Why do you get hypocalcaemia in CKD?
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
How can you interrogate the kidney function?
Bloods - Creatinine, eGFR
Urine - Albuminuria, haematuria
US - Size
How do you determine the eGFR?
Serum creatinine equated with a number of other factors eg weight, height, ethnicity
What is the cut of a normal eGFR?
>90 is normal
What is the normal size of the kidney?
What is the blood pressure target in kidney disease?
What are the stages of CKD?
1. eGFR = >90ml/min, with proteinuria
2. eGFR = 60-90
3. eGFR = 30-60
4. eGFR = <30
5. eGFR = <15
What is the ACEi of choice in CKD?
What does urea accumulation cause?
At which stage of CKD might you expect EPO deficiency?
What does high phosphate cause?
Conjugates with Ca and deposits in soft tissues - attributes to IHD and renal osteodystrophy
Why does bicarb drop in CKD? What are some implications?
Decreased carbonic anhydrase = decreased production
Harder to compensate for acidosis
Which big classes of drugs are renally excreted?
Enoxaparin (reduce to 40mg)
What is H+ exchanged with in the kidney?
What happens to PO4 in CKD?
Can't excrete therefore it goes up
What happens to vitamin D in the kidney?
Vitamin D2 (from skin, liver) is activated to D3 (required from Ca absorption in SI)
What is the consequence of vitamin D2 not being activated in CKD?
Renal osteodystrophy due to reduced absorption of Ca in the SI (among other things)
What is causes the increased CVD risk in CKD?
Ca3(PO4)2 deposition in the soft tissue
What are the principles of treatment of CKD?
Treat underlying cause
- eg control BSL
Prevent further damage
- ACEi and ARB
- Control BSL
Avoid renally excreted/nephrotoxic drugs