Acute Kidney Injury and Chronic Kidney Disease
KDIGO definitions, causes and nursing care
Acute kidney injury (AKI)
KDIGO: creatinine rises ≥0.3 mg/dL within 48 h, or to ≥1.5× baseline within 7 days, or urine output <0.5 mL/kg/h for 6 h.
| Prerenal | ↓ blood flow: dehydration, bleeding, HF, shock. BUN:creatinine often >20:1 |
| Intrarenal | Kidney tissue damage: acute tubular necrosis (prolonged low flow, nephrotoxins: contrast, aminoglycosides, vancomycin, NSAIDs), glomerulonephritis |
| Postrenal | Obstruction: enlarged prostate, stones, tumors, blocked catheter |
Nursing care in AKI
- Strict I&O, daily weight, urine output hourly if critical.
- Watch for hyperkalemia (peaked T waves), fluid overload, metabolic acidosis.
- Avoid nephrotoxins; adjust drug doses to kidney function; check catheter patency first if urine stops.
- Phases: oliguric → diuretic (watch for dehydration, low K⁺ and Na⁺) → recovery.
Dialysis indications: AEIOU
Acidosis · Electrolytes (high K⁺) · Intoxication (dialyzable drugs) · Overload (fluid) · Uremia (confusion, pericarditis).
Chronic kidney disease (CKD): stages by GFR
| Stage | eGFR (mL/min/1.73 m²) | Meaning |
|---|---|---|
| G1 | ≥90 | Normal GFR with kidney damage (e.g., protein in urine) |
| G2 | 60–89 | Mildly decreased |
| G3a / G3b | 45–59 / 30–44 | Moderately decreased |
| G4 | 15–29 | Severely decreased: prepare for dialysis or transplant |
| G5 | <15 | Kidney failure |
GFR is how much blood the glomeruli filter per minute (not total blood flow). Albuminuria is staged A1–A3 (urine albumin-to-creatinine ratio <30, 30–300, >300 mg/g). Leading causes: diabetes and hypertension.
What goes wrong in CKD
- Anemia (less erythropoietin) → ESAs + iron; hold ESA if Hgb is high (~>11); raises BP and clot risk.
- High phosphate, low calcium → bone disease: phosphate binders with meals, active vitamin D.
- High K⁺, metabolic acidosis, fluid overload, hypertension.
- Uremia: fatigue, nausea, itching, confusion.
Slowing CKD Updated
- BP control; ACE inhibitor or ARB if albuminuria.
- SGLT2 inhibitor (with or without diabetes) for most with eGFR ≥20.
- In type 2 diabetes: finerenone; semaglutide (GLP-1 RA) also protects kidneys.
- Avoid: NSAIDs, magnesium laxatives and antacids, phosphate enemas; caution with contrast and metformin.
- Diet: limit sodium; K⁺ and phosphorus as labs require; protein ~0.8 g/kg before dialysis (higher once on dialysis).