🎓
AKI
Renal
Reduced urine output
Confusion
Acute illness
Acute Kidney Injury (AKI) is a sudden decline in renal function. It is defined by a rise in serum creatinine or a fall in urine output. Causes are categorized into Pre-renal, Renal, and Post-renal.
🎯 Key Learning Objectives
- Diagnose AKI based on KDIGO criteria.
- Classify causes into Pre-renal (hypoperfusion), Renal (intrinsic), and Post-renal (obstruction).
- Identify and stop nephrotoxic medications (DAMN drugs).
- Manage life-threatening complications, particularly hyperkalaemia.
- Perform appropriate initial investigations, including a bladder scan.
- Recognize indications for urgent renal replacement therapy.
🔬 Pathophysiology
Decreased renal blood flow, direct tubular injury (e.g., Acute Tubular Necrosis), or obstruction to urinary outflow leads to a drop in Glomerular Filtration Rate (GFR) and accumulation of nitrogenous waste.
🩺 Clinical Features
Symptoms
- Oliguria
- Nausea
- Fatigue
- Confusion
- Fluid overload (dyspnoea)
Signs
- Dehydration (dry membranes, prolonged cap refill) OR fluid overload (JVP, oedema)
- Flank pain (if obstructive)
- Pericardial rub (uraemia)
🔬 Investigations
🛏️ Bedside
- Urine dipstick (protein/blood suggests renal cause)
- Bladder scan
- Fluid balance chart
🩸 Bloods
- U&Es (Creatinine)
- Full Blood Count
- Bicarbonate/Venous Blood Gas
- CK (if rhabdomyolysis suspected)
📷 Imaging
- Renal Ultrasound (within 24h if cause unclear or obstruction suspected)
⚗️ Special
- Autoimmune screen (ANCA, ANA) if vasculitis suspected
💊 Management
🚨 Acute Management
- Fluid resuscitation (if pre-renal)
- Treat hyperkalaemia (Calcium gluconate, Insulin/Dextrose)
- Catheterisation (if post-renal)
- Review/stop nephrotoxic drugs
📋 Long-Term
- Monitoring of renal function
- Pharmacist medication review
🏃 Lifestyle
- Avoid NSAIDs
- Sick day rules awareness
⚠️ Complications
Hyperkalaemia
Metabolic acidosis
Pulmonary oedema
Uraemic pericarditis
Chronic kidney disease progression
⭐ High-Yield Pearls
- The 'DAMN' drugs to stop: Diuretics, ACE-inhibitors/ARBs, Metformin, NSAIDs.
- AKI Stage 1: Creatinine 1.5-1.9x baseline. Stage 3: Creatinine >3x baseline.
- A urine dip exhibiting blood and protein without infection suggests glomerulonephritis.
- Pre-renal AKI is the most common form (80% of cases).
- Urgent dialysis indications (AEIOU): Acidosis, Electrolytes (K+), Intoxication, Overload, Uraemia.
📖 GUIDELINES:
NICE NG148
KDIGO AKI Guidelines
❓ Practice Questions
Q1. A 72-year-old man is admitted with a two-day history of vomiting and diarrhoea. His blood pressure is 95/60 mmHg and his heart rate is 105 bpm. Baseline creatin…
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Q2. A 65-year-old woman with chronic kidney disease (CKD) stage 4 is found to have a serum potassium of 6.8 mmol/L. Her ECG shows peaked T waves and a broadened QRS…
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Q3. A 45-year-old man presents with bilateral leg swelling and periorbital oedema. Urinalysis shows 4+ protein and 24-hour urinary protein is 4.5g. His serum albumi…
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