urea

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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.

u·re·a

(yū-rē'ă),
The chief end product of nitrogen metabolism in mammals, formed in the liver by means of the Krebs-Henseleit cycle and excreted in normal adult human urine in the amount of about 32 g a day (about 85% of the nitrogen excreted from the body). It may be obtained artificially by heating a solution of ammonium cyanate. It occurs as colorless or white prismatic crystals, without odor but with a cooling saline taste, is soluble in water, and forms salts with acids; has been used as a diuretic in kidney function tests, and topically for various dermatitides.
[G. ouron, urine]

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

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

(yo͝o-rē′ə)
n.
A water-soluble compound, CO(NH2)2, that is the major nitrogenous end product of protein metabolism and is the chief nitrogenous component of the urine in mammals and certain other animals. Also called carbamide.

urea

[yoo͡r′ē·ə]
Etymology: Gk, ouron, urine
a normal metabolic waste product from protein metabolism, used as a systemic osmotic diuretic and topical emollient.
indications It is prescribed systemically to reduce cerebrospinal and intraocular fluid pressure and is used topically as a keratolytic agent.
contraindications Severely impaired kidney function, active intracranial bleeding, marked dehydration, or liver damage prohibits its systemic use.
adverse effects Among the more serious adverse effects are pain and necrosis at the site of injection, headache, GI disturbances, and dizziness. There are no known severe reactions to topical use.

u·re·a

(yūr-ē'ă)
The chief end product of nitrogen metabolism in mammals, formed in the liver, by means of the Krebs-Henseleit cycle, and excreted in normal adult human urine in the amount of about 32 g a day (about 89% of the nitrogen excreted from the body); used as a diuretic in kidney function tests and topically for various dermatitides.
[G. ouron, urine]

urea

A substance formed in the liver from the excess of nitrogenous material derived from amino acids and excreted in solution in the urine. Urea can be used as an osmotic diuretic and as a cream for ICTHYOSIS and other hyperkeratotic skin disorders. The drug is on the WHO official list. See also URAEMIA.

urea

an organic molecule that forms the major end product of protein metabolism in mammals, being derived mainly from the ammonia released by the deamination of AMINO ACIDS. Formula: CO(NH2 )2. see ORNITHINE CYCLE.

Urea

A by-product of protein metabolism that is formed in the liver. Because urea contains ammonia, which is toxic to the body, it must be quickly filtered from the blood by the kidneys and excreted in the urine.

urea

soluble endproduct of nitrogen metabolism; acts as skin hydrating agent when incorporated into emollient creams, e.g. 10% urea creams

hyperosmotic agent

A drug that makes blood plasma hypertonic thus drawing fluid out of the eye and leading to a reduction in intraocular pressure. It is used in solution in the treatment of angle-closure glaucoma and sometimes before surgery to decrease the intraocular pressure. Common agents include glycerin (glycerol), isosorbide, mannitol and urea. See hypertonic solution.

u·re·a

(yūr-ē'ă)
Chief end product of nitrogen metabolism in mammals.
[G. ouron, urine]

urea (ūrē´ə),

n a water-soluble compound that is the primary constituent of urine.
Ureaplasma
n gram-negative eubacteria from the family Mycoplasmataceae that serve as a hydrolitic for urea. The bacteria do not have cell walls.

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.

urea cycle
see urea cycle.
urea cycle enzyme deficiency
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.