Renal osteodystrophy

Renal osteodystrophy is a bone pathology, characterized by defective mineralization, that results from renal disease. renal - refers to kidney, osteo - refers to bone, and dystrophy - means degenerative disorder (like dystrophy in muscular dystrophy). more...

There are a different forms of renal osteodystrophy. Renal osteodystrophy that is charachterized by high bone turnovver and renal osteodystrophy that is charachterozed by low bone turover

Signs and symptoms

• Silent (no symptoms).
• Bone pain.
• Joint pain.
• Bone deformation.
• Fractures.

Diagnosis

Usually diagnosed after treatment for end-stage renal disease (ESRD) begins.

• Blood tests - calcium (is decreased), phosphate (is elevated), calcitriol (vitamin D) (is decreased), PTH (is elevated).
• Bone biopsy (bone has abnormal structure).

Can be recognized on X-ray (but may be difficult to differentiate from other conditions). Features on X-ray:

• Calcification of cartilage (chondrocalcinosis) - typically at the knees and pubic symphysis.
• Bone loss - "patchy" appearance (osteopenia)
• Fractures

Pathogenesis

Renal osteodystrophy results from an abnormally elevated serum phosphate (hyperphosphatemia) and low serum calcium (hypocalcemia), both of which are due to decreased excretion/no excretion of phosphate by the damaged kidney, low vitamin D levels and/or tertiary hyperparathyroidism (a dysfunction of the parathyroid gland due to constant stimulation).

Differential diagnosis

• osteoporosis
• osteopenia
• osteomalacia
• hyperparathyroidism
• multiple myeloma
• soft tissue calcification including collagen-vascular disease
• hydroxyapatite crystal deposition disease
• hypervitaminosis

Treatment

• calcium supplementation
• dietary phosphate restriction
• vitamin D
• phosphate binders calcium carbonate (Tums), calcium acetate (PhosLo), sevelamer hydrochloride (Renagel), or lanthanum carbonate (Fosrenol)
• cinacalcet - a calcimimetic
• frequent hemodialysis (five times a week) is thought to be of benefit.
• renal transplantation

Prognosis

Recovery from renal osteodystrophy has been observed post renal transplantation. Renal osteodystrophy is a chronic (persistent) condition with a conventional hemodialysis schedule.

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