A quick, accurate test for determining the serum urea nitrogen level is needed for night and emergency work and for routine office screening. Caraway1 describes a rapid turbidity method for determination of urea nitrogen level with use of xanthydrol. We find his method to be only semiquantitive; it is able to determine whether the urea nitrogen level is normal or above normal but does not measure satisfactorily the degree of elevation. Also, the timing is extremely critical. The urea nitrogen test described here is performed on a drop of serum or plasma and is accurate enough for routine clinical needs over the range of 4 to 300 mg. per 100 cc. It uses a minimum of equipment and stable reagents and is a simple, twominute test.
Principle of Method
The method proposed here is a modification of the method of Van Slyke and Cope.2 One drop of glycerin
Lile EC, Villamil MF, Rhees MC, Scribner BH. BEDSIDE DETERMINATION OF UREA NITROGEN LEVEL IN SERUM OR PLASMA. JAMA. 1957;164(3):277–279. doi:10.1001/jama.1957.62980030001013
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