Blood urea determination

Rovida E, Mosca A, Dossi G. Serum and whole blood urea determination by the use of a microprocessor controlled differential pH analyzer. Eur J Chn Chem Chn Biochem 1981 19 820. 

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. 

The ICH S7A states that the effects of the NCE on renal parameters should be assessed for example, urinary volume, specific gravity, osmolality, pH value, fluid/electrolyte balance, proteins, cytology, and blood chemistry determinations such as blood urea... 

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. 

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. 

Clinicians rely mainly on blood urea nitrogen (BUN) and serum creatinine measurements to evaluate patients with renal failure. Yet the correlation between symptoms and blood levels is at best approximate. In acute renal failure the underlying disease and its associated complications often dominate the clinical picture and determine the prognosis, and it is unclear at what level of nitrogen retention symptoms may be attributed to uremia. Clinicians generally institute dialysis when the BUN exceeds 100 mg/dl or the serum creatinine exceeds 10 mg/dl, but sometimes earlier or later, and early dialysis has not been shown to confer distinct benefits. In chronic renal failure, patients may be quite asymptomatic despite very high BUN and serum creatinine levels. Many so called uremic symptoms may be more properly attributed to anemia, heart failure, nephrotic edema and hypoproteinemia, hypertension, malnutrition, or uncontrolled diabetes or its complications, such as gastroparesis, diarrhea, and neuropathy. 

No adverse effect on liver weight was observed in female ICR mice treated by gavage with 400 mg/kg petroleum creosote in DMSO on gestational days 5-9 (Iyer et al. 1993). In a feed study of MGP coal tar by Weyand et al. (1994), B6C3Fj mice were exposed to 0, 51, 251, or 462 mg/kg/day (males) and 0, 42, 196, or 344 mg/kg/day (females) in the feed for 94 or 185 days. Plasma clinical chemistry parameters determined were as follows glucose, creatine, blood urea nitrogen, total protein, ALT, ALT, and alkaline phosphatase activity. Tissues obtained from the animals were examined for microscopic lesions. There was no adverse effect of treatment on liver histopathology or serum enzymes. 

You are developing a new analytical method for the detemaination of blood urea nitrogen (BUN). You want to determine whether your method differs significantly from a standard one for analyzing a range of sample concentrations expected to be found in the routine laboratory. It has been ascertained that the two methods have comparable precisions. Following are two sets of results for a number of individual samples. 

Blood glucose and blood urea nitrogen (BUN) are probably the two most frequently performed clinical tests. In the procedures described in Table 24.2, the total of all reducing sugars is measured, and so results tend to be high. But these methods have been adopted as standard ones for many years. The enzymatic determination of glucose (Chapter 22) is an established method, and dedicated enzymatic glucose analyzers are now widely used. 

Given the following information about five newborn infants (identified as I to V) who appeared normal at birth but developed hyperammonemia after 24 hours, determine which urea cycle enzyme might be defective in each case (for each infant, choose from the same five answers, lettered A through E). All infants had low levels of blood urea nitrogen (BUN). (Normal citrulline levels are 10-20 p,M.)... 

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