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Renal Osteodystrophy

Constellation of musculoskeletal abnormalities occurring with chronic renal failure featuring some combination of

o    Osteomalacia (adults)

o    Rickets (children)

o    2° hyperparathyroidism

o    Soft-tissue calcifications

o    Osteosclerosis

o    Soft-tissue + vascular calcifications

·     Low calcium levels lead to osteomalacia

o    Additional factors responsible for osteomalacia are

§     Inhibitors to calcification produced in the uremic state

§    Aluminum toxicity

§    Dysfunction of hepatic enzyme system A

§    Renal insufficiency with diminished filtration results in phosphate retention

·    Maintenance of Ca x P product lowers serum calcium directly, which in turn increases parathyroid hormone production (2°hyperparathyroidism)

·   Osteopenia

o    Combined effect of

§    Osteomalacia (reduced bone mineralization due to acquired insensitivity to vitamin D / antivitamin D factor)

§    Osteitis fibrosa cystica (bone resorption)

§    Osteoporosis (decrease in bone quantity)

o    Complications

§    Fracture predisposition (lessened structural strength) with minor trauma

·   Spontaneously

§    Fracture prevalence increases with duration of hemodialysis + remains unchanged after renal transplantation

·   Sites of fractures

o   Vertebral body (3-25%)

o   Pubic ramus, rib (5-25%)

o   Milkman fracture / Looser zones (in 1%)

o   Metaphyseal fractures

o   Prognosis

§    Osteopenia may remain unchanged / worsen after renal transplantation + during hemodialysis

·   Secondary hyperparathyroidism

o    Cause

§    Inability of kidneys to adequately excrete phosphate leads to hyperplasia of parathyroid chief cells (2° hyperparathyroidism)

§     Excess parathyroid hormone affects the development of osteoclasts, osteoblasts, osteocytes

o    Hyperphosphatemia

o    Hypocalcemia

o    Increased PTH levels

o    Subperiosteal, cortical, subchondral, trabecular, endosteal, subligamentous bone resorption

o    Osteoclastoma = brown tumor = osteitis fibrosa cystica (due to parathyroid hormone -stimulated osteoclastic activity

§   More common in 1° hyperparathyroidism

o    Periosteal new-bone formation (8-25%)

o    Chondrocalcinosis

§    More common in 1° hyperparathyroidism)

·   Osteosclerosis (9-34%)

o    One of the most common radiologic manifestations

§    Most common with chronic glomerulonephritis

o    May be the sole manifestation of renal osteodystrophy

o    Diffuse chalky density

o   Thoracolumbar spine in 60% with dense end-plates produce appearance of rugger-jersey (rugger jersey spine)


rugger jersey spine

 Rugger-jersey spine in
Renal osteodystrophy

o      Also in pelvis, ribs, long bones, facial bones, base of skull (children)

o    Prognosis

§   May increase/regress after renal transplantation

·  Soft-tissue calcifications

o   Metastatic secondary to hyperphosphatemia (solubility product for calcium + phosphate exceeds 60-75 mg/dL in extracellular fluid)

§   Hypercalcemia

§   Alkalosis with precipitation of calcium salts

o  Dystrophic secondary to local tissue injury

§   Location

·   Arterial (27-83%)

o   In medial + intimal elastic tissue

§   Dorsalis pedis a., forearm, hand, wrist, leg

o   Pipestem appearance without prominent luminal involvement

·        Periarticular (0-52%)

o   Multifocal

o   Frequently symmetric

o   May extend into adjacent joint

o  Chalky fluid / pastelike material

o  Inflammatory response in surrounding tenosynovial tissue

o  Discrete cloudlike dense areas

§  Fluid-fluid level in tumoral calcinosis

o       Prognosis

§  Often regresses with treatment

· Treatment

o   Decrease of phosphorus absorption in bowel

o   Vitamin D3 administration (if vitamin D resistance predominates)

o   Parathyroidectomy for 3° hyperparathyroidism (= autonomous hyperparathyroidism)