CREATINE AND CREATININE 177 



4.— CREATINE AND CREATININE 



These two substances contain the guanidine group — 



I 

 HN=C 



I 



Creatine is methyl guanidine acetic acid — 



NH CH3 



II I 



C N-CH2-COOH 



I 

 NH2 



It occurs in all tissues, but principally in skeletal muscle 

 (0-4 per cent.). In normal adult urine it occurs only 

 after a meat diet. It appears during starvation and in 

 fevers. It is constantl}^ present in the urine of children, 

 and in the urine of women during pregnancy and men- 

 struation. 



Creatinine — 



NH CH3 



II I 



C N— CH2 



NH CO 



is a dehydration product of creatine which can be obtained 

 by boihng creatine with acids. It occurs in normal urine, 

 1-2 grms. being excreted daily. 



Effect of Administration 



When creatine is given by the mouth some undergoes 

 bacterial decomposition in the intestine, some appears in 

 the urine partly as creatine, partly as creatinine, and some 

 disappears. 

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