1912.] 



The Metabolism of Lactating Women. 



107 



that pyrexia is avoided at these times, and the cause of the fever is 

 undoubtedly some substance formed in the mammary gland and absorbed 

 in excess into the general circulation. It may be that the substance 

 formed in the mammary gland and responsible for the pyrexia of the 

 puerperium may also account for the creatin excretion at this period and 

 the great metabolic changes which result in the transference of nutrient 

 material to the breasts. Another hypothesis which links up the same facts 

 is that toxic substances may be formed as waste products in the mammary 

 gland and ovum at early stages of development and that these substances 

 cause the excretion of creatin. Certainly, in several cases where there was 

 slight pyrexia after parturition, associated with mammary gland congestion, 



would fall into line with the fact that the best milking mothers excreted the 

 most creatin. 



The fact that creatin is also excreted during pregnancy indicates that there 

 is nothing specific about the probable relation of creatin excretion and 

 mammary gland activity. In the adult person it seems to be a general 

 reaction indicating some abnormal condition affecting the transport of 

 nutrient material, such, for instance, as that which must accompany the 

 growth of a foetus* or the development of milk secretion. Such a general- 

 isation would include the metabolic condition of carbohydrate deficiency, 

 where, again, creatinuria is present. Also, the results of Mendel and 

 Kose (18), who observed the excretion of creatin in all stages of childhood 

 and adolescence, suggest the association of creatin with the transport of 

 material necessary for the growing tissues. 



In most of the other conditions brought to light in which large quantities 

 of creatin are excreted, it has been possible to show that the liver is 

 primarily affected : such conditions for instance as cancer of the liver, 

 deficiency or abnormality of carbohydrate metabolism, toxaemias directly 

 affecting the liver as when a septic focus is in the abdominal cavity, and 

 after operative interference with parts of the body supplied by the portal 

 circulation.! It has not been possible to get any evidence of liver 

 abnormality in the case of lactating women, but, by analogy, it might be 

 expected that here also the liver holds the key to the situation. 



The conditions in which creatin is excreted may be divided into two 

 groups. 



* We are endeavouring to find out whether there is any relation between the creatin 

 excretion of a pregnant woman and the development of the foetus, 

 t These latter two conditions I shall consider elsewhere. 



I found a high 



creatin 



ratio in the urine. Such an explanation, also, 



creatin in 



