Kidney disease and renal failure

Question 1

What is eGFR calculated from?

Answer 1

Creatinine
Age
Gender
Ethnicity

Question 2

Explain 7 consequences of loss of renal function

Answer 2

1. Salt and water retention
   - Hyper-reninaemia
   - Inability to concentrate urine when nephrons are damage, causes nocturia due to loss of diurnal rhythm
   - Inability to excrete water, this causes dilutional hyponatraemia and oedema
   - Hypertension
2. Renal anaemia
   - Reduced erythrocytes leads to hypoxia as there is reduced O2 delivery to tissues
   - Risk of left ventricular hypertrophy and CV disease as cardiac output must increase to improve O2 delivery
   - Treated with recombinant EPO
3. Renal mineral bone disease
   - Kidney should metabolises vitamin D into its active form which will trigger Ca2+ absorption from the gut
   - PTH (regulates serum Ca2+) will act on the bones instead of Ca2+ as there is little around, demineralising them to release Ca2+ and increase serum Ca2+ conc
   - Kidneys also cannot excrete phosphate, this coupled with bone demineralisation will increase bone fragility and CV disease
4. Hypertension
   - Due to sodium retention
   - Due to RAAS activation
   - Due to volume expansion
   - Due to sympathetic NS activity
   - Due to endothelial dysfunction
   - Hypertension drives decline of kidney function, also contributes to CV risk (stroke, MI, heart failure)
5. Excretory function
   - Leads to accumulation of toxins
   - Creatinine rises
   - Retention of nitrogenous wastes
   - Retention of urate
   - Retention of phosphate
   - Reduced drug metabolism (opiates, insulin, antibiotics)
   - SIDE EFFECT OF REDUCED CLEARANCE CAN BE HYPOGLYCAEMIA
6. Electrolyte abnormalities
   - HYPOcalcaemia = loss of vit D activation results in less Ca2+ absorption from gut. Can lead to cardiac arrhythmias, muscle spasm, and paraesthesia
   - HYPERphosphataemia = Bone abnormalities, increased CVD risk
   - HYPO/HYPERnatraemia = neurological dysfunction
   - HYPO/HYPERkalaemia = muscle dysfunction, cardiac arrhythmias
7. Metabolic abnormalities
   - Kidneys usually responsible for acid clearance
   - Failure to excrete H+ causes an increase in CO2, which is removed by the lungs to maintain pH, causing symptoms:
   Increased respiratory drive
   Breathlessness
   Chest pain
   Confusion
   Bone pain
   Demineralisation of bone

Question 3

Requirements for CKD

Answer 3

• eGFR of <60ml/min/1.73m^2 or kidney damage which must be present for >= 3months
• Irreversible and tends to progress