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What is chronic kidney disease mineral and bone disorder (CKD-MBD)?
Chronic kidney disease mineral and bone disorder (CKD-MBD) is a systemic disorder of mineral and bone metabolism resulting from CKD that may be manifested by either one or a combination of the following:
• Laboratory abnormalities associated with disturbed mineral metabolism, including abnormalities of:
• Calcium
• Phosphorus,
• Parathyroid hormone (PTH)
• Vitamin D metabolites
• Bone disease defined as renal osteodystrophy (ROD) including abnormalities in:
• Bone turnover
• Bone mineralization
• Bone volume
• Bone strength
• Linear growth
• Calcification of extraskeletal tissue, which would include the vasculature and other soft tissues
5 Interesting Facts of Chronic kidney disease mineral and bone disorder
1. Chronic kidney disease–mineral and bone disorder (CKD-MBD) is a systemic disorder of mineral and bone metabolism resulting from CKD that may be manifested by at least one of the following:
a. Laboratory abnormalities associated with disturbed mineral metabolism
b. Bone disease, defined as ROD
c. Calcification of extraskeletal tissue
2. The manifestations of CKD-MBD in the chronologic evolution of CKD are:
a. Phosphate retention
b. Increases in FGF23
c. Decreases in calcitriol
d. Increases in PTH
e. Finally (in late stage 4, early stage 5 disease), hyperphosphatemia and eventually hypocalcemia.
Most patients are also calcidiol (25-hydroxy vitamin D) deficient.
3. In stage 5 CKD, therapy is focused on maintaining the serum phosphate below 5.5 mg/dL by the use of adequate dialysis, dietary phosphate restriction, and phosphate binders.
4. Treatment of hyperparathyroidism in stage 5 CKD should be addressed with the use of vitamin D receptor activators (VDRAs) and calcimimetics.
5. The optimal PTH concentration in patients with stage 5 CKD has not been prospectively determined, and there are significant discrepancies between various PTH assays. Thus a reasonable approach is to manage patients with only one PTH assay, to follow trends in PTH levels (as suggested by K/DIGO), and to use appropriate clinical judgment in managing PTH levels. Kidney Disease: Improving Global Outcomes (K/DIGO) suggests a target of two to nine times the upper limit of normal for the particular PTH assay being used.
