pathophysiology of CKD

Question 1

What is CKD?

Answer 1

decrease in GFR which occurs over months or years and is usually irreversible

Question 2

How is CKD classified?

Answer 2

1) 90+ (eGFR)
2) 60-89
3) 30-59 (CKD)
4) 15-29 (CKD)
5) <15 (CKD)

Question 3

What are the symptoms of abnormal kidney function?

Answer 3

• Symptoms often present very late into disease
• Fatigue caused by anaemia
• Breathlessness due to metabolic acidosis and fluid retention
• Leg swelling due to fluid retention
• Nausea due to toxin retention
• Itch due to retained toxins
• bone pain due to Vitamin D deficiency

Question 4

Why does CKD cause anaemia?

Answer 4

• oxygen sensing apparatus doesn’t work properly
• less ertythropoetin generated by the kidneys and so less stimulus to bone marrow and red cell mass falls
• causing anaemia (normochromic and normocytic)

Question 5

What are the signs of abnormal kidney function?

Answer 5

• Pallor (anaemia)
• pitting oedema (salt and fluid retention)
• Hypertension (linked to salt and fluid retention)
• Proteinuria or haematuria (blood)

Question 6

What are the main causes of CKD?

Answer 6

1) diabetic kidney disease
2) Hypertensive and or atherosclerotic vascular disease of kidneys
3) Glomerulonephritis
4) polycystic kidney disease
5) Tubulointerstitial disease

Question 7

What are the risk factors for CKD?

Answer 7

• diabetes
• hypertension
• smoking
• dyslipidemia
• age
• male
• genetics
• cardiac disease (renal can also cause cardiac)

Question 8

What will histology of diabetic glomerulus show?

Answer 8

• mesangial cell expansion

- expansion of extracellular matrix around cell

Question 9

How does diabetes cause kidney disease?

Answer 9

Neuropathy in diabetics can cause development of nodules on the glomeruli this decreases the number of capillaries available for BF so GFR falls

Question 10

What is the pathology of diabetic nephropathy?

Answer 10

• rise in intraglomerular hypertension which causes glomerular scarring
• high blood glucose causes mesangial expansion and damage to basement membrane (causes thickening)

Question 11

What is the problem with a thickened basement membrane?

Answer 11

• basement membrane starts leaking so allows albumin to get into urine
• increases pressure in the glomeruli causing damage

Question 12

What is the problem with albumin in urine?

Answer 12

Proteinuria is toxic to tubules

Question 13

What is the result of progressive diabetic kidney disease?

Answer 13

• Tubular atrophy
• Fibrosis
• cellular infiltrate
• vasculopathy

Question 14

Why do ACE inhibitors help with CKD?

Answer 14

• ACE inhibitors and ARB are used to treat proteinuric renal disease
• block Ang II formation so allow efferent arteriole to vasodilate and reduce glomerular pressure

Question 15

What are the consequences of a reduced GFR?

Answer 15

Fluid retention:
- Heart failure 
- tissue oedema 
reduced metabolite excretion 
- uraemia 
- increased serum creatine 
- increased serum urate (can cause gout)
- increased drug levels due to prolonged T1/2

Question 16

What are the two key issues with drug prescribing in renal disease?

Answer 16

1) kidney failure prolongs T1/2 of many drugs leading to increased toxicity
2) some drugs make kidney failure worse by disturbing BF to kidney e.g. NSAIDS

Question 17

Consequences of reduced renal tubular failure?

Answer 17

reduced fluid reabsorption 
- polyuria
- nocturia
Reduced K+ excretion 
- hyperkalaemia 
reduced acid secretion and reduced bicarbonate formation 
- metabolic acidosis

Question 18

Renal bone disease pathology?

Answer 18

• reduced Vit D activation due to kidney damage
• decreased calcium absorption
• decreased mineralisation of bone (osteomalacia)
• reduced Levels of vitamin D and low calcium levels stimulate release of parathyroid hormone resulting in bone resorption

Question 19

What ion levels will increase in response to calcium?

Answer 19

phosphate

Question 20

How does calcium and phosphate levels impact Vit D production?

Answer 20

Low calcium = high phosphate = low Vit D production

High calcium = low phosphate = high vit D production

Question 21

What hormone is released as a result of low calcium and high Vit D

Answer 21

• Parathyroid hormone which will Bring up levels of calcium

- can get ectopic calcification of soft tissues

Question 22

How is CKD managed?

Answer 22

• treat hypertension
• slow progression of proteinuric renal disease using ACEi or ARB
• reduce associated CV risks e.g. statins for hyperlipideamia
• treat complications e.g. anaemia (Epo injections), renal bone disease (activated Vit D), hyperphosphataemia (phosphate binding drugs) and hyperkalaemia (restrict dietary intake)

Question 23

Renal replacement therapies for End-stage Renal disease?

Answer 23

Haemodialysis - vascular access e.g. arteriovenous fistula or central venous catheter
Peritoneal dialysis - catheter inserted into abdomen with incision below umbilicus to insert and exit site on right to left side of lower abdomen
Kidney transplant - placed in the left or right iliac fossa (palpable kidney underneath a surgical scar)

Question 24

What is the differences between hameodialysis and peritoneal dialysis?

Answer 24

H:
- hospital based
- nurse delivered 
- 3x week
- need access to blood
- very expensive 
- restricted to sites with dialysis machines 
P:
- Home-based 
- patient performs dialysis 
- daily
- uses abdominal cavity 
- cheaper
- can be done virtually anywhere

Question 25

Where do the donor kidney attach to?

Answer 25

common iliac artery (ectopic attachment site) use the donors renal vein and artery

Question 26

What are the benefits of kidney transplants?

Answer 26

• high success rate
• better quality of life for patient
• better survival for patients
• cheaper
  (downfall life long drug treatment to suppress immune system)

Question 27

How common is CKD?

Answer 27

10 % of adults