BLOOD UREA NITROGEN (BUN)

• Why Take this Test

  Blood Urea Nitrogen is a very common test that indicates how well are your kidneys performing in their ability to filter urea from the blood. It is also used to help determine the effectiveness of dialysis treatment if you're receiving haemodialysis (artificial kidneys used to filter blood in cases when natural kidneys have failed) to see if the dialysis is working properly and the artificial kidney is able to clean the blood performing work of the natural kidney. The test is often a part of the routine health check-up and helps diagnose number of other conditions, such as liver damage, urinary tract obstruction, congestive heart failure or gastrointestinal bleeding — although an abnormal BUN is not specifically associated with any of these conditions.

  BUN is often ordered with other kidney related test such as creatinine when kidney problems are suspected.

• Is this Test For You

  Some signs and symptoms of kidney dysfunction include Fatigue, poor appetite, or disturbed sleep, swelling or puffiness (edema), particularly near the eyes or on the face, wrists, abdomen, thighs, or ankles, unusually textured or coloured urine, a decrease in urine output, burning or abnormal discharge during urine, and increased frequency. This entire spectrum of conditions can indicate a kidney disorder and needs further testing.

• More Information

  During digestion of proteins, our liver produces ammonia as a by-product. This ammonia further gets converted into urea and gets released into the blood. Since urea is a toxic substance, our body eliminates it from the blood, by the kidneys; as this blood enters the kidneys they filter them out and urea gets eliminated in the urine. If unusually high concentration of urea is present in the blood, it indicates something wrong with the kidney, and is associated with the inability of the kidney to filter out blood. Thus, urea is measured in terms of “Blood Urea Nitrogen”

  Increased BUN levels suggest abnormal functioning or a dysfunction of the kidney. This may be because of acute or chronic kidney disorder, damage, or failure. It may also be due to conditions when kidneys are properly functioning, but certain conditions persist that blunt the blood flow towards the kidneys due to which the waste products are not being filtered normally. Such conditions include congestive heart failure, shock, stress, recent heart attack, or severe burns, to conditions that cause obstruction of urine flow, or to dehydration.

  BUN concentrations could also be elevated when there's excessive protein breakdown (catabolism), significantly increased protein within the diet, or gastrointestinal bleeding (because of the proteins present within the blood).

  If one kidney is fully functional, BUN concentrations may be normal even though the other kidney is non-functional.

Sample: Serum (2 mL)

Methodology: Calculated