renal osteodystrophy

Question 1

what is renal osteodystrophy?

Answer 1

a form of metabolic bone disease seen in patients with chronic renal insufficiency characterized by bone mineralization deficiency due to electrolyte and endocrine abnormalities. Patients present with osteomalacia, osteonecrosis and pathologic fractures.

Question 2

what are features of renal osteodystrophy?

Answer 2

Osteoporosis: ↓ bone density

Osteomalacia: ↓ mineralisation of osteoid (matrix)

secondary or tertiary hyperparathyroidism → osteitis fibrosa cystica
- Subperiosteal bone resorption
- Acral osteolysis: short stubby fingers
- Pepperpot skull

May get spinal osteosclerosis → Rugger Jersey spine
- Sclerotic vertebral end-plate w lucent centre

Question 3

what is the mechanism of renal osteodystrophy?

Answer 3

reduced 1α-hydroxylase → ↓ vit D activation → ↓ Ca → ↑ PTH

Phosphate retention → ↓ Ca and ↑ PTH (directly)

raised PTH → activation of osteoclasts ± osteoblasts

Also acidosis → bone resorption

Question 4

what is the managementn of renal osteodystrophy?

Answer 4

general- rx reversible causes, stop nephrotoxic rugs

lifestyle- exercise, healthy weight, stop smoking, na, fluid + PO4restriction

CV risk- statins, low dose aspirin, rx DM

HTN- target <140/90 or if DM <130.80, if diabetic nephropathy give ACEi/ARB even if normal BP

oedema- furosemide

bone disease
- phsophate binders- calcichew, sevelamer
- vit d analogues- alfacalcidol
- ca supplements
- ca mimetic- cinacalcet

anaemia
- exclude IDA + ACD
- EPO to raise hb to 110
higher would be a thrombosis risk

restless legs
- clonazepam