Why this test?
- To assess kidney function in a number of conditions (along with a creatinine test).
- For the diagnosis of kidney disease and to check the condition of patients with chronic or acute renal failure.
In what cases is it prescribed?
Urea is checked during a biochemical study: in case of non-specific complaints, in the assessment of kidney function before prescribing drug therapy, before hospitalization of a patient due to an acute illness, when a person is in a hospital.
With symptoms of impaired kidney function: weakness, fatigue, reduced attention, poor appetite, sleep problems, swelling of the face, wrists, ankles, ascites, foamy, red or brown urine, decreased diuresis, problems with urination (burning, intermittent, predominance of nocturnal diuresis, pain in the area of the kidneys (especially on the sides of the spine), under the ribs, high pressure.
In addition, this analysis can be carried out periodically: to check the condition of patients with chronic kidney diseases or chronic non-renal diseases such as diabetes, congestive heart failure, myocardial infarction, hypertension, etc., before and during drug therapy to determine the state of kidney function, after dialysis sessions to evaluate their effectiveness.
Urea is one of the final products of protein metabolism containing nitrogen. It is produced in the liver, transported by blood to the kidneys, filtered there through the glomerulus, and then excreted. The result of the blood urea test is an indicator of glomerular production and urine excretion. Metabolized nitrogen is in the body in the form of ammonia, produced from the remains of the breakdown and processing of proteins. Ammonia in the liver, combining with carbon dioxide, forms urea.
Rapid protein breakdown and kidney damage rapidly raise blood urea levels (as does almost any massive cell death). The amount of excreted urea is directly dependent on the level of protein consumed by a person, the causes of increased urea in the blood are febrile conditions, complications of diabetes, increased hormonal function of the adrenal glands.
An increased level of urea is a marker of reduced glomerular filtration. Urea is one of the main metabolites of blood, the body does not use it in any way, but only gets rid of it. Since this excretion process is continuous, a certain amount of urea is normally always in the blood. The level of urea should be interpreted inseparably from creatinine indicators.
The term «uremia» is used when the level of urea in the blood rises above 20 mmol / l. Azotemia, the indicator of which also serves as an increase in the concentration of urea, is most often the result of inadequate excretion due to kidney disease.
The level of urea in the blood decreases in many liver diseases. This happens due to the inability of damaged liver cells to synthesize urea, which, in turn, leads to an increase in the concentration of ammonia in the blood and the development of hepatic encephalopathy.
Renal failure manifests itself when the glomerulus loses its ability to filter blood metabolites through itself. It can happen suddenly (acute kidney failure) in response to disease, medication, poison, injury. Sometimes it is a consequence of chronic kidney diseases (pyelonephritis, glomerulonephritis, amyloidosis, kidney tumors, etc.) and other organs (diabetes, hypertension, etc.). A urea test is usually prescribed in combination with a blood creatinine test.