Features of Acute Renal Failure

Acute renal failure (ARF) is a syndrome in which accumulation of nitrogenous wastes lead to rapid deterioration of the kidney function. It is a reversible syndrome characterized by an abrupt loss of renal function. This may occur in all ages and both sexes.

The condition appears in patients with pre-existing renal disease. Other common causes include sepsis, drug toxicity and obstruction to the urine flow.

Acute renal failure may be pre-renal, intrinsic or post-renal.

Pre-renal failure is caused due to decreased renal plasma flow, which may be due to volume depletion, decreased cardiac output or decrease in intravascular volume.

Intrinsic failure results from some disease in the kidney itself, most commonly injury to the nephrons.

Post-renal failure is caused due to obstruction to the urine outflow, which may occur commonly because of enlarged prostrate, some gynecological disorder or renal stones.

Clinical features appear depending upon the underlying cause. These may include hypotension, congestive failure or renal artery stenosis. Anuria (no urine), oliguria (decreased urine) or polyuria (excess urine) may occur. However, normal urine output is also noticed in some cases.

Other symptoms may include malaise, fatigue, nausea, vomiting, arthralgia, rhinitis, hiccups, diarrhoea, backache, headache, delirium, confusion, drowsiness and anorexia. Sometimes, fever and rash may also appear.

Urinary failure along with fractional excretion of sodium (less than 1%) suggests pre-renal failure and sodium excretion (more than 1%) suggests renal parenchymal disease. Presences of hyaline casts in the urine are also suggestive of pre or post renal failure.

If there are erythrocytes (RBCs) in the urine, it indicates the presence of calculi, trauma, tumour or some infection. The leucocytes (WBCs) presence indicates infection, inflammation or allergy.

Dietary advice in ARF includes sodium restriction in case of hypertension, oliguria and oedema. Salty biscuits, meat and pickles are not permitted. Even food rich in potassium is to be restricted. Carbohydrates should constitute the main source of calories.

Urgent treatment is necessary for sepsis, shock, seizures and pulmonary oedema. Poor prognosis is seen in patients above 50 years of age, oliguria for more than two weeks, infection, burns, jaundice, continuously rising urea levels and in case of multi-organ failure.