Clinical Renal failure and tests

Question 1

Blood tests for kidney failure

Answer 1

Creatinine and urea

Urea: higher when high protein intake; higher protein catobolism in infection; GI bleeding
Some is reabsorbed i.e is higher in dehydration

Creatinine: is proportional to muscle mass. Is NOT reabsorbed, so creatinine clearance is proportional to GFR

Question 2

Things about creatinine

Answer 2

After a meal of meat, creatinine will rise, and will falsely signify low GFR

Question 3

What will affect eGFR (better than just creatinine)

Answer 3

Weight (muscle)
Age
Gender
creatinine

Question 4

What are eGFR limitations?

Answer 4

• Only useful if muscle mass is normal

- In steady state, not useful in acute kidney problems

Question 5

Acute kidney injury types

note it is sudden decline in GFR and usually reversible

Answer 5

Non renal 70% of cases

Pre renal; renal; post renal

Question 6

Pre renal AKI

Can get better or can get acute tubular necrosis

Answer 6

Causes are low BP; dehydration; sepsis; haemorrhage; cardiogenic shock; RA stenosis

Urine output is lower and will have high creatinine, hyperkalaemic (???)
high phophate and low calcium maybe

treatment (fix underlying problem)- rehydrate, treat bleeding, antibiotics, heart fixing

Question 7

Renal injury AKI

Answer 7

Acute tubular necrosis (80%)
mainly due to pre renal (low BP)
Also may be drugs (heroin, crack, contrasts) and toxins
OR rapid progressive glomerulonephritis

takes a while to heal, may need dialysis (NB dialysis does not heal the kidneys! keeps you alive by preventing hyperkalaemia)
maintain BP

Recovery- 95% get better; need IV fluids, as due to tubule damage can not concentrate urine so loads of urine

Question 8

RPGN

Answer 8

presents with blood or protein in urine and needs biopsy to diagnose

Question 9

Post renal AKI

Answer 9

Kidney stones, tumours, BPH, urinary retention

Question 10

CKD

Answer 10

Gradual decline in GFR and happens over years
Caused by: diabetes; glomerulonephritis, hypertension and more
glomerular scarring and slowly elevating creatinine

Question 11

What can uraemia cause? (note urea in blood as a result of reduced GFR)

Answer 11

Anorexia, nausea, vomiting, itchiness, SOB etc

Question 12

What are some other useful blood tests?

Answer 12

haemoglobin (due to low erythopoietin); increased serum phosphate; less active vitamin D (calcitriol) causing less calcium absorption in gut –> hyper parathyroidism

Question 13

How is bone affected/

Answer 13

Due to low calcium, and high phosphate in blood (low calcitriol also), high PTH meaning bone resoprtion. e bad. so fractures and extra osseus (like vascular) calcification