Chronic Kidney Disease

Question 1

Define chronic kidney disease (CKD) [1]

Answer 1

kidney damage or GFR<60ml/min/per 1.73m² for 3 months or more

Question 2

Serum Creatinine:

1. what is creatinine? [1]
2. how is it cleared from the kidneys? [2]
3. what is the relationship between serum creatinine and GFR? [1]
4. what are the problems with measuring serum creatinine only? [2]

Answer 2

1. creatinine is a product of muscle metabolism that is produced fairly constantly and has constant serum levels
2. freely filtered in the nephron but there is slight tubular secretion at the collecting ducts
3. serum creatinine is inversely proportional to GFR
4. problems with serum creatinine:
   
   • exponential relationship leads to:
     
     • slow recognition of the loss of first 70% of renal function (lag time) and then sudden risk in creatinine with late renal referral
   • effect of muscle mass leads to:
     
     • overestimation of function in women, elderly and other low muscle mass groups (e.g. rheumatoid/amputees etc.)

Question 3

Describe the NKF classification of CKD [6]

Answer 3

• Stage 1
  
  • eGFR > 90
  • normal or increased eGFR, with other evidence of kidney damage such as proteinuria/pyleonephritis etc.
• Stage 2
  
  • eGFR: 60-89
  • slight decrease in eGFR, with other evidence of kidney damage
• Stage 3a
  
  • eGFR: 45-59
  • mild-moderate decrease in eGFR
• Stage 3b
  
  • eGFR: 30-44
  • moderate-severe decrease in eGFR
• Stage 4
  
  • eGFR: 15-29
  • severe decrease in eGFR
• Stage 5
  
  • eGFR <15
  • established renal failure

Question 4

What are the causes of chronic kidney disease? [7]

Answer 4

1. diabetic nephropathy
2. renovascular disease/ischaemic nephropathy
3. membranous glomerulonephritis
4. IgA nephropathy
5. reflux nephropathy/chronic pyelonephritis
6. autosomal dominant polycystic kidney disease (ADPKD)
7. obstructive uropathy

Question 5

What are the signs [7] and symptoms [9] of advanced CKD?

Answer 5

• symptoms:
  
  • pruritus
  • nausea
  • anorexia/weight loss
  • fatigue
  • leg swelling
  • breathlessness
  • nocturia
  • joint/bone pain
  • confusion
• signs:
  
  • peripheral and pulmonary oedema
  • pericardial rub
  • rash/excoriation
  • hypertension
  • tachypnoea
  • cachexia
  • pallor and/or lemon yellow tinge

Question 6

What management measures are used to slow progression of CKD? [6]

Answer 6

1. aggressive BP control → ACE inhibitors/ARB
2. good diabetic control
3. diet
4. smoking cessation
5. lowering cholesterol
6. treat acidosis

Question 7

What are the main complications of CKD that need to be taken into account in the treatment strategy? [4]

Answer 7

1. anaemia
2. acidosis
3. oedema
4. CKD bone-mineral disorders (MBD)

Question 8

Anaemia in CKD

1. at what eGFR level does anaemia commonly develop? [1]
2. initial treatment? [3]
3. treatment? [1]
4. what should be the trigger to investigating possible CKD anaemia? [1]

Answer 8

1. common when eGFR <30
2. replace iron, B12, folate first if low
3. erythropoietin stimulating agents (ESA), e.g. Darbepoietin every 2 weeks
4. trigger usually Hb <100g/l

Question 9

How do you treat CKD bone mineral disorders (CKD-MBD)? [4]

Answer 9

1. activated vitamin D
2. occassionally Mg supplements
3. phosphate binders
   
   • calcium based → calcium carbonate/acetate
   • non-calcium based → sevelamer/aluminium
4. parathyroidectomy

Question 10

When should you start dialysis? [9]

Answer 10

1. Individual approach based on symptoms
2. Most start with eGFR 6-8ml/min
3. If there is:
   
   • weight loss and persistent nausea
   • peristent hyperkalaemia
   • acidosis
   • severe hyper-phosphataemia
   • pruritis (itchy skin)
   • problematic fluid overload