Week 11 - Chronic Kidney Disease

Question 1

State important complications of chronic kidney disease.

Answer 1

1. Normocytic normochromic anaemia
2. Renal osteodystrophy
3. Peripheral neuropathy
4. Pruritus
5. Myoclonic jerking
6. Pericarditis

Question 2

Why does normochromic normocytic anaemia develop in CKD patients?

Answer 2

Relative deficiency of erythropoietin
Uraemia environment of CKD patients causes shortened red cell lifespan and inhibits bone marrow response to any endogenous erythropoietin

Question 3

What is the physiological basis for renal osteodystrophy in CKD patients?

Answer 3

Derangement in calcium and phosphate metabolism
Kidney responsible for excreting phosphate - phosphate accumulates, serum calcium is suppressed as a result - both these factors stimulate PTH release
PTH acts on bones and causes osteitis fibrosa cystica - secondary hyperparathyroidism
Kidney is responsible for the formation of active vitamin D - failure of hydroxylation occurs in CKD resulting in deficiency of 1, 25- dihydroxyvitamin D - reduced absorption of calcium from GI tract causing osteomalacia in bones

Question 4

Briefly describe the principles of peritoneal dialysis.

Answer 4

1. Peritoneal membrane is a semi permeable membrane
2. Dialysis fluid containing an osmotic agent allows water to be removed from patients membrane capillaries by osmosis
3. Solutes removed from patients capillaries by diffusion and convection into dialysis fluid

Question 5

Outline the principles of treatment for anaemia resulting from CKD.

Answer 5

Renal anaemia treated by administration of exogenous erythropoietin, of which there are a number of commercial preparations
Usually given by subcutaneous injections 1-3 times a week
Adequate iron stores are required for the patient to respond to erythropoietin, iron supplementation is frequently required and this can be administered through intravenous iron

Question 6

Outline the principles of bone disease caused by chronic kidney disease.

Answer 6

1. Measures aimed at reducing serum phosphate: dietary restriction and use of oral phosphate binders to reduce phosphate absorption from the gut
2. Number of products commercially available: some of which also contain a source of alimental calcium
3. Once phosphate is controlled, measures should be taken to ensure calcium is within acceptable range: potentially with the use of activated vitamin D supplements
4. PTH unacceptably high: despite these measures, surgical parathyroidectomy may be required.
5. Bisphosphonates - hyperparathyroidism
6. New class of drugs: calcium emetics - may be useful in suppressing PTH