2155 (IC13) CKD

Question 1

Ideal substance for GFR estimation (5 points)

Answer 1

Freely filtered, not reabsorbed, not secreted, not metabolised, not synthesised

Question 2

Disadvantages of urea clearance

Answer 2

1. reabsorbed at renal tubules
2. extent of reabsorption varies during dehydration vs diuresis
3. urinary excretion proportional to urine flow rate

Question 3

Normal values of Serum Creatinine in Males and Females

Answer 3

100umol/L in Males
80umol/L in Females

Question 4

Limitations of using Serum Creatinine

Answer 4

1) Synthesis of creatine is affected by people with impaired liver function or critically ill

2) Production of Creatinine not constant
Proportional to lean body weight/muscle mass
Affected by ingestion of cooked meat

3) Secreted in proximal tubules
More SCr secretion in low GFR, glomerular renal diseases → overestimation of GFR in advanced CKD patients
More secretion when taking drugs eg. trimethoprim, cimetidine
Non renal excretion of Cr by gut metabolism

4) Unstable renal function
SCr needs time to reach steady state, hence wont reflect AKI in its early stage

5) Interference of Cr assays
Lead to falsely elevated results

Question 5

Cockroft and Gault Equation

Answer 5

(140-age) x weight x 0.85 If female / 72 x SCr in umol/L / 88.4

Question 6

What labs are increased in CKD?

Answer 6

SCr, urea, K, P, PTH, BP, glucose, lipids, Ca (if on vitamin D therapy)

Question 7

What labs are decreased in CKD?

Answer 7

GFR, CrCl, CO2 (metabolic acidosis), Hgb(anemia), iron stores (Fe deficiency), 25(OH)D (vit D deficiency), albumin (malnutrition), glucose, Ca (early stages of CKD), HDL

Question 8

BP Goal for CKD (SBP) based on 2021 KDIGO guidelines

Answer 8

less than 120 SBP

Question 9

Synergistic effect of ACE/ARB and diuretics (2 points)

Answer 9

1) Diuretics decrease ECF vol, resulting in reflex activation of RAAS. Hence ACE/ARB can counter this reflex activation of RAAS

2) Diuretics cause excretion of Na and K, help counter hyperkalemia SE that ACE/ARB may cause.

Question 10

When to stop ACEi/ARB in CKD?

Answer 10

1) SCr increases by more than 30%
2) K+ > 5.5mmol/L (and check for diet)

Question 11

How do CKD patients with nephrotic syndrome (>3.5g protein in urine) get hyperlipidemia?

Answer 11

Liver senses the loss of proteins in urine, will increase lipoproteins to counter this and cause LDL to increase

Question 12

Do we treat LDL level in CKD? Why?

Answer 12

No, just fire and forget. There is no relationship between LDL and CKD mortality risk.

Question 13

What to do with high TG in CKD patients

Answer 13

Increase dose of statins to decrease TG, only start Gemfibrozil (fibrates) when TG > 11.3

Question 14

DDI of statins

Answer 14

Macrolides eg. Clarithromycin (in H.pylori)
Hold off statin until antibiotic course is complete
Colchicine
Amplodipine (w Simvastatin)
Grapefruit juice

Question 15

Recommended water intake for CKD pts

Answer 15

1-1.5L a day, 800ml-1L for dialysis

Question 16

Salt intake for CKD

Answer 16

5g of salt aka 1 teaspoon

Question 17

Why do CKD patients experience hypernatremia?

Answer 17

Cannot adjust to sudden increase of salt intake

Question 18

How does metabolic acidosis occur?

Answer 18

In CKD, there is decreased H+ excretion , causing pH and serum bicarb to fall

Patient’s bone detect increase in acidity and breaks down bone, releasing CaCO3

Question 19

Why does malnutrition occur in CKD? (4 pts)

Answer 19

Poor dietary intake due to anorexia, altered taste, limited food choices, depression, gastroparesis (gastric emptying rate slowed down → feel full quickly)

Loss of nutrients eg. glucose, vitamins from dialysis

Hypercatabolism (Breakdown of fat and muscle) from inadequate caloric intake

Blood loss from dialysis

Question 20

What are examples of vitamins and proteins supplements?

Answer 20

Renal vit
Nepro HP or LP
Valens

Question 21

What does HBA1C measure?

Answer 21

HBA1C is measure of amount of glucose attached to haemoglobin in past 3 months

Question 22

What is the range of HBA1C in CKD patients?

Answer 22

6.5-8%

Question 23

Who should have tighter or looser control of HBA1C?

Answer 23

Tighter control ~ 6.5%
For mild CKD G1, few comorbidities, Long life expectancy, lower risk of hypoglycaemia

Less tight control ~ 8%
For severe CKD eg. G5, more comorbidities, short life expectancy, higher risk of hypoglycaemia

Question 24

eGFR cut off for metformin

Answer 24

> 30

Question 25

eGFR cut off for SGLT2i

Answer 25

> 20

Question 26

When to discontinue metformin and what could it cause?

Answer 26

when GFR < 30, may cause lactic acidosis

Question 27

Why does diabetes control seem to be better in CKD patients?

Answer 27

Cos of decreased kidney function → accumulate insulin and diabetic medications in body → Increase risk of hypoglycaemia

Patients still have diabetes, just have to lower dose of diabetes medications