45 



PHYSIOLOGICAL CHEMISTRY 



surface tension method. Urines preserved with thymol may respond positively 

 to this test. 



CH 3 



I 

 ACETONE, C = O. 



CH 3 



It was formerly very generally believed that acetone appeared in the 

 urine under pathological conditions because of increased protein de- 

 composition. It is now generally thought that, in man, the output 

 of acetone arises principally from the breaking down of fatty tissues 

 or fatty foods within the organism. The quantity of acetone elimi- 

 nated has been shown to increase when the subject is fed an abundance 

 of fat-containing food as well as during fasting, whereas a replace- 

 ment of the fat with carbohydrates is followed by a marked decrease 

 in the acetone excretion. If no carbohydrate food is fed the output of 

 acetone bodies increases at once, producing a physiological acidosis 

 j^jQiafrt^^ . 



Acetone and the closely related bodies, /3-hydroxybutyric acid and 

 acetoacetic acid, are generally classified as the acetone bodies. They 

 are all associated with a deranged metabolic function and may appear 

 in the urine together or separately, depending upon the conditions. 

 Acetone and diacetic acid may occur alone in the urine but /3-hy- 

 droxybutyric acid is never found except in conjunction with one or the 

 other of these bodies. Both acetone and /3-hydroxybutyric acid may 

 be formed from acetoacetic acid. The relation existing between these 

 three bodies is as follows: 1 



CH 3 CO.CH 2 .COOH->CH 3 CO.CH 3 +C0 2 . 



Acetoacetic acid. Acetone. 



H (reduction) 



CH 3 CHOH.CH 2 COOH. 



/3-hydroxybutyric acid. 



Acetone, chemically considered, is a ketone, di-methyl ketone. When 

 pure it is a liquid which possesses a characteristic aromatic fruit-like 

 odor, boils at 56-57C. and is miscible with water, alcohol, or ether 

 in all proportions. Acetone is a physiological as well as a pathological 

 constituent of the urine and under normal conditions the daily output 

 (preformed acetone + acetoacetic acid) is about 3-15 mg. 



1 Maase: Med. Klinik, 61, 445, 1910. 

 Blum: Munch, med. Woch., 57, 683, 1910. 

 Dakin: Jour. Biol. Chem., 8, 97, 1910. 

 Marriott: Jour. Biol. Chem., 18, 241, 1914. 

 Mathews: Physiological Chemistry, 26. Ed., 1916, p. 756. 

 Allen: Am. Jour. Med. Sci., 153, 313, 1917. 



