ON AGE AND METABOLISM AND ON THE SIGNIFICANCE OF THE EXCRETION OF CREATINE

1. From the analyses of the urines of children it is seen that the protein metabolism of the child exhibits differences from that of the male adult. 2. Creatine occurs in the urine of children. The creatinuria in boys ceases about the age of 5 or 6; in girls it persists longer than in boys: in some cases it may even perhaps go over to the intermittent creatinuria which characterises the female sexual cycle. 3. The creatinine‐nitrogen coefficient is much lower in children than in adult men. The creatinine‐nitrogen coefficient increases more rapidly during the first few years of life than in later childhood. 4. Even small quantities of creatine (about 0·3 gm.) are partly excreted by children. In other words, the power to assimilate creatine is very much weaker in children than in adult men. 5. As the result of these observations and of previous investigations on the metabolism of normal women, the conclusion is drawn that creatine is constantly being formed as a product of normal metabolism, and that it is constantly being further metabolised. The excretion or non‐excretion of creatine in the urine depends upon the balance between these two processes of the formation and the destruction of creatine. The various far‐reaching conclusions which have been drawn by different authors on the significance of the excretion of creatine in pathological conditions are briefly discussed. I wish to thank Dr Cramer for his valuable criticisms in connection with this work. My thanks are also due to Drs John Thompson, J. S. Fowler, and Harry Rainy for their kindness in allowing me to make use of the clinical material under their care. The expenses of this research were defrayed by a grant from the Earl of Moray Fund for the Prosecution of Research in the University of Edinburgh.