Types, Causes and Clinical Features of Acute Renal Failure (ARF)

Definition of Renal Failure:

Renal failure may be defined as failure to renal excretion leading to retention of nitrogenous waste products of metabolism including creatinine & urea.

Types of Renal Failure:

Kidney failure can be divided into two categories:

1. Acute kidney injury/acute renal failure:

Acute kidney injury (AKI), previously called acute renal failure (ARF), is a rapidly progressive loss of renal function, generally characterized by oliguria (decreased urine production, quantified as less than 400 mL per day in adults, less than 0.5 mL/kg/h in children or less than 1 mLkg/h in infants); and fluid and electrolyte imbalance.

2. Chronic kidney disease:

Chronic kidney disease (CKD) can also develop slowly and, initially, show few symptoms. CKD can be the long term consequence of irreversible acute disease or part of a disease progression.

Definition of Acute Renal Failure (ARF):

A significant deterioration of renal function occurring over hours or days, detected by a rising urea and creatinine, with or without oligura.

Acute renal failure (ARF) types
Fig: Acute renal failure (ARF) types

Classification or Causes of Renal Failure:

A) Pre-renal Acute Renal Failure:

1. Reduced circulatory blood volume (hypovolumia)

Haemorrhage from any causes:

  • GIT bleeding (Haematemesis, melaena),
  • Postpartum haemorrhage,
  • During surgery,
  • Trauma: Fracture of pelvis/ femur.

Loss of plasma as in burn and crushing injuries.

Sodium and water depletion:

  • From GIT: Severe vomiting, Diarrhea, Acute intestinal obstruction pancreatitis, Paralytic ileus, Fistulae.
  • In urine: Due to diuretics, diabetic ketoacidosis.
  • From skin: due to excess sweating.

2. Reduction in cardiac output:

3. Intravascular haemolysis

4. Rhabdomyolysis

5. Bilateral renal vessel occlusion (thrombosis, embolism)

B. Renal Acute Renal Failure:

Glomerulonephritis: Acute glomerulonephritis


  • Acute pyelonephritis,
  • Chronic pyelonephritis.


  • Vasculitis:
  • Renal arteriolar hypertension,
  • Malignant hypertension.

Tubular cells injury:

  • Ischemia,
  • Toxins: eg, aminoglycosides, sulphonamides.

Intra-luminal obstruction:

  • Precipitation of crystal,
  • Precipitation of protein – amyeloidosis.

Interstitial nephritis: Diffuse infections, Hypercalcacmia, drug

Others: Polycystic kidneys, renal tuberculosis, PAN

C. Post renal ARF:

Extra renal obstruction:

  • Prostatic enlargement,
  • Urethral stricture,
  • Tumour of prostate, pelvis, urinary bladder,
  • Calculi or blood clots,
  • Surgical accident.

Intra renal obstruction:

  • Crystal of uric acid,
  • Crustal of oxalic acid,
  • Bladder-rupture/ trauma.

Clinical Features of Acute Renal Failure:

a) Oliguric phase:

Urine volume markedly decrease to 200- 250 ml/day

After some days symptoms of uraemia develop:

  • Initially anorexia,
  • Nousea,
  • Vomiting,
  • Apathy,
  • Mental,
  • Confusion,
  • Fits,
  • Drowsiness coma and bleeding episodes.

Respiratory rate is often increased due to acidosis, respiratory infection

Danger of oliguria:

  • Pulmonary oedema,
  • Hyperkalaemia,
  • Anaemia,
  • Chance of systemic infection is more,
  • Uraemia and metabolic acidosis,
  • Renal cortical necrosis.

b) Recovery phase:

  • After 7- 20 days renal function returns
  • In a number of patients a diuretic phase develops
  • Urine output is frequently 3 – 5 liters/day
  • Usually persists for 3 – 5 days

Danger of diuretic phase:

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