URINE 535 



these conditions, being used in the neutralization of the excess acids 

 formed in the body. Usually about three-quarters of the combined 

 acetone and acetoacetic acid excretion is in the form of acetoacetic acid, 

 but the proportion is not constant. 



Acidosis is due mainly to a disturbance in the metabolism of fats. 

 The fatty acids are ordinarily oxidized through hydroxybutyric acid to 

 acetoacetic acid which is in turn oxidized through formic and acetic 

 acids to carbon dioxide and water. When fat catabolism is increased 

 to such an extent that the body cannot bring about complete oxidation 

 of the products formed, a considerable portion of the acetoacetic acid 

 instead of being oxidized in this way is transformed into acetone 

 (a process taking place but to a slight extent normally) . This acetone 

 as well as acetoacetic acid and in more severe cases /3-hydroxybutyric 

 acid will then be eliminated to varying degrees in the urine. 



The relation of the acetone bodies is indicated in the following 

 scheme: 



CH 3 CHOH CH 2 COOH (/3-hydroxybutyric acid) 



oxidation I J reduction 



CH 3 CO CH 2 COOH (acetoacetic acid) 



| loss of CO 2 



CH 3 CO CH 3 (acetone) 



In fasting the decomposition of fat is increased due to the lack of 

 carbohydrate material and acidosis develops. The same holds true 

 for a carbohydrate-free diet. Apparently also fat is much less readily 

 oxidized in the presence of a carbohydrate deficiency. 



2. Messinger-Huppert Method. Principle. This method differs from the 

 preceding in that distillation of the acetone is substituted for aspiration. It is an 

 accurate method of determining acetone and diacetic acid together. 



Procedure. Place 100 c.c. of urine in a distillation flask and add 2 c.c. of 50 

 per cent acetic acid. Connect the flask with a condenser, properly arrange a re- 

 ceiver, attach a terminal series of bulbs containing water, and distil over about 

 nine-tenths of the urine mixture. Remove the receiver, attach another, and sub- 

 ject the residual portion of the mixture to a second distillation. Test this fluid for 

 acetone and if the presence of acetone is indicated add about 100 c.c. of water to 

 the residue and again distil. Treat the united acetone distillates with i c.c. of 

 dilute (12 per cent) sulphuric acid and redistil, collecting this second distillate in a 

 glass-stoppered flask. During distillation, however, the glass stopper is replaced 

 by a cork with a double perforation, the glass tube from one perforation passing 

 to the condenser, while the bulbs containing water, before mentioned, are attached 

 by means of the tube in the other perforation. Allow the distillation process to pro- 

 ceed until practically all of the fluid has passed over, then remove the receiving 

 flask and insert the glass stopper. Now treat the distillate carefully with 10 c.c. 



