Renal

Question 1

What are the functions of the kidneys?

Answer 1

Excretion/Homeostasis (Disturbed early in AKI and late in CKD)

• Waste products of metabolism
• Fluid/electrolyte balance
• Acid/Base balance
• Removal of drugs & toxins

Endocrine (disturbed in CKD)

• RAAS
• EPO production
• Hyroxylation of vitamin D

Question 2

What is an AKI, its stages and how is it measured?

Answer 2

Stages 1, 2, 3

Measure via creatinine and urine output

Question 3

What is normal urine output?

Answer 3

0.5ml/kg/hr

Question 4

Pre-renal causes of AKI?

Answer 4

Under-perfusion

-Hypovolaemia (haemorrhage, dehydration), sepsis, renal artery stenosis, HF

Question 5

Intra renal causes of AKI?

Answer 5

Ischaemia, nephrotoxins, infection, trauma

Question 6

Post-renal causes of AKI?

Answer 6

Stones tumour, prostatic hypertrophy

Question 7

Is urea higher or lower compared to creatinine in pre-renal failure?

Answer 7

Urea is much higher

Question 8

What is urine sodium concentration like in pre-renal and intrinsic kidney damage?

Answer 8

Urine sodium conc is low in pre-renal as there is under-perfusion of the kidney and aldosterone is switched on which causes salt retention

In intrinsic kidney damage you cant reabsorb salt so loads of urine with electrolytes including sodium are excreted

Question 9

Why is is important to know whether its pre-renal or intrinsic kidney damage with regards to giving fluids?

Answer 9

In a pre-renal under-perfusion cause giving fluids is what the kidneys need. In intrinsic damage, giving more fluids can cause fluid overload, so need to be able to distinguish between them.

Question 10

What is disturbed first in AKI, excretion/homeostasis or endocrine functions?

Answer 10

AKI excretion/homeostasis first

CKD endocrine functions

Question 11

What are the clinical features of intrinsic AKI?

Answer 11

Non-specific and late
Nausea weight loss, itchy skin symptoms
High K+
-retaining K - life-threatening >8
Acidosis
-retaining acidic waste, life threatening if pH <7
Retaining nitrogenous waste - nausea, malaise, confusion
Retain salt and water - reduced GFR
Get hyponatraemia
These result from a failure to remove nitrogenous waste products, fluids, electrolytes, acids
No endocrine problems in AKI

Question 12

What is the stepwise management for an AKI?

Answer 12

Distinguish cause as pre, intra or post renal

Ask for senior review/refer to AKI team

Stop/avoid ACEi/ARBs, NSAIDS and other nephrotoxic medications

Correct life-threatening fluid, electrolyte and acid/base abnormalities

Restoral renal perfusion if pre-renal

Support renal function in life-threatening intrinsic AKI - haemofiltration, dialysis

Question 13

What is CKD?

Answer 13

Gradual irreversible change in renal function

Question 14

What are causes of CKD?

Answer 14

Diabetes, HTN, polycystic kidney disease, recurrent pyelonephritis, interstitial nephritis, multisystem disease, drugs

Question 15

What does eGFR use to calculate the score?

Answer 15

Age, sex, plasma creatinine.

Correct for ethnicity and pediatrics.

Question 16

What is creatinine influenced by?

Answer 16

Gender, ethnicity, age, body mass, diet, exercise

Question 17

What is creatinine?

Answer 17

A metabolic product of the body excreted by the kidneys

Question 18

When is it best to use eGFR and when creatinine to measure kidney function?

Answer 18

Creatinine - better at showing extremes - AKI

eGFR - good for stable disease - CKD

Question 19

What is used to monitor CKD?

Answer 19

For early CKD - eGFR

In the later stages you use creatinine as that changes more than eGFR

Question 20

What is the relationship change in eGFR and creatinine

Answer 20

GFR typically reduced by 50% before serum creatinine is increased

Question 21

How many stages to CKD?

Answer 21

1 - >90
2 - 60-90
3a - 45-60
3b - 30-44
4 - 15-30
5 <15
eGFR

Question 22

Biochemical changes in CKD stages 3-4

Answer 22

Elevated creatinine, reduced eGFR
Endocrine changes:
hypocalcaemia, secondary hyperparathyroidism, reduced EPO - causes anaemia, elevated cholesterol and triglycerides
Impaired immune function

Question 23

Biochemical changes in CKD stages 4-5

Answer 23

Elevated creatinine and urea, high phosphate, acidosis, hyperkalaemia