Renal Flashcards
What 3 parts are the glomerular filtration barrier made up of?
- Epithelial cells of the bowmans capsule
- Glomerular basement membrane
- Fenestrated capillary endothelium
What forms the visceral layer of renal corpuscle in the glomerulus?
Podocytes
a) What is the glomerular filtration rate?
b) What methods are used to assess GFR?
a) The sun of the filtration rates in all the functioning nephrons - the volume of plasma filtered by the glomerulus per unit of time
b) - Creatine clearance - Plasma creating concentration - Estimation equation e.e.g Cockrofts Gault, MDRD
What is a healthy
a) GFR for women
b) GFR for men
c) Urine output
a) 95 +/- 20 ml/min
b) 120 +/- 25 ml/min
c) 2-3 L/day
What is creatine and where is it filtered?
Derived from metabolism of skeletal muscle and meat
Freely filtered across glomerulus and 15% from tubular secretion by proximal tubule
What is the formula for creatine clearance?
Urine creatine concentration x Volume / Plasma creatine concentration
What are the limitations of using creatine clearance?
- Incomplete urine collection
- Increased creatine secretion from tubule in renal impairment
If GFR is low, what will the level of creatine be?
What is the shape of the curve of creatine against GFR?
Creatine high
Exponential (L shape)
Who doesnt glomerular filtration rate work in?
- Children
- Amputees
- Pregnancy
Describe stage 1 and stage 2 of chronic kidney disease (CKD)
1 - GFR 90+, normal function, may have structural abnormalities, observe and control BP
2 - GFR 60-89, mildly reduced function, observe and control BP and address risk factors
Describe Stage 3 CKD
- GFR 30-59
- Pt asymptomatic
- Creatine marginally raised
- Tend to retain solutes, become hypertensive
- Reduced vit D and calcium
- Reduced Epo, become anaemic
- Observe, BP control and modify drug doses, avoid nephrotoxins
Describe Stage 4 CKD
- GFR 15-29
- Creatine 250-600umol/L
- Tired, pale, non-specifically unwell
- Need dietary restriction, phosphate binders, vit D and erythropoeitin
- Usually need anti-hypertensive drugs and diuretics
Describe Stage 5 CKD
- GFR <15
- Creatine >700
- End stage renal failure requiring dialysis if GFR<5mls/min or creatine >900
- Pale, tired, unwell
- Anorexic, nausea, vomiting, uraemic fetor, itch
- Confusion
- Fluid retention, oedema, congestive cardiac failure
What condition can cause chronic renal failure?
Diabetes (affects small blood vessels)
Give examples of drugs in CRF pts:
a) that are renally excreted so may accumulate
b) that have an altered protein binding
c) that are nephrotoxic so worsen renal function
a) Opiates
b) Increased protein binding = basic drugs e.g. lignocaine. Decreased protein binding = acidic drugs e.g. Phenytoin
c) NSAIDS, Gentamicin
What are the effects of uraemia on the haematology of CKF pts?
- Prolonged bleeding time
- Normal platelet count but disturbed platelet function
- Increased bruising
- Check pt not on aspirin or clopidogrel
How is bleeding time improved in CKF pt with uraemia?
Dialysis or increased haematocrit (with Erythropoeitin)
Name 4 effects of chronic renal failure
- Pulmonary and Peripheral oedema (due to salt and water retention)
- Restless Leg syndrome - cramps, tremors and twitches
- Hormonal imbalance
- Increased cardiac instability (severe metabolic acidosis, hyperkalaemia and hypocalcaemia)
What is the definition of acidaemia?
A pH of <7.2 (HCO3- <16mmol/L) that impacts cellular and cardiac function
What medical intervention can offer a bridge in pts with acidaemia until dialysis is available?
Sodium bicarbonate