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People with prerenal azotemia have an abnormally high level of nitrogenous wastes such as urea and creatinine in their blood. These types of waste are potentially toxic when present in the blood in large quantities, so this condition can be serious. Prerenal azotemia is a common blood disorder in people who have been hospitalized as a result of kidney failure or conditions that affect blood flow to the kidneys such as burns, dehydration, hemorrhage and chronic diarrhea or vomiting.
Along with the liver, the kidneys are instrumental in filtering the blood and removing potentially harmful substances. If blood flow to the kidneys is reduced, the ability of the kidneys to filter the blood also is impaired. Waste and toxins that normally would be removed remain in the blood, and urine output is severely reduced, leading to abnormal fluid retention. When blood levels of urea and creatinine are abnormally high, as in prerenal azotemia, these toxic substances can impair organ function and damage tissues.
Common symptoms of azotemia include reduced alertness, confusion, fatigue and thirst. People with this condition also are likely to have reduced urine output, a dry mouth, pale skin, swelling caused by fluid retention, increased night-time urination and a rapid pulse. Other possible symptoms include abdominal pain, low blood pressure, dry mucous membranes and reduced skin elasticity.
This condition generally is diagnosed on the basis of blood tests for creatinine and urea as well as tests to check creatinine and sodium levels in the urine. In addition, kidney function tests and blood osmality tests might be carried out. The blood osmality test checks the concentration of all particles in the blood and is carried out to evaluate the body’s fluid balance, which is affected by hydration levels and kidney function.
The main objective in treating prerenal azotemia is to correct the cause of the imbalance as quickly as possible in order to prevent permanent kidney damage. Treatment often includes one or more sessions of dialysis to reduce the toxin load in the blood. If the cause of the condition is blood or fluid loss, treatment might involve a transfusion of blood or blood products or the administration of other intravenous fluids to restore blood volume and improve the balance of nitrogenous wastes in the blood.
When the cause of azotemia can be treated quickly and successfully, the condition can be reversed and permanent kidney damage prevented. For treatment to be successful, however, it typically must be administered within 24 hours of the first signs of azotemia occurring. Prerenal azotemia can be complicated by acute renal failure or acute tubular necrosis. This latter condition occurs when kidney tissue begins to die off, so it therefore is associated with permanent and irreversible kidney damage.