Blood Urea Nitrogen (BUN)

Blood urea nitrogen Is nitrogen, which is included in the final products of protein metabolism, in particular, urea. It makes up about half of the residual nitrogen in the serum.

After the proteins used by the cells are broken down, the liver produces them Ammonia - which contains nitrogen. Nitrogen in ammonia binds to other elements such as carbon, hydrogen, and oxygen to form Urea, which is a chemical waste product. Urea travels from the liver to the kidneys through the bloodstream. Healthy kidneys filter it and eliminate it from the blood through the urine, along with other waste products.

Blood Urea Nitrogen (BUN) The test gives us important information about how well the kidneys are functioning.

This rate is directly related to the concentration of urea in the blood, its concentration does not exceed the normal range until the glomerular filtration rate falls below 40 ml / min (less than 50% of normal value).

When to take a blood urea nitrogen (BUN) test?

• Diagnosis of renal failure;
• Differentiation of prerenal and postrenal azotemia according to urea / creatinine ratio.
• Monitoring of end-stage renal disease;
• Monitoring of hemodialysis;
• Monitoring the effectiveness of a low-fat diet in chronic kidney disease.

How to prepare for the test?

No special preparation is required for the test.

The test should be performed on an empty stomach.

Research material

Venous blood

Possible interpretation of the results

University Library Concentration increases:

1. Prerenal causes:

• Dehydration (shock, heavy bleeding, severe diarrhea, profuse vomiting);
• Pathology of the cardiovascular system.

2. Renal causes:

• Acute and chronic glomerulonephritis;
• Chronic pyelonephritis;
• Nephrosclerosis caused by poisoning with mercury salts, glycols, dichloroethane and other toxic substances;
• CRUSH syndrome (increased protein breakdown);
• Diabetic nephropathy;
• Gout;
• Hydronephrosis, severe polycystic ovary syndrome, renal tuberculosis;
• Amyloid or amyloid-lipoid nephrosis (late stage of the disease).

3. Postrenal causes:

• Urinary tract obstruction

University Library Concentration decreases:

• Low-carbohydrate diet;
• Hepatic dysfunction (hepatic coma, cirrhosis of the liver, hepatitis, etc.);
• Poisoning with phosphorus, arsenic;
• Malabsorption syndrome, malnutrition;
• Hyperhydration;
• Acromegaly (increased use of protein for synthesis);
• Taking anabolic hormones;
• Disorder of antidiuretic hormone secretion syndrome;
• Hereditary hyperamemia;
• Age of children;
• Pregnancy (3-4th trimester with development of physiological hypervolemia)

Resources

https://spravochnik.synevo.ua/ru/klinicheskaia-himia/azot-mochevini.html

https://www.mayoclinic.org/tests-procedures/blood-urea-nitrogen/about/pac-20384821