Urea nitrogen, determination

Bandi, Z.L., Fuller, J.B., Bee, D.E. and James, G.P. (1981). Extended clinical trial and evaluation of urea nitrogen determination with the Ektachem GLU/ BUN analyzer. Clin. Chem. 27, 480-485. 

E245 Burdick, B.A. (1986). A dry-reagent thin-film element for urea nitrogen determination in whole blood. Clin. Chem. 32, 1195, Abstr. 724. 

Recently, the old alkaline phenol method has been revived, and is being widely used in clinical laboratories, without protein preclpltatlon(27). In this procedure, the serum is added to an alkaline phenol reagent, and the ammonia generated from urea is determined either after the action of urease or after strong alkaline treatment of the serum. The objection to this procedure is first, that all urease is rich in ammonia, and second, the color produced with alkaline phenol is not specific for ammonia. It will react with other compounds, especially for those that liberate ammonia. By this procedure one obtains a useful number from the point of view of determining whether the patient has nitrogen retention, but a value which is somewhere between a urea and an N.P.N. determination. 

Patients should have blood urea nitrogen, serum creatinine, aspartate transaminase or alanine transaminase, and a complete blood count determined at baseline and periodically, depending on the presence of other factors that may increase the likelihood of toxicity (advanced age, alcohol abuse, and possibly pregnancy). Hepatotoxicity should be suspected in patients whose transaminases exceed five times the upper limit of normal or whose total bilirubin exceeds 3 mg/dL. At this point, the offending agent(s) should be discontinued, and alternatives selected. 

Experimental design Rats (7-13 male and 10-13 female) were exposed to 1,4-dichlorobenzene vapors for 7 hours a day, 5 days a week at concentrations of 0, 96, or 158 ppm for a total of 126-139 exposures. At the end of the exposure period, the animals were sacrificed, body and organ weights determined, and tissues examined microscopically. Hematology (parameters not specified), analysis of urine (blood, glucose, albumin, and sediment) and measurement of blood urea nitrogen were conducted for females exposed to the lowest concentration of 1,4-dichlorobenzene. 

Urea Nitrogen Macro and Micro. The flow diagram of the urea nitrogen method is shown in Fig. 18. The method originally used for citrulline (FI) has been adapted to the determination of urea (Ol). Although the method has had limited success in routine clinical chem-... 

Ml. Marsh, W. H., Fingerhut, B., and Kirsch, E., Determination of urea nitrogen with the diacetyl method and an automatic dialyzing apparatus. Am.. Clin. Pathol. 28, 681-688 (1957). 

Urea is most commonly assayed by combined urease methods, in which the urea is first converted to two ammonium ions. The ammonium generated is then measured by either enzymatic or chemical methods. Urea nitrogen values determined by this method (mg/ml) are converted to urea values by the use of appropriate factors (2.14 for urea in mg/ml, 0.357 for urea in mmol/L) (Emeigh Hart and Kinter 2005). 

Williams et al. (1997) described renal ischemia-reperfusion injury in rats. The animals were anesthetized and subjected to 45min of bilateral renal occlusion using atraumatic vascular clamps before renal perfusion was reestablished. After various time interval (up to lweek) blood urea nitrogen, creatinine and myeloperoxidase activity in the kidney were determined. The protective effects of an intracellular adhesion molecule monoclonal antibody were tested. 

Based on the A340 of your plasma sample and the volume of the plasma sample used in the assay, determine the concentration of urea nitrogen in your plasma sample. 

Martinek, R. G. (1969). Review of Methods for Determining Urea Nitrogen in Biological Fluids. J Am Med Technol 31 678. 

Urastrat a complete quantitative system for the determination of urea nitrogen in serum Marketed by General Diagnostics, Warner-Lambert (UK) Ltd, Eastleigh, Hampshire, UK... 

Freeze-dried serum provides no advantage over serum frozen at -30°C in the determination of species such as glucose, urea, nitrogen, sodium, potassium, total protein and... 

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