Chronic Kidney Disease

Question 1

What is normal GFR levels?

Answer 1

Normal GFR is 90-120ml/min

Question 2

What is the minimum number of nephrons we can survive on and what is this as a percentage of our normal amount.

Answer 2

2 x 10^6 nephrons normally.

Only 40’000 sufficient to survive (2%)

Question 3

What is chronic kidney disease?

Answer 3

Chronic kidney disease is a disease of structure or function that may have no symptoms.

Question 4

What is the aetiology (causes) of CKD

Answer 4

• Idiopathic
• Immunologic – glomerulonephritis,
• Infection – pyelonephritis
• Genetic – PCK, Alport’s
• Obstruction and reflux nephropathy
• Hypertension
• Vascular
• Systemic disease – diabetes, myeloma

Question 5

What are the most common co-morbidities that a CKD patient would present with?

Answer 5

Most patients with CKD will have diabetes, hypertension, or ischaemic heart disease

Question 6

Who is CKD more common in?

Answer 6

More common in elderly, multi-morbid, ethnic minorities and socially disadvantaged.

Question 7

How do we classify CKD?

Answer 7

This has two staging parts the first is based on GFR (or rather eGFR) and has 6 stages G1 to G6 with G3a and G3b the second is based on their urine albumin creatinine ratio (the higher it is the worse it is) which has 3 ratings from A1 to A3. You then define them as (for example CKD G4A1)

Question 8

How can you be a CKD G1?

Answer 8

Also have proteinuria or haematuria.

Question 9

What rate is the GFR/eGFR readings from creatinine not accurate above?

Answer 9

60ml/min

Question 10

What percentage of the population have CKD 3 or worse?

Answer 10

7% of the population

Question 11

What is the biggest killer in people with CKD?

Answer 11

Cardiovascular diseases

Question 12

How does CKD progress over time in very general terms?

Answer 12

In a lot of patients CKD slowly worsens with progressive loss of renal function

Question 13

Why is it important to catch people who have CKD early?

Answer 13

Some people deteriorate at slightly different rates and may never actually present with symptoms. If those of us who’s renal function were to be on a high rate of deterioration are caught early this can dramatically change their lives in the future.

Question 14

Whats the difference in effectivity between dialysis and transplants?

Answer 14

Dialysis not as effective as the real thing i.e. a transplanted kidney. If you are on dialysis you are much more likely to die in the near future than if you have a transplant.

Question 15

At what eGFR does the risk of death begin to rapidily increase?

Answer 15

75ml/min

Question 16

When should people be tested for CKD?

Answer 16

If they have protein or blood in urine and if they are hypertensive then you should test people for CKD.

Question 17

How does proteinuria effect prognosis?

Answer 17

If you have protein in your urine this gives you a much worse prognosis that someone in the same CKD stage as you without protein in their urine.

Question 18

Why can’t we use raw serum creatinine values to calculate GFR?

Answer 18

Non-Linear relationship between GFR and creatinine so not a very good measurement. Especially when GFR is going past 60ml/min. Also there is a large variation between body build, sex, age, race and nutrition.

Question 19

What is eGFR?

Answer 19

eGFR still uses the relationship between creatinine and GFR as before but accounts for age, sex and origin. Only accurate in adults, correction for black patients and only valid for CKD not in AKI.

Question 20

How do we measure the gold standard GFR?

Answer 20

Can measure GFR but it’s hard and time consuming: Inulin clearance, Cr51 EDTA clearance Iohexol clearance or creatinine clearance (24 hour urine).

Question 21

What iamging techniques can we use in CKD and what would we look for?

Answer 21

Imaging of Kidneys
USS – size, hydronephrosis (distension and dilation of the renal pelvis) and CT/MRI scans looking again at general anatomy, hydronephrosis and also vasculature issues.

Question 22

What’s special about CKD in polycystic kidney disease?

Answer 22

Polycystic kidney disease – have CKD from day one but renal function not compromised until around 50.

Question 23

When is a renal biopsy done?

Answer 23

If kidneys are normal size and the cause of CKD is not obvious a renal biopsy could be considered.

Question 24

Describe the 3 most common chronic complciations of CKD?

Answer 24

Acidosis
Affects muscle, bone and renal function progression. Treated with oral sodium bicarbonate tablets. This doesn’t tend to occur until eGFR is < 25.

Anaemia
Decreased erythropoietin production, also resistance to erythropoietin due to the uraemic environment which also causes decreased RBC survival.

Mineral and bone disorders
Uraemic environment – if GFR decreases phosphate increases. When GFR is low active Vit D decreases so calcium decreases. As a result of both of these PTH increases. The low Vit D causes Osteomalacia and the increase PTH causes osteitis Fibrosa cystica (excess bone break down causing inflammation and weak bones due to osteoclast overactivity).

Question 25

How will the mineral and bone disorders associated with CKD present?

Answer 25

Rugger jersey spine and erosion to terminal phalanges and bone cysts are common. Also causes non bone calcification in joints, arteries and peripheral vessels (Calciphylaxis).

Question 26

How can we prevent progression of CKD?

Answer 26

Lifestyle – smoking, obesity and lack of exercise
Treat diabetes 
Treat high blood pressure
ACE inhibitors/ARBs in proteinuria
Lipid lowering

Question 27

When does renal replacement therapy become needed?

Answer 27

Renal replacement therapy – required when native renal function declines to a level no Longer adequate to support health. Usually when eGFR 8-10 ML/MIN.

Indication of initiation of Dialysis
Uraemic symptoms – acidosis, pericarditis, fluid overload and hyperkalaemia.