Chronic kidney disease: mineral and bone disease (CKD-MBD)
The definition of CKD-MBD is: a systemic disorder of mineral and bone metabolism due to CKD manifested by either one or a combination of the following:
- Abnormalities of calcium, phosphorus, PTH, or vitamin D metabolism
- Abnormalities in bone turnover, mineralization, volume, linear growth, or strength
- Vascular or other soft tissue calcification
The term renal osteodystrophy (ROD) should be used exclusively to describe the alterations in bone morphology that occur in patients with CKD based on histological examination of bone biopsy.
CKD-MBD has the following characteristics:
- hyperphosphatemia due to decreased renal excretion and decrease bone buffering
- vitamin D deficiency due to calcidiol deficiency (elderly, diabetes, proteinuria) and the inability to synthesize calcitriol in the kidneys
- hypocalcemia and secondary hyperparathyroidism
- vascular calcification of intima or media which may accelerate athero- and arteriosclerosis
This pathophysiology results in symptoms such as spontaneous fractures, pain in the bones, malformations and contributes to cardiovascular disease, ie. heart failure and sudden death.
Treatment aims at prevention of complications due to CKD-MBD. Control of the phosphate levels by dietary phosphate restriction and phosphate binders like calcium carbonate or calcium acetate is essential in this respect. If this is not sufficient, sevelamer or lanthanum carbonate could be used. Cholecalciferol (early CKD), alfacalcidol or paricalcitol (in hemodialysis patients) can be given in order to treat vitamin D deficiency and thereby control PTH secretion.
What is NOT a complication of severe hypophosphatemia?
Extra info: Increased CPK is due to muscle fiber necrosis and even rhabdomyolysis. Respiratory muscle weakness is usually seen as difficult weaning from a ventilator in the ICU setting. Hypocaliuria is the correct answer, because it is HYPERcalciuria and HYPERmagnisuria. Cardiac dysrrhythmias usually resistant to antiarrhythmics.
Renal osteodystrophy is a form of: