Renal failure; Causes and Treatment
Renal failure refers to failure of excretory functions of kidney. It is usually, characterized by decrease in glomerular filtration rate (GFR). So GFR is considered as the best index of renal failure. However, decrease in GFR is not affected much during the initial stages of renal failure. If 50% of the nephrons are affected, GFR decreases only by 20% to 30%. It is because of the compensatory mechanism by the unaffected nephrons.
The renal
failure may be either acute or chronic.
Renal
failure is always accompanied by other complications such as:
1. Deficiency of calcitriol (activated vitamin D) resulting in reduction of calcium absorption from intestine and hypocalcemia. Deficiency of calcitriol and hypocalcemia may cause secondary hyperparathyroidism in some patients
2.
Deficiency of erythropoietin resulting in anemia
3. Disturbances in acidbase balance.
ACUTE RENAL FAILURE
Acute renal failure is the abrupt or sudden stoppage of renal functions. It is often reversible within few days to few weeks. Acute renal failure may result in sudden life-threatening reactions in the body with the need for emergency treatment.
CAUSES
1. Acute nephritis (inflammation of kidneys), which usually develops by immune
reaction
2. Damage
of renal tissues by poisons like lead, mercury and carbon tetrachloride
3. Renal
ischemia, which develops during circulatory shock
4. Acute tubular necrosis (necrosis of tubular cells in kidney) caused by burns, hemorrhage, snake bite, toxins (like insecticides, heavy metals and carbon tetrachloride) and drugs (like diuretics, aminoglycosides and platinum derivatives)
5. Severe transfusion
reactions
6. Sudden
fall in blood pressure during hemorrhage, diarrhea, severe burns and cholera
7.
Blockage of ureter due to the formation of calculi (renal stone) or tumor.
FEATURES
1. Oliguria (decreased urinary output)
2. Anuria (cessation of urine formation) in severe cases
3. Proteinuria
(appearance of proteins in urine) including albuminuria
(excretion of albumin in urine)
4. Hematuria (presence of blood in urine)
5. Edema due to increased volume of extracellular fluid (ECF) caused by
retention of sodium and water
6. Hypertension
within few days because of increased ECF volume
7. Acidosis due to the retention of metabolic end products
8. Coma due to severe acidosis (if the patient is not treated in time) resulting
in death within 10 to 14 days.
CHRONIC RENAL FAILURE
Chronic renal failure is the progressive, long standing and irreversible impairment of renal functions. When some of the nephrons loose the function, the unaffected nephrons can compensate it. However, when more and more nephrons start losing the function over the months or years, the compensatory mechanism fails and chronic renal failure develops.
CAUSES
1. Chronic
nephritis
2.
Polycystic kidney disease
3. Renal
calculi (kidney stones)
4.
Urethral constriction
5.
Hypertension
6.
Atherosclerosis
7.
Tuberculosis
8. Slow
poisoning by drugs or metals.
FEATURES
1. Uremia
Uremia is the condition characterized by excess accumulation of end products of protein metabolism such as urea, nitrogen and creatinine in blood. There is also accumulation of some toxic substances like organic acids and phenols. Uremia occurs because of the failureof kidney to excrete the metabolic end products and toxic substances.
Common
features of uremia
i.
Anorexia (loss of appetite)
ii.
Lethargy
iii.
Drowsiness
iv. Nausea
and vomiting
v.
Pigmentation of skin
vi.
Muscular twitching, tetany and convulsion
vii.
Confusion and mental deterioration
viii.
Coma.
2. Acidosis
Uremia
results in acidosis, which leads to coma and death.
3. Edema
Failure of kidney to excrete sodium and electrolytes causes increase in extracellular fluid volume resulting in development of edema.
4. Blood Loss
Gastrointestinal
bleeding accompanied by platelet dysfunction
leads to heavy loss of blood.
5. Anemia
Since, erythropoietin is not secreted in the kidney during renal failure, the production of RBC decreases resulting in normocytic normochromic anemia.
6. Hyperparathyroidism
Secondary hyperparathyroidism is developed due to the deficiency of calcitriol (1,25dihydroxycholecalciferol). It increases the removal of calcium from bones resulting in osteomalacia.
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