Use of a Screening Procedure for Blood Urea Nitrogen.

CONSTANT PROBLEM lli the hospital climiical laboratory is the emergency order which arrives with great regularity after the routine mu of a particular analysis has been finished. With automatiomi the problem has increased, particularly in laboratories where one automatic instrument is used for several different procedures in turii. There are three possible solutions. One is to perforni the test mimanuahly. This requires, gemierally, a second set of standards, comitrol, and reagents, and a more-or-less different method for each type of assay from thiat usually perfornied autoIiiatiCally. Furthermore, these simigle deteriiiinatiomms are highly unpopular with the teehimuical personmiel, who as a consequence often resort to the secOnd solution, which is to reset the automatic instrumentation to run this single determimiatiomi. This is uneconomical for the laboratory with regard to both time and money. The third solution lies in the fact that frequently an absolute answer is not immediately required and the physician is satisfied with knowing at time moment whether the determination on the patient’s specimen is iiornial or abnormal, and receivimig the actual value the next day. For this purpose a screenimig test which can differentiate time normal from the abmioi’mal with accuracy, requires little or no reagent preparatiomi amid only a few minutes of technologists’ time is very convenient. This report describes the use of such a test for 1)100(1 urea nitrogeni.* In 1959 Appleton et al. (1) described the use of this strip test as a simmvey procedure to separate specimens with normal urea nitrogen levels from those with abnormal levels, and in a large series they reported ‘‘an overall error of ± 10% from the actual analytic values.” Tn 1960 Martin