Urea | Laboratory research

SKU 1060 Category Tag

Additional information

Response time (working day) | Time to results


Location of analysis | Where is performed



Urea Is the end product of protein metabolism in the body. The major site of urea production is the liver, however, tissue during growth (e.g., embryonic tissue or tumor tissue) tends to produce urea from arginine.

Most of the urea is excreted by glomerular filtration; 40-60% is reabsorbed into the blood, depending on the rate of flow in the tubules and the concentration of antidiuretic hormone (ADH).

Changes in urea concentration in the blood and urine are directly proportional to the protein diet and inversely proportional to the increase in cell anabolism, pregnancy, and recovery.

In addition, the concentration of urea in plasma depends on its absorption by the kidneys: with adequate diuresis, urea uptake into the blood from the distal tubules is reduced to a minimum, large amounts of urea are excreted in the urine, and serum urea levels remain low; If there is a decrease in diuresis, such as oliguria in thirst, excitability, heart failure, urea is reabsorbed from the distal tubules into the blood, and plasma urea levels increase.

Persistently elevated levels of serum urea indicate significant changes in glomerular filtration rate. With normal protein intake (100 g per day) and normal renal absorption, no increase in serum urea is observed until the glomerular filtration rate is reduced to 30 ml / min.

In pronounced renal insufficiency, serum urea concentration correlates with glomerular filtration rate. In chronic renal failure with polyuria or vomiting, accompanying diarrhea, liver failure, urea levels may not rise more than predicted. On the other hand, in chronic renal failure with oliguria, increased protein intake, heart failure, gastrointestinal bleeding, urea levels may be higher than expected.

When to take a urea test?

Urea is one of the indicators of impaired nitrogen metabolism.

  • Renal and hepatic impairment (renal and hepatic insufficiency);
  • Differentiation between prerenal and postrenal azotemia according to urea / creatinine ratio;
  • Monitoring the effectiveness of a low-fat diet in chronic renal failure;
  • Hemodialysis monitoring.

How should we prepare for the test?

Fasting is recommended for the test.

Research material

Venous blood

Possible interpretation of the results

Urea concentration increases:

  • Decreased renal perfusion due to congestive heart failure, gastrointestinal bleeding, shock, dehydration;
  • Acute / chronic glomerulonephritis, pyelonephritis;
  • Genitourinary obstruction, amyloidosis, renal tuberculosis;
  • Increased protein catabolism: burns, cancer, prolonged fever, stress;
  • Diabetes mellitus with ketoacidosis;
  • Decreased concentration of chlorine in the blood;
  • Increased protein intake.

Urea concentration decreases:

  • Severe liver diseases: acute, chronic, toxic hepatitis, cirrhosis, liver coma;
  • Excessive hydration (including excessive intravenous fluid administration);
  • Malabsorption, malnutrition;
  • Acromegaly;
  • ADH inadequate secretion syndrome;
  • Hereditary hyperamemia;
  • Condition after dialysis;
  • In children;
  • Pregnancy (3-4th trimester - physiological hypervolemia).



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