Acute Kidney Injury (AKI) 🧪
Clinical guide for diagnosing and managing acute kidney injury. AKI staging, causes, investigations, treatment, and AKI calculator for NCHDs.
🧠 Definition & Relevance
- AKI is defined by a rapid decline in renal function over hours to days.
- KDIGO criteria: ↑ serum creatinine by ≥26.5 μmol/L within 48h, or ≥1.5x baseline in 7 days, or urine output <0.5 mL/kg/h for >6 hours.
- Important due to risk of fluid/electrolyte imbalance and need for timely intervention.
📞 What to Ask / Orders to Make
- Any recent nephrotoxic meds (e.g. NSAIDs, ACEi, contrast)?
- Fluid status and recent intake/output?
- Any previous renal function data?
- Ask nurse to: check catheter patency, input/output accuracy, perform bladder scan if needed.
📋 Causes (by category)
- Pre-renal: dehydration, hypovolaemia, heart failure
- Renal: sepsis, nephrotoxins, glomerulonephritis, rhabdomyolysis
- Post-renal: obstruction from prostate, stones, blocked catheter
🧾 History
- Symptoms: reduced urine output, confusion, lethargy, oedema
- Risk factors: recent illness, infection, fluid loss, medications
- Ask about urinary symptoms, previous AKI/CKD, recent imaging with contrast
🩺 Examination
- Vitals: HR, BP, temp, RR, SpO₂
- Fluid status: mucous membranes, JVP, oedema, cap refill
- Bladder palpation, DRE if obstructive cause suspected
🔍 Investigations
- Bloods: U&Es, creatinine, FBC, CRP, CK if rhabdo suspected
- Urinalysis ± urine microscopy
- Renal ultrasound if obstructive cause suspected
- ECG if hyperkalaemia suspected
- VBG for acid/base balance and lactate
💊 Initial Management
- Stop nephrotoxic drugs
- Volume resuscitation if hypovolaemic (250–500ml crystalloid)
- Insert/flush catheter if needed
- Treat sepsis or obstruction if present
- Monitor fluid balance and labs regularly
⚠️ When to Escalate
- Hyperkalaemia or severe acidosis
- Volume overload with pulmonary oedema
- Severe or persistent AKI (Stage 2–3)
- Suspected need for dialysis
- Obstructive cause with no response to initial management
AKI Calculator
Calculate acute kidney injury stage
Assessment Result
Enter at least creatinine or urine data.