The Amino-acid Content of the Blood in Normal and Pathologic Conditions

The present day concepts of the amino-acid metabolism in normal persons have been formulated largely on the basis of the studies of Folin and Denis, Van Slyke and Meyer, and Folin and Berglund. These authors have been particularly interested in the relation of the amino-acids in the blood to the processes of protein metabolism in normal persons. The behavior of the amino-acids in the blood in disease has not been investigated so thoroughly. On the basis of his study of normal persons, Folin says: “The deamination process appears to be such a fundamental process that one cannot expect to find many pathological conditions in which the amino nitrogen of the blood filtrates will vary very much from the normal.” Various analyses of the blood in disease have been reported, but not in a series sufficiently large to establish this generalization. Furthermore, the results reported have not been sticiently uniform to be of great value in the study of the deamination process. The quantitative study of the amino-acids in the blood has been difficult because of the inadequacy of the earlier methods of analysis; indeed it was not until 1914 that Abel, Rowntree, and Turner first isolated crystalline amino-acids from the blood stream by their method of vividiffusion. The present methods of analysis are more satisfactory, but the exact amount of amino nitrogen found in a sample of blood depends largely on the details of the analytic method used. Amino-acids are more concentrated in the blood corpuscles than in the serum.