Acute renal failure (ARF)

Acute Renal Failure (ARF), currently referred to as Acute Kidney Injury (AKI), is an abrupt decline in kidney function resulting in reduced glomerular filtration rate (GFR), accumulation of metabolic waste products, electrolyte imbalance, and disturbance of fluid homeostasis.

The condition is potentially reversible if recognized early and appropriately managed but may rapidly progress to life-threatening complications or chronic kidney disease.

Common causes include:

• Dehydration and severe fluid loss

• Drug or toxin exposure

• Urinary tract obstruction

• Acute glomerulonephritis (especially in children)

• Severe infections and systemic illness

Classification (Based on Cause)

1. Pre-renal AKI (Most Common)

Reduced renal perfusion without intrinsic kidney damage:

• Dehydration

• Hemorrhage

• Sepsis

• Heart failure

• Shock

2. Intrinsic Renal AKI

Direct kidney tissue injury:

• Acute tubular necrosis

• Glomerulonephritis

• Interstitial nephritis

• Nephrotoxic drugs

3. Post-renal AKI

Obstruction of urinary outflow:

• Prostatic enlargement

• Urinary stones

• Tumours

• Urethral obstruction

Pathophysiology

Reduced renal perfusion or direct renal injury leads to:

• Decreased filtration pressure

• Retention of urea and creatinine

• Fluid overload

• Metabolic acidosis

• Hyperkalaemia

• Uraemic toxin accumulation

Untreated AKI may result in multi-organ dysfunction.

Risk Factors

• Advanced age

• Severe dehydration

• Sepsis

• Major surgery or trauma

• Diabetes mellitus

• Hypertension

• Chronic kidney disease

• Use of nephrotoxic drugs:

  • NSAIDs

  • Aminoglycosides

  • Contrast media

• Urinary tract obstruction

• Burns or severe infections

• Childhood infections causing glomerulonephritis

Signs and Symptoms

Renal Manifestations

• Oliguria (<400 mL/day)

• Anuria

• Dark or reduced urine output

Fluid Overload

• Peripheral oedema

• Facial swelling

• Pulmonary oedema

• Weight gain

Systemic Features

• Fatigue

• Nausea and vomiting

• Confusion

• Hypertension

• Shortness of breath

Severe Features

• Convulsions (especially in children)

• Arrhythmias (hyperkalaemia)

• Coma

• Uraemia

Diagnostic Criteria

Clinical suspicion supported by:

• Oedema

• Oliguria or anuria

• Rising serum creatinine

• Electrolyte abnormalities

• Convulsions in children

(Standard KDIGO definition includes rise in creatinine ≥0.3 mg/dL within 48 hours or urine output reduction.)

Investigations

Essential Investigations

• Serum electrolytes

• Blood urea nitrogen (BUN)

• Serum creatinine

• Urinalysis

• Fluid balance monitoring

Imaging

• Renal ultrasound(to exclude obstruction, hydronephrosis, or structural abnormalities)

Additional Tests

• Complete blood count

• Arterial blood gases

• ECG (hyperkalaemia effects)

• Infection screening

• Autoimmune screening when indicated

Management

Management is a medical emergency aimed at:

1. Stabilization

2. Preventing further kidney injury

3. Treating complications

4. Managing underlying cause

Immediate Supportive Management

• Give oxygen if respiratory distress present

• Nurse patient in semi-Fowler’s position

• Strict fluid balance monitoring

• Daily weight monitoring

• Stop nephrotoxic medications

Fluid and Dietary Management

• Do NOT routinely administer IV fluids unless dehydration is confirmed

• Avoid unnecessary fluid infusion

• Restrict fluid intake:

10 mL/kg/day + visible fluid losses

• Stop intake of:

  • Salt

  • Potassium-containing foods

  • Excess fluids

Pharmacological Management

1. Hypertension

If:

• Diastolic BP >100 mmHgOR

• Systolic BP >150 mmHg

→ Amlodipine 5 mg orally

2. Fluid Overload / Respiratory Distress

Signs:

• Orthopnoea

• Rapid breathing

• Pulmonary congestion

Treatment:

• Furosemide 80 mg IV bolus

(May repeat under monitoring)

3. Management of Complications

Hyperkalaemia

• Cardiac monitoring

• Emergency correction protocols

Metabolic Acidosis

• Specialist-guided bicarbonate therapy

Uraemia

• Dialysis if severe

Indications for Dialysis

Urgent renal replacement therapy is required if:

• Refractory fluid overload

• Severe hyperkalaemia

• Severe metabolic acidosis

• Uraemic encephalopathy

• Pericarditis

• Persistent oliguria/anuria

Non-Pharmacological Management

• Oxygen therapy when indicated

• Semi-Fowler positioning

• Strict salt restriction

• Potassium restriction

• Controlled fluid intake

• Nutritional support

• Close monitoring of urine output

Referral

All suspected ARF/AKI patients require referral where adequate laboratory and specialist services exist.

Urgent referral if:

• Anuria

• Convulsions

• Pulmonary oedema

• Severe electrolyte imbalance

• Suspected obstruction

• Need for dialysis

• Rapidly rising creatinine

Complications

• Hyperkalaemia

• Pulmonary oedema

• Metabolic acidosis

• Uraemia

• Cardiac arrhythmias

• Chronic kidney disease

• Multi-organ failure

• Death

Prevention

• Early treatment of dehydration

• Avoid unnecessary nephrotoxic drugs

• Adequate hydration during illness

• Monitoring kidney function in high-risk patients

• Safe use of contrast agents

• Early relief of urinary obstruction

• Infection prevention and treatment

Prognosis

Outcome depends on:

• Cause of injury

• Speed of diagnosis

• Patient comorbidities

• Availability of dialysis

Early intervention often results in complete renal recovery, while delayed treatment may lead to permanent kidney damage.