoprotegerin measurement for early diagnosis of chronic kidney disease-mineral and bone disorder.

ABSTRACT

AIM: Chronic kidney disease-mineral and bone disorder (CKD-MBD) has been proposed to be the replacement of renal osteodystrophy by the Organization of Kidney Disease Improving Global Outcomes since 2005 because the mineral disorder is not confined to the skeleton in CKD. Accordingly, laboratory and imaging tests have been emphasized for the clinical assessment of patients with CKD besides renal biopsy. The objective of the current study was to investigate whether osteoprotegerin (OPG) could be made a useful biomarker for early diagnosis of CKD-MBD. METHODS: Sixty pre-dialysis patients with CKD 1-5 were enrolled in this study. The serum calcium, phosphorus, blood urea nitrogen, creatinine, alkaline phosphatase, Osteocalcin, Calcitonin, intact parathyroid hormone and OPG were measured. Bone mineral densities of the lumbar spine (L2-L4), femoral neck, Ward's triangle and trochanter were measured by dual-energy X-ray absorptiometry. RESULTS: Among all measured serum bone metabolism indexes, the changing of serum OPG level happened at the earliest time (CKD 3) and its correlation coefficient with estimated glomerular filtration rate (eGFR) was also the highest (r = -0.601, P = 0.001). In the multivariable analysis that included sex, age and eGFR as controlling factors, the serum OPG correlated with the bone mineral density (BMD) of Ward's triangle (r = -0.390, P = 0.041). CONCLUSION: Serum OPG may be a useful biomarker for early diagnosis of CKD-MBD.