Chronic Kidney Disease

Question 1

Why do you get hypocalcaemia in CKD?

Answer 1

Phosphate isn’t excreted in the kidney

High phosphate stimulates PTH secretion

PTH stimulates osteolysis to increase serum Ca

Total Ca falls and osteoporosis occurs

Ca combines with PO4 and deposits in tissue

Damaged kidney doesn’t reabsorb as much Ca

Ca binds to albumin and is lost

Vitamin D isn’t activated > less Ca

Question 2

How can you interrogate the kidney function?

Answer 2

Bloods - Creatinine, eGFR

Urine - Albuminuria, haematuria

US - Size

Biopsy

Question 3

How do you determine the eGFR?

Answer 3

Serum creatinine equated with a number of other factors eg weight, height, ethnicity

Question 4

What is the cut of a normal eGFR?

Answer 4

>90 is normal

Question 5

What is the normal size of the kidney?

Answer 5

12cm

Question 6

What is the blood pressure target in kidney disease?

Answer 6

<125/75

Question 7

What are the stages of CKD?

Answer 7

1. eGFR = >90ml/min, with proteinuria
2. eGFR = 60-90
3. eGFR = 30-60
4. eGFR = <30
5. eGFR = <15

Question 8

What is the ACEi of choice in CKD?

Answer 8

Ramipril

Question 9

What does urea accumulation cause?

Answer 9

Itch

Serositis

Encephalopathy

Question 10

At which stage of CKD might you expect EPO deficiency?

Answer 10

3b

Question 11

What does high phosphate cause?

Answer 11

Increase PTH

Hypocalcaemia

Conjugates with Ca and deposits in soft tissues - attributes to IHD and renal osteodystrophy

Question 12

Why does bicarb drop in CKD? What are some implications?

Answer 12

Decreased carbonic anhydrase = decreased production

Harder to compensate for acidosis

Question 13

Which big classes of drugs are renally excreted?

Answer 13

Enoxaparin (reduce to 40mg)

NOAC

B-lactams

Metformin

Question 14

What is H+ exchanged with in the kidney?

Answer 14

K+

Question 15

What happens to PO4 in CKD?

Answer 15

Can’t excrete therefore it goes up

Question 16

What happens to vitamin D in the kidney?

Answer 16

Vitamin D2 (from skin, liver) is activated to D3 (required from Ca absorption in SI)

Question 17

What is the consequence of vitamin D2 not being activated in CKD?

Answer 17

Renal osteodystrophy due to reduced absorption of Ca in the SI (among other things)

Question 18

What is causes the increased CVD risk in CKD?

Answer 18

Ca3(PO4)2 deposition in the soft tissue

Question 19

What are the principles of treatment of CKD?

Answer 19

Treat underlying cause

• eg control BSL

Prevent further damage

• ACEi and ARB
• Control BSL
• Lipids

Prevent CVD

• Statins

Lifestyle control

Mx Complications

Avoid renally excreted/nephrotoxic drugs