248 PHYSIOLOGICAL CHEMISTRY 



Uric acid is present in normal blood to the extent of about 1-2 mg. 

 per 100 grams of blood. In gout this value may be increased to 4-6 

 mg. The quantitative determination of the uric acid content of blood 

 is of importance as an aid in differentiating gout and certain other 

 disorders exhibiting similar clinical symptoms (for method see page 

 274). 



The non-protein nitrogen of normal blood amounts to about 25-35 

 mg. per 100 grams of blood. The urea forms about 50 per cent of this, 

 creatinine 2 per cent, uric acid 2 per cent, ammonia 0.3 per cent, and 

 amino-acids, etc., about 46 per cent. In nephritis the non-protein 

 nitrogen of the blood is much increased. Myers and Fine 1 report a 

 fatal case of uremia in which the non-protein nitrogen reached 300 mg. 



Amino-acids are always present in the blood. They result for the 

 most part from the digestion of protein material in the intestine. 



Creatinine occurs in normal blood to the extent of about 1-2 mg. 

 per 100 c.c. of blood. In uremia the amount is increased. 2 Various 

 investigators report the values as ranging from 5 to 33 mg. per 

 100 c.c. 



The creatine content of normal blood ranges from 5 to 10 mg. per 

 100 c.c. of blood. The creatine values have no important pathological 

 significance at the present time. 



The acetone (acetone and acetoacetic acid) content of normal blood 

 ranges from o to i mg. per 100 c.c. of blood. In mild diabetes mellitus 

 the value rises to 5-12 mg., whereas in severe diabetes mellitus (coma) 

 as much as 20-45 m g- P er I0 c - c - f blood serum has been found. 



Normal blood contains about 20 per cent of solids and 3 per cent of 

 total nitrogen, whereas chlorides are present to the extent of about 0.65 

 per cent. In severe diabetes the chlorides are decreased because of the 

 accompanying diuresis. 



Abel 3 and associates have devised a method by which diffusible 

 substances may be removed from the blood of a living animal. The 

 process is termed mvidifusion and is brought about by permitting the 

 blood from an artery to flow through collodion tubes surrounded by 

 physiological salt solution. The dialyzable substances, except sodium 

 chloride, are removed and the dialyzed blood is returned to the body of 

 the animal by means of a vein. The apparatus has been modified by 

 McGuigan and von Hess. 4 



1 Myers and Fine: Chemical Composition of the Blood in Health and Disease, 1915. 



2 Folin and Denis; Jour. Biol. Chem., 17, 487, 1914. 

 Myers and Fine: Jour. Biol. Chem., 20, 391, 1915. 



3 Abel, Rowntree and Turner: Transactions of the Ass'n of American Physicians, 1913; 

 also Jour, of P harm, and Exp. Therap., 5, 275, 1914. 



4 McGuigan and Von Hess: Jour. Pharm. and Exp. Therap., vol. 6, 1914. 



