Renal Biochemistry - AKI

Question 1

What are the main roles of the kidneys? (6)

Answer 1

Water, electrolyte + BP (RAAS) regulator.
Glucose, protein retention.
Maintain acid/base balance.
Excretes waste products (urea, creatinine), water soluble substances and medicines.
Endocrine functions (epoetin, activating vitamin D)
CO for perfusion.

Question 2

What is the Cockcroft-Gault equation? (1)

Answer 2

(140-Age) x weight (kg) x constant
Serum creatinine (umol/L)

Constant: F = 1.04, M = 1.23

Question 3

Define AKI. (1)

Answer 3

Acute Kidney Injury:
- Rapid deterioration in renal function over hrs or days = creatinine > eGFR.

Question 4

Explain the SCr criteria for stage 1 AKI. (2)

Answer 4

Increase >= 26umol/L within 48 hrs OR

Increase >= 1.5-1.9 x ref. SCr.

Question 5

Explain the urine output criteria for stage 1 AKI. (1)

Answer 5

<0.5ml/kg/hr for > 6 consecutive hrs.

Question 6

Explain the SCr criteria for stage 2 AKI. (1)

Answer 6

Increase >=2-2.9 x reference SCr.

Question 7

Explain the urine output criteria for stage 2 AKI. (1)

Answer 7

< 0.5ml/kg/hr for > 12 hrs.

Question 8

Explain the SCr criteria for stage 3 AKI. (3)

Answer 8

Increase >= 3 x ref. SCr OR
Increase >= 354umol/L OR
Commenced on renal replacement therapy (RRT) irrespective of stage.

Question 9

Explain the urine output criteria for stage 3 AKI. (2)

Answer 9

< 0.3ml/kg/hr for > 24 hrs OR
Anuria for 12 hrs.

Question 10

What must be obtained for interpreting SCr levels? (1)

Answer 10

Patient’s baseline.

Question 11

What are the consequences of AKI? (4)

Answer 11

High morbidity + mortality.
Small rise in SCr = poorer outcomes.
Increased hospital admissions and length of stay.
Patients may need LT RRT.

Question 12

What are the pre-renal causes of AKI? (3)

Answer 12

1. Reduced perfusion:
   - Hypovolaemia,
   - Dehydration,
   - Burns,
   - Cardiac/vascular disease,
   - Reduced CO,
   - Low BP.
2. Sepsis/infection
3. Haemorrhage.

Question 13

What are the intrinsic causes of AKI? (4)

Answer 13

Kidney disease
Vasculitis
Necrosis
Rhabdomyolysis

Question 14

What are the post-renal causes of AKI? (3)

Answer 14

Fluid retention,
Renal stones obstruction
Prostate CA.

Question 15

What are the risk factors of AKI? (7)

Answer 15

Advanced Age
Sepsis, Hypovolaemia, Hypotension (Fluids, infection identification and management)
Diabetes
HF
Liver Disease
Atherosclerotic PVD
CKD, Hx of AKI (monitor renal function)
Surgery
Medication, use of contrast media (avoid nephrotoxic)
Low albumin (treat)

Question 16

Give e.g. of nephrotoxic medications that should be avoided in AKI. (5)

Answer 16

Contrast Media
DAMN drugs:
- Diuretics
- ACEi/ARBs
- Metformin
- NSAIDs

Question 17

What are the monitoring requirements when using medicines in AKI patients? (2)

Answer 17

Renal function
Electrolytes (U+E’s)

Question 18

What renal condition would you consider dose adjustments? (1)

Answer 18

CKD

Question 19

What are the sick day rules that apply with AKI? (2)

Answer 19

Withhold DAMN drugs
SGLT2i (not nephrotoxic but dangerous in low CrCl)