STARVATION 603 



comparing the creatine and creatinine output with, that of nitrogen to 

 determine whether all of the nitrogen liberated by the breakdown of 

 muscle has been excreted, or whether some has been retained either for 

 resynthesis in the muscle itself or for use elsewhere. As a matter of fact 

 the muscle breakdown as calculated from the creatine-creatinine output 

 is greater than that calculated from the nitrogen, indicating that synthesis 

 of the noncreatine remainder must be occurring. 



That transference of nitrogenous substances from place to place in the 

 body in starvation is proved (1) by the constant presence of amino ni- 

 trogen in the blood and tissues (Van Slyke) ; and (2) by the effect of 

 copious water drinking. The latter causes a decided increase in the out- 

 put of nitrogen, because of the excretion of some of the nitrogenous 

 substances. It is probable, however, that in such cases there is also a 

 subsequent increase in endogenous protein metabolism, since the w r ashed- 

 out free nitrogen would have to be replaced. 



Excretion of Purines. Although at first they fall somewhat, the total 

 amount increases as the fast progresses. Perhaps the first decline is 

 due to general using up of hypoxanthine of muscle and the later rise 

 to the breakdown of nuclei (page 671). 



Excretion of Sulphur. It is important to compare the excretion of 

 sulphur and nitrogen. In the early days of starvation a ratio of 17 N : 1 S 

 has been found, but later one of 14.5:1, which is practically the same 

 as that in muscle (i.e., 14; 1), indicating that late in fasting the main 

 source of protein supply is muscle. 



Several of the changes observed during starvation can be attributed 

 to the condition of acidosis which supervenes. The acids are derived 

 from incomplete combustion of fat (see page 715), and are represented 

 by /?-oxybutyric, the amount being sometimes considerable (10-15 grams 

 a day), especially in obese individuals. The large ammonia excretion 

 (sometimes 2 grams a day) is evidently for the purpose of neutralizing 

 the excess of acid. Another consequence of the acidosis is the decline 

 in the alveolar tension of CO., (page 379), and it is possible that some of 

 the circulatory changes shown in the chart may also be dependent on 

 it. For reducing obesity the method of repeated fasting is quite safe 

 provided the acidosis is carefully watched and the diet which is given 

 contains accessory food factors (page 618). 



Many secondary changes also occur in the starving organism. Thus, 

 the mobilization of fat is often responsible for a pronounced increase in 

 the fat content of the blood (see page 698). 



The amino nitrogen of the blood is riot perceptibly reduced by starva- 

 tion (page 613) but early in the condition the blood sugar becomes much 

 lower than normal, after which it remains steady. This is significant 



