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Symptoms of acute renal failure
Last reviewed: 06.07.2025
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During acute renal failure, 4 stages are distinguished:
- initial - the effect of a damaging agent on the epithelial cells of the tubules (duration is several hours);
- oligoanuric - maintenance of a relatively low SCF, against the background of decreased diuresis, azotemia increases (this stage can last for several days, in the case of dialysis, the next stage may develop);
- polyuric - restoration of the water-excreting function of the kidneys (lasts several weeks; about 80% of patients during this period suffer from some kind of infection, which can be the cause of death);
- recovery - the stage of slow restoration of normal glomerular filtration rate and tubular functions (duration is 6-24 months).
In the initial stage of acute renal failure, the clinical picture is dominated by the symptoms of the pathological process complicated by kidney damage, so oliguria, metabolic acidosis, hyperkalemia and azotemia are usually obscured by the manifestations of the underlying disease. Oliguria less than 0.3 ml / (kg h) is the main clinical manifestation of acute renal failure. In the oligoanuric stage, a decrease in diuresis and an increase in azotemia, phenomena of uremic intoxication predominate. Mortality is highest during this period. With adequate treatment, the oligoanuric stage is followed by polyuric acute renal failure, in which diuresis is 2-3 times higher than the age norm and is combined with low urine osmolarity. Hyponatremia is replaced by hypernatremia, and hyperkalemia is replaced by hypokalemia. At this stage, there is no noticeable improvement in the child's condition, lethargy, muscle hypotonia, hyporeflexia, paresis and paralysis persist. There are high levels of azotemia in the blood, and a lot of protein, leukocytes, erythrocytes, and cylinders in the urine, which is associated with the release of dead cells of the tubular epithelium and the resorption of infiltrates. At this stage, infection often accumulates until a septic condition develops. The duration of the recovery stage is from several months to several years until the complete restoration of nephron function.
In uncomplicated cases, metabolic acidosis is detected in the blood against the background of acidotic breathing and respiratory alkalosis. In complicated cases, acidosis is replaced by metabolic alkalosis (prolonged vomiting) or is combined with respiratory acidosis (pulmonary edema). Changes in electrolyte metabolism are characterized by hyponatremia, hypochloremia, hypermagnesemia, hyperphosphatemia, hypocalcemia, which are combined with clinical symptoms reflecting the effect of these disorders on the central nervous system and blood circulation (somnolence or coma, convulsions, cardiac arrhythmia). Most children also have hyperkalemia, but in some newborns, despite a sharp decrease in diuresis, hypokalemia occurs (due to vomiting and profuse diarrhea).
Uremic intoxication is expressed in the appearance of skin itching, anxiety or lethargy, uncontrollable vomiting, diarrhea, and signs of cardiovascular failure.
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