EXCRETIONS 491 



fully confirmed by many subsequent investigators and Shaffer (a) has fur- 

 ther observed the same uniformity in its hourly excretion. (According to 

 Neuwirth the hourly creatinin excretion is generally slightly decreased 

 during one hour in the later afternoon or early evening). Even a con- 

 siderable diuresis has little effect on this hourly output, while a great 

 increase or decrease in the amount of total nitrogen excreted per hour is 

 likewise without effect. Furthermore, neither increased nor decreased 

 muscular activity, uncomplicated by other factors, has any effect upon 

 the creatinin elimination. Such results are a definite indication that 

 the regularity of the creatinin excretion can be explained only on the 

 basis of a similar regular formation. 



While the creatinin excretion is practically constant for each healthy 

 individual, different persons excrete different amounts, and Folin early 

 pointed out that the chief factor determining this appeared to be the 

 weight of the person. He further noted that the fatter the subject, the 

 less creatinin is excreted per kilo of body weight and concluded from this 

 that the amount of creatinin excreted depends primarily upon the mass 

 df active protoplasmic tissue, or as Shaffer has expressed it, "Creatinin. 

 is derived from some special process in normal metabolism taking place 

 largely, if not wholly, in the muscles, and upon the intensity of this 

 process appears to depend the muscular efficiency of the individual." It 

 has been found convenient to express the daily creatinin elimination in 

 milligrams of creatinin nitrogen per kilo of body weight and this has 

 been called the creatinin coefficient. For a strictly normal individual 

 Shaffer has shown that this coefficient is between 7 and 11. Women elimi- 

 nate less creatinin than men, and thus have slightly lower creatinin. 

 coefficients. The creatinin excretion of children is much lower than that 

 of adults. 



That the creatinin elimination is affected by different pathological 

 conditions has been shown by numerous observations. A low creatinin 

 elimination has been found associated with a large number of abnormal 

 conditions, especially those accompanied by muscular weakness. Benedict 

 and Myers observed creatinin coefficients as low as 2 in two very old 

 decrepit women, while Levene and Kristeller found coefficients of 1.5 in 

 several cases of muscular dystrophy in young male adults. A marked 

 decrease in the excretion of creatinin has been observed to be associated 

 with such conditions as exophthalmic goiter, the leucemias, diseases of 

 the liver, especially carcinoma, muscular dystrophy, anterior poliomyelitis, 

 certain cases of nephritis, etc, An interesting fact to note in this con- 

 nection is that most of these subjects eliminate considerable amounts of 

 creatin. 



Only in the terminal stages of chronic nephritis is a decreased elimi- 

 nation of creatinin due to retention. Creatinin appears to be the most 



