88 



The Metabolism of Lactating Women. 



By Edward Mellanby, M.A., M.B. (Cantab.), Beit Memorial Besearch 



Fellow. 



(Communicated by Dr. F. G. Hopkins, F.R.S. Received October 3, 1912, — 

 Bead January 23, 1913.) 



CONTENTS. 



PAGE 



1. Previous work 88 



2. The relation of creatin excretion to the involution of the uterus 89 



3. Its relation to mammary gland activity 92 



a. Cases illustrating a quantitative relation between creatin excretion 



and milk secretion 93 



b. A case of mammary gland activitj' and creatin excretion developing 



late after childbirth 97 



c. A case illustrating simultaneously suppressed creatin excretion and 



mammary gland activity 98 



4. The effect of adding casein to the diet of a puerperal woman 100 



5. The independence of the puerperal excretion of creatin and carbohydrate 



metabolism 101 



6. General considerations 106 



7. Summary 108 



1. Previous Work. 



The metabolic changes of pregnancy have been studied by various workers, 

 principally from the point of view of comparing the total output of nitrogenous 

 material with food intake. 



The following results may be taken as proved : — 



(1) There is a marked rise in the output of nitrogen following childbirth. 

 Grammatikati(l), Zacharjewsky (2), and Slemons(3), among other workers, 

 have definitely proved this. 



(2) This increased nitrogen output more than counterbalances the 

 nitrogenous intake, so that women, at this time, lose nitrogen. This is in 

 marked contrast to the storage of nitrogen taking place before delivery. 



The explanations offered by the various workers on these points vary 

 considerably. Heinrichsen (4), Zacharjewsky (2), and Longridge (13) ascribe 

 the increased nitrogen excretion to regressive changes in the puerperal woman, 

 particularly changes affecting the uterus. Grammatikati(l) thought it was to 

 be explained by mammary gland changes, more especially by the formation of 

 milk fat from protein and the excretion of the nitrogenous residue. 



One other point of interest observed by Slemons(3) is that the total 

 nitrogen of the urine is less on the day of delivery than any other day and 

 that the drop is greater the more prolonged the labour. 



