ABCs
- Check vitals to assess for instability (e.g., hypotension, tachycardia, hypoxia)
- Place the patient on a cardiac monitor if unstable
- Document urine output
- Oliguria < 0.5 mL/kg/hr for ≥6 hours
- Anuria < 100 mL/day
HPI & Examination
- Assess fluid balance
- Fluid intake vs. losses (e.g., vomiting, diarrhea, diuresis, bleeding)
- Recent events
- Hypotension, sepsis, surgery, trauma
- History of CKD or ESRD
- Catheter check
- Foley use → rule out kinking, blockage, or displacement
- Medication review
- Nephrotoxins: NSAIDs, ACEi/ARB, aminoglycosides, IV contrast
- Diuretics: May cause pre-renal AKI if overused
- Volume status
- Dehydration → dry mucosa, low JVP, tachycardia
- Fluid overload → edema, raised JVP, crackles
- Bladder distension
- Palpation/percussion
- A bedside bladder scan is if unclear
Investigations
- Renal panel (Urea, Creatinine, Electrolytes)
- Urinalysis ± Urine Culture (casts, protein, infection)
- Venous Blood Gas (VBG) ± Lactate → check acidosis
- ECG → look for hyperkalemia
- Ultrasound KUB → if post-renal obstruction suspected
Management
| Type | Common Causes | Clues | Management |
|---|---|---|---|
| Pre-Renal | Hypovolemia, sepsis, hypotension, heart failure, hepatorenal syndrome | Dry mucosa, tachycardia, low BP, high urea:creatinine ratio | IV fluids, address underlying cause (e.g., infection, bleeding) |
| Intrinsic Renal | ATN (ischemia, contrast, sepsis), AIN (drugs, infection), Glomerulonephritis | Urine casts (muddy or RBC), proteinuria, eosinophilia, rising creatinine | Stop nephrotoxins, consider steroids for AIN, nephrology referral for GN |
| Post-Renal | BPH, ureteric stones, malignancy, neurogenic bladder | Distended bladder, minimal output despite Foley, hydronephrosis on ultrasound | Foley insertion, bladder scan, renal imaging, urology consultation |
Fluid & Electrolyte Management
- Volume depletion: Start IV fluids (NS or balanced solution)
- Hyperkalemia or acidosis: Treat urgently (calcium gluconate, insulin/glucose, sodium bicarbonate, dialysis if needed)
- Post-obstructive diuresis: Monitor output closely and replace 1:1
Escalation & When to Seek Help
| Trigger | Action |
|---|---|
| Persistent oliguria despite fluids | Call Nephrology |
| Anuria despite Foley insertion | Suspect upper tract obstruction → Urology consult |
| Severe electrolyte derangements, uremia | Consider ICU / urgent dialysis |
| Suspected GN (RBC casts, HTN, proteinuria) | Nephrology + possible biopsy |