The Blood Uric Acid in Disease.

Because of the large number of patients in the University of Chicago Clinics showing high blood uric acid by the Koch I modification of the Folin and Benedict methods using the Folin-Wu blood filtrate, it was decided to try a different method. The method which has seemed to to yield most satisfactory results is that described by Folin (1) in which he makes use of unlaked blood filtrate, a cyanide solution stabilized by means of urea, and a uric acid reagent free from phenol reagent. This method has been used for all uric acid determinations in the Medical department since May 1931, and has proved relatively satisfactory as a clinical method. The cyanide solution, which is kept at low temperature, retains its chromophoric power well, and when used with the uric acid reagent has produced no turbid solutions. It was, of course, necessary to determine a new series of normal blood uric acid values by this method, and while the results are not wholly free from unexplained high values (see Table V), it is believed that this method, as compared with the one formerly used, gives more satisfactory results. For the purpose of comparison a few samples of blood were tested simultaneously for uric acid by the Koch modification formerly used (hereafter called " old method ") and by the Folin method at present used. Two samples from a control patient, drawn on different days, gave 7.2 and 9.2 mgm. per 100 cc. by the old method and 3.9 and 3.8 mgm. per 100 cc. respectively by the new method. One sample from a patient with chronic gout gave 12.3 and 5.6 mgm. per 100 cc. by the old and new methods respectively. The uric acid in the blood of a patient with infectious arthritis was 5.3 and 2.1 mgm. per 100 cc. by the old and new methods respectively. There was thus a deviation in all instances in the same direction and to about the same degree, but there also seemed to be less variation in the results given by the method at present in use. The first and most important consideration for diagnostic purposes in adopting a new method of determining the amount of uric acid in the venous blood was to find an upper limit for normal which would be reasonably satisfactory. In Table I are a number of uric acid determinations made on diseasefree controls. It will be seen that in only two, Case 6, W. C., and Case