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Quantitative determination of Urea (Berthelot Method). Urea is the end product of protein metabolism.It is produced in the liver and eliminated from the blood in kidneys. Estimation of Urea with creatinine allows assessment of kidney function. Principle of the method.
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Urea is the end product of protein metabolism.It is produced in the liver and eliminated from the blood in kidneys. Estimation of Urea with creatinine allows assessment of kidney function.
Principle of the method • Urea is hydrolyzed by urease into ammonia and carbon dioxide. • The ammonia generated reacts with alkaline hypochlorite and sodium salicylate in presence of sodium nitroprusside as coupling agent to yield a green cromophore. • The intensity of the color formed is proportional to the concentration of urea in the sample. 1. Urea + H2O2 NH3 + CO2 2. NH4 + + Salycilate + NaClO Indophenol + NaCl Urease
Clinical significance • Elevated levels od blood urea reflect some alteration of the excretory function of the kidney.The increase may also be due to the poor liver function,cardiac failure or diet itself. • Dehydration and bleeding can raise levels of blood urea Sample Serum or plasma
Calculations • SA Abs /ST Abs x 40 = mg Urea /dl SA Abs: Sample Absorbance ST Abs: Standard Absorbance Reference values • Serum,plasma: 15-45 mg/dl • Urine:20-35 g/L