urea nitrogen

urea (u-re´ah)

1. the chief nitrogenous endproduct of protein metabolism, formed in the liver from amino acids and from ammonia compounds; found in urine, blood, and lymph.

2. a pharmaceutical preparation of urea used to lower intracranial or intraocular pressure, to induce abortion, and as a topical skin moisturizer.ure´al

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urea nitrogen  the urea concentration of serum or plasma, conventionally specified in terms of nitrogen content and called blood urea nitrogen (BUN); an important indicator of renal function.

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urea nitrogen

n.

The concentration of nitrogen in blood or urine, for example, derived from urea.

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urea nitrogen.

See blood urea nitrogen.

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urea [u-re´ah]

1. the diamide of carbonic acid found in urine, blood, and lymph, the chief nitrogenous constituent of urine, and the chief nitrogenous end-product of protein metabolism; it is formed in the liver from amino acids and from ammonia compounds.

2. a pharmaceutical preparation of this compound, administered intravenously as an osmotic diuretic to lower intracranial or intraocular pressure, injected transabdominally into the amniotic sac to induce abortion of a second trimester pregnancy, and included in topical preparations to moisten and soften rough, dry skin.



The amount of urea in the urine increases with the quantity of protein in the diet because urea is an endogenous and exogenous waste product: endogenous because some of it is derived from breakdown of body protein as tissues undergo disintegration and repair, and exogenous because some of it is derived from the deamination of amino acids absorbed from the intestinal tract but not utilized by the body. In severe nephritis or other disorders leading to renal failure, the concentration of urea in the blood may be greatly increased, as revealed by measurement of the blood urea nitrogen (BUN).

urea concentration test a test of renal efficiency, based on the fact that urea is absorbed rapidly from the stomach into the blood and is excreted unaltered by the kidneys; 15g of urea is given with 100mL of fluid, and the urine collected after 2 hours is tested for urea concentration.

urea nitrogen the urea concentration of serum or plasma, conventionally specified in terms of nitrogen content and called blood urea nitrogen (BUN), an important indicator of renal function.

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urea

1. the diamide of carbonic acid found in urine, blood and lymph, the chief nitrogenous constituent of urine, and the chief nitrogenous end product of protein metabolism; it is formed in the liver from amino acids and from ammonia compounds.

2. a pharmaceutical preparation of urea occasionally used to lower intracranial pressure.

3. industrial urea is used as a fertilizer and feed additive for ruminants. Overfeeding or accidental access to large amounts can cause fatal poisoning.

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urea cycle

see urea cycle.

urea cycle enzyme deficiency

see arginosuccinate synthetase, citrullinemia.

urea hydrogen peroxide

see carbamide peroxide.

urea nitrogen

the urea concentration of serum or plasma, conventionally specified in terms of nitrogen content and called blood urea nitrogen (BUN), an important indicator of renal function.

urea poisoning

causes tremor, dyspnea, abdominal pain, incoordination, bellowing, convulsions and death in 2 to 4 hours. Due to hyperammonemia.

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urea nitrogen

See BUN.