Urea nitrogen (BUN) liquid reagent is used for the kinetic quantitative determination of Urea Nitrogen (BUN) in human serum used in routine examination and monitoring of therapy and relapses. Urea is the principle waste product of protein catabolism. It is synthesized in the liver from ammonia which is produced as a result of the deamination of amino acids. Normally, urea nitrogen in the blood comprises only about 45% of the non-protein nitrogen. The importance of urea nitrogen determination is its value as an indicator of liver and kidney functions. Decreases in Blood Urea Nitrogen (BUN) are seen with nephritis, acute liver destruction, amyloidosis and pregnancy.1 Increases in BUN are encountered with acute and chronic nephritis, intestinal and urinary obstruction, uremia, metallic poisoning, pneumonia, Addison's disease, peritonitis, surgical shock and cardiac failure.