Renal failure: acute kidney injury and chronic kidney disease
Renal failure means the kidneys cannot clear waste and water: suddenly (AKI) or slowly (CKD). Protein, sodium, potassium, phosphorus and fluid are set by the stage and by dialysis.
At a glance
CKD stages and protein advice
| Stage | GFR (mL/min/1.73 m²) | Meaning | Protein advice |
|---|---|---|---|
| G1 | 90 or more | Kidney damage, normal GFR | About 0.8 g/kg, the normal adult amount (KDIGO: avoid over 1.3 g/kg); control sugar and BP |
| G2 | 60-89 | Mildly reduced | About 0.8 g/kg; avoid high-protein diets (over 1.3 g/kg, KDIGO) |
| G3a and G3b | 45-59 and 30-44 | Moderately reduced | 0.55-0.6 g/kg; diabetics 0.6-0.8 g/kg (KDOQI 2020) |
| G4 | 15-29 | Severely reduced | 0.55-0.6 g/kg (or 0.28-0.43 g/kg with keto-acid analogues under supervision), KDOQI 2020 |
| G5 not on dialysis | Under 15 | Kidney failure | As G4 |
| G5 on dialysis | Under 15 | Haemodialysis or peritoneal dialysis | 1.0-1.2 g/kg (KDOQI 2020), because dialysis removes amino acids |
Worked example: protein and energy by stage
Mr. Kumar weighs 60 kg (no oedema) and has non-diabetic CKD stage 4. Find his protein and energy needs now, and his protein need after he starts haemodialysis.
- Protein now (0.55-0.6 g/kg): 0.55 × 60 = 33 g; 0.6 × 60 = 36 g. So 33-36 g a day, at least half from good-quality sources (milk, egg white, curd, paneer).
- Energy (25-35 kcal/kg): 30 × 60 = 1,800 kcal a day, mainly from carbohydrate and fat so protein is not burned for energy.
- On haemodialysis (1.0-1.2 g/kg): 1.0 × 60 = 60 g; 1.2 × 60 = 72 g. So 60-72 g a day.
- Protein must almost double once dialysis starts, because each session removes amino acids.
Before dialysis: about 33-36 g protein and 1,800 kcal a day. On haemodialysis: about 60-72 g protein a day. Older Indian books give about 0.6 g/kg before dialysis (36 g for him), which is similar.
Dietary principles
| Nutrient | AKI | CKD not on dialysis | On dialysis |
|---|---|---|---|
| Energy | 20-30 kcal/kg (KDIGO 2012) | 25-35 kcal/kg | 25-35 kcal/kg |
| Protein | 0.8-1.0 g/kg without dialysis; 1.0-1.5 g/kg with dialysis; up to 1.7 g/kg if very catabolic (KDIGO 2012) | 0.55-0.6 g/kg (0.6-0.8 in diabetics) | 1.0-1.2 g/kg |
| Sodium | Restricted in oliguria | Under 2.3 g sodium a day (KDOQI 2020) | Under 2.3 g sodium a day |
| Potassium | Restricted in oliguria; replaced in the diuretic phase | Restrict if blood potassium is high; leach vegetables | Usually restricted (more with haemodialysis) |
| Phosphorus | As per blood levels | Restrict when high (older KDOQI figure about 800-1,000 mg a day; KDOQI 2020 adjusts to blood levels); avoid colas and processed foods | Restrict; phosphate binders with meals |
| Fluid | Previous day's urine + about 500 mL in oliguria | Usually not restricted until urine falls | Urine output + about 500-750 mL; limit weight gain between sessions |
| Vitamins and minerals | As needed | Iron for anaemia; vitamin D as prescribed | Water-soluble vitamins (B-complex, C) lost in dialysis are replaced |
Foods, leaching and a sample menu (CKD stage 4, not on dialysis)
| Item | Details |
|---|---|
| Include | Rice, idli, rava (semolina), sago, refined-flour chapati; measured milk and curd; egg white; lower-potassium vegetables (bottle gourd, ridge gourd, cabbage) after leaching; apple, pear |
| Avoid or limit | Banana, tender coconut water, orange, sweet lime, dry fruits, potato, tomato in large amounts, whole pulses and dals in excess, colas, processed cheese, salted snacks, pickles, salt substitutes (potassium chloride) |
| Leaching vegetables | Peel, cut into small pieces, soak in plenty of warm water for about 2 hours, discard the water, boil in fresh water and discard again; this removes much of the potassium |
| Breakfast | Idli (3) with mint chutney (no tomato); tea with a little milk |
| Mid-morning | Apple (small) |
| Lunch | Rice, leached bottle gourd kootu with a small amount of dal, cabbage poriyal, a small cup of curd |
| Evening | Sago (sabudana) kheer with a little milk |
| Dinner | Chapati (2), leached cauliflower-beans curry, egg-white bhurji |
On the dialysis unit, the dietitian checks weight gain between sessions (fluid), and potassium and phosphorus reports each month, then adjusts the plate. Patients must learn that protein goes up after dialysis starts, not down.
2 marks: “What is leaching of vegetables?” Peeling, cutting small, soaking in plenty of warm water and boiling in fresh water, discarding the water each time, to remove potassium.
5 marks: “Explain the dietary management of acute kidney injury.” Causes and phases; energy 20-30 kcal/kg; protein by dialysis status; sodium, potassium and fluid restriction in oliguria; replacement in the diuretic phase.
10 marks: “Discuss the causes, symptoms and dietary management of chronic kidney disease.” Define, KDIGO stages, causes, symptoms, protein by stage with a calculation, energy, sodium, potassium (leaching), phosphorus, fluid, dialysis changes, foods, menu.
Kidney diet watches PPS-F: Protein, Potassium and phosphorus, Sodium, Fluid. Before dialysis protein goes down; on dialysis it goes up.