Studies of the Urea Content of Capillary and Venous Blood

Publisher Website
Google Scholar
Abstract
The micro-method of Rehberg was used. 0.5 cc. of distilled water is placed in a test-tube and 0.1 cc. blood, measured in a Hagedorn pipette, is added. Then 0.1 cc. of a fresh 10% urease solution (Squibb), adjusted to [rho]H 7 with a phosphate buffer solution, is added. The tube, closed with a rubber plug, is placed on the water-bath at 40[degree] for 30 min. Then 3 drops of octyl alcohol and 1 cc. saturated K2CO3 solution are added. Previously however, 2 cc. n/600 H2SO4, freshly prepared from n/10 H2SO4, should be measured into each titration tube, 1 drop of octyl alcohol being added. The test tubes and titration tubes are then connected, and aeration takes place for 2.5 hrs. Blank anaylses are set up and a control with a known urea solution (a 60 mg.% urea solution was used). When aeration is completed the solution is titrated with n/30 NaOH by Rehberg''s microburette. Methylene red as indicator was used in a 0.05% solution. The mean error was 1 mg urea. 27 out of 32 sets of analyses of blood from 18 fasting normal individuals showed on the average concentration of urea 10 % higher in capillary blood than in venous blood. Percentage differences of 4-22 were found. The absolute difference was 3 mg. on an average. In 4 cases the values were slightly higher for venous blood, in a single case as much as 20% higher. Following the ingestion of protein, urea, diet poor in protein, fat + starch, and glucose, the rule was again a higher concentration of urea in capillary than in venous blood.Examination of patients with diabetes, nephritis and icterus showed similar relations to those observed in normals. Only in 2 out of 22 cases was the urea content higher in venous blood.

This publication has 1 reference indexed in Scilit: