Blood Urea Nitrogen (BUN)

Urea chemically comprises of nitrogen (N), carbon (C), hydrogen (H) and oxygen (O2).

It is a waste product of protein catabolism and is removed from the blood through the kidneys. Nitrogen is removed

from the body in the form of ammonia (NH4) in the context of aquatic animals and in the form of urea and uric acid in the land animals.

Liver malfunction leads in reduced amount blood urea. It is a waste product that is re-absorbed by the medullary region of the kidneys. It is mixed in the blood and eliminated in the urine at a concentration of 2.5 to 7.5 m mol/l. Aves and reptiles eradicate uric acid, while mammals and others emit urea. It is consumed to decrease volume.

Minute quantities of urea are removed by sweat. Urea chemically is a fertilizer and consumed in many plant augmentation preparations.

The quantity of nitrogen in the urea is estimated by blood urea nitrogen (BUN). Urea nitrogen in the blood is a sign of renal

functioning, though changes in the blood urea nitrogen (BUN) levels are seen in hepatic failure and catabolism of proteins. The adult BUN levels range from 7 to 20 mg/dl with the values growing in senescence. The BUN values decreases by 25 percent during pregnancy. The newborn infants have a lower level than adults.

A decrease in blood urea nitrogen levels occur in the case of:-

Malnourishment
Hepatic failure
Nutrient mal-absorption
Pregnancy
Consumption of anabolic steroids
Over hydration.

In the case of an individual suffering from "syndrome of inappropriate anti-diuretic secretion" (SIADH), the ADH or the anti-diuretic hormone triggers the kidney to save water results in retention of unnecessary water in the blood stream. This results in low BUN i.e. blood urea nitrogen levels and other vital substances, as the fluid capacity of blood raises. The normal range for BUN values are 7 to 20 mg/dl. This test is conducted to evaluate the kidney functioning capacity and treatment given and the presence of dehydration.

Blood urea nitrogen is assessed with creatinine test. Serum creatinine proves useful in diagnosing renal failure and diseases. A directly proportional relationship exists amid creatinine levels and renal function. Both the blood urea nitrogen (BUN) and creatinine levels are helpful in achieving the BUN to creatinine ratio. This test is a diagnostic tool in recognizing the causative factor for abnormal levels, such as de-hydration, as its consequences in higher BUN to creatinine ratio. This is credited to the fact that BUN levels are more than creatinine levels, during dehydration. Both BUN and creatinine levels are increased in the case of kidney malfunctioning or urinary flow damage.