Renal Failure: Introduction and Types

  • Renal failure is the failure of the kidney related to excretory functions.
  • It is generally understood as decrease in glomerular filtration rate (GFR) for which GFR is considered as the best index of renal failure.
  • During the initial stages of renal failure, decrease in GFR is not affected much.
  • But as the 50% of nephrons are affected, still there is decrease in GFR by only 20% to 30% which is due to compensatory mechanism provided by the unaffected nephrons.
  • Renal failure is generally understood as acute renal failure and chronic renal failure.
  • It is the condition which may be accompanied by some other complications which are as follows:

a) Deficiency of calcitriol (activated vitamin D) that results in reduction of the calcium absorption from the intestine leading to hypo-calcemia. This both condition may lead to hyperparathyroidism in some patients.

b) Deficiency of erythropoietin resulting to anemia.

c) Disturbances in acid-base balance.

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Acute Renal Failure (ARF)

  • Acute renal failure is the abrupt or stoppage of the renal functions suddenly which may get reverse within few days to few weeks.
  • Acute renal failure may need emergency treatment as it results in sudden life threatening reactions in the body.

Causes of ARF

i) Acute nephritis (inflammation of kidneys) developed by some immune reaction.

ii) Due to damage of renal tissues lead by poisons like lead and mercury.

iii) Some type of circulatory shock may result to renal ischemia.

iv) Burns, hemorrhage, snake bite, toxins and drugs lead to acute tubular necrosis.

v) Severe type of transfusion reactions.

vi) Drop in blood pressure suddenly due to hemorrhage, diarrhea, severe burns and cholera.

vii) Formation of calculi or tumor causing blockage of ureter.

Features of ARF

  • Oliguria (decreased urinary output).
  • Anuria (cessation of urine formation) in severe cases.
  • Proteinuria (appearance of proteins in urine) including albuminuria (excretion of albumin in urine).
  • Hematuria (presence of blood in urine).
  • Edema due to increased volume of extracellular fluid (ECF) caused by retention of sodium and water.
  • Hypertension within few days because of increased ECF volume.
  • Acidosis due to the retention of metabolic end products.
  • Coma due to severe acidosis resulting in death within 10 to 14 days if the patient is not treated in time.


Chronic Renal Failure (CRF)

  • It is the progressive, long standing and irreversible impairment of renal functions.
  • Loss in the function of some nephrons can be compensated by unaffected nephrons but when more and more nephrons start losing their function over the months or years, the compensatory mechanism by other unaffected nephron fails which results in the development of chronic renal failure.


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Causes of CRF

  • Chronic nephritis
  • Tuberculosis
  • Hypertension
  • Renal calculi
  • Atherosclerosis
  • Polycystic kidney disease
  • Urethral constriction
  • Slow poisoning by drugs or metals.

Features of CRF

  1. Uremia
  • It is the condition in which there is excess accumulation of end products of protein metabolism such as urea, nitrogen and creatinine in blood.
  • Sometimes deposition of some toxic substances like organic acids and phenols also cause this problem.
  • Uremia also occurs because of the failure of kidney to excrete the metabolic end products and toxic substances.
  • Features of uremia are: anorexia, lethargy, drowsiness, nausea and vomiting, pigmentation of skin, muscular twitching, tetany and convulsion, confusion, mental deterioration and coma.
  1. Acidosis: uremia results in acidosis which leads to coma and death.
  2. Edema: development of edema caused by kidney failure to excrete sodium and electrolytes resulting in increased extra cellular fluid.
  3. Blood loss: heavy loss of blood due to gastrointestinal bleeding accompanied by platelet dysfunction.
  4. Anemia: production of RBC is decreased due to the hamper in the secretion of erythropoietin by the kidney resulting to normocytic normochromic
  5. Hyperparathyroidism: deficiency of calcitriol leads to the development of secondary hyperparathyroidism which increases the removal of calcium from bones resulting in osteomalacia.





Renal Failure: Introduction and Types