pathophysiology of CKD Flashcards
(27 cards)
What is CKD?
decrease in GFR which occurs over months or years and is usually irreversible
How is CKD classified?
1) 90+ (eGFR)
2) 60-89
3) 30-59 (CKD)
4) 15-29 (CKD)
5) <15 (CKD)
What are the symptoms of abnormal kidney function?
- Symptoms often present very late into disease
- Fatigue caused by anaemia
- Breathlessness due to metabolic acidosis and fluid retention
- Leg swelling due to fluid retention
- Nausea due to toxin retention
- Itch due to retained toxins
- bone pain due to Vitamin D deficiency
Why does CKD cause anaemia?
- oxygen sensing apparatus doesn’t work properly
- less ertythropoetin generated by the kidneys and so less stimulus to bone marrow and red cell mass falls
- causing anaemia (normochromic and normocytic)
What are the signs of abnormal kidney function?
- Pallor (anaemia)
- pitting oedema (salt and fluid retention)
- Hypertension (linked to salt and fluid retention)
- Proteinuria or haematuria (blood)
What are the main causes of CKD?
1) diabetic kidney disease
2) Hypertensive and or atherosclerotic vascular disease of kidneys
3) Glomerulonephritis
4) polycystic kidney disease
5) Tubulointerstitial disease
What are the risk factors for CKD?
- diabetes
- hypertension
- smoking
- dyslipidemia
- age
- male
- genetics
- cardiac disease (renal can also cause cardiac)
What will histology of diabetic glomerulus show?
- mesangial cell expansion
- expansion of extracellular matrix around cell
How does diabetes cause kidney disease?
Neuropathy in diabetics can cause development of nodules on the glomeruli this decreases the number of capillaries available for BF so GFR falls
What is the pathology of diabetic nephropathy?
- rise in intraglomerular hypertension which causes glomerular scarring
- high blood glucose causes mesangial expansion and damage to basement membrane (causes thickening)
What is the problem with a thickened basement membrane?
- basement membrane starts leaking so allows albumin to get into urine
- increases pressure in the glomeruli causing damage
What is the problem with albumin in urine?
Proteinuria is toxic to tubules
What is the result of progressive diabetic kidney disease?
- Tubular atrophy
- Fibrosis
- cellular infiltrate
- vasculopathy
Why do ACE inhibitors help with CKD?
- ACE inhibitors and ARB are used to treat proteinuric renal disease
- block Ang II formation so allow efferent arteriole to vasodilate and reduce glomerular pressure
What are the consequences of a reduced GFR?
Fluid retention: - Heart failure - tissue oedema reduced metabolite excretion - uraemia - increased serum creatine - increased serum urate (can cause gout) - increased drug levels due to prolonged T1/2
What are the two key issues with drug prescribing in renal disease?
1) kidney failure prolongs T1/2 of many drugs leading to increased toxicity
2) some drugs make kidney failure worse by disturbing BF to kidney e.g. NSAIDS
Consequences of reduced renal tubular failure?
reduced fluid reabsorption - polyuria - nocturia Reduced K+ excretion - hyperkalaemia reduced acid secretion and reduced bicarbonate formation - metabolic acidosis
Renal bone disease pathology?
- reduced Vit D activation due to kidney damage
- decreased calcium absorption
- decreased mineralisation of bone (osteomalacia)
- reduced Levels of vitamin D and low calcium levels stimulate release of parathyroid hormone resulting in bone resorption
What ion levels will increase in response to calcium?
phosphate
How does calcium and phosphate levels impact Vit D production?
Low calcium = high phosphate = low Vit D production
High calcium = low phosphate = high vit D production
What hormone is released as a result of low calcium and high Vit D
- Parathyroid hormone which will Bring up levels of calcium
- can get ectopic calcification of soft tissues
How is CKD managed?
- treat hypertension
- slow progression of proteinuric renal disease using ACEi or ARB
- reduce associated CV risks e.g. statins for hyperlipideamia
- treat complications e.g. anaemia (Epo injections), renal bone disease (activated Vit D), hyperphosphataemia (phosphate binding drugs) and hyperkalaemia (restrict dietary intake)
Renal replacement therapies for End-stage Renal disease?
Haemodialysis - vascular access e.g. arteriovenous fistula or central venous catheter
Peritoneal dialysis - catheter inserted into abdomen with incision below umbilicus to insert and exit site on right to left side of lower abdomen
Kidney transplant - placed in the left or right iliac fossa (palpable kidney underneath a surgical scar)
What is the differences between hameodialysis and peritoneal dialysis?
H: - hospital based - nurse delivered - 3x week - need access to blood - very expensive - restricted to sites with dialysis machines P: - Home-based - patient performs dialysis - daily - uses abdominal cavity - cheaper - can be done virtually anywhere
