222 Freeman, Pincus, Elmadjian and Romanoff 



older groups. An analysis of the change in values from the 

 basal level to the two and four hour readings shows a statisti- 

 cally significant difference between tlie young and old schizo- 

 phrenic subjects but not between the yoinig and old normal 

 men. 



The greater excretion of creatinine following ACTH in the 

 aged may be influenced by the differences in the initial levels 

 between young and old. There is a negative relationship 

 between the basal values and the change in four hours so that 

 the lower initial values show greater changes than the higher 

 basal values. Correlation coefficients for the four groups are 

 as follows: young normal, —0-23; young schizophrenic, —0-66; 

 old normal, —0-67; old schizophrenic, —0-66. Only in the 

 young normal group is this relationship not significant. 



The data on creatinine excretion following the ingestion 

 of glucose show the same trend as with ACTH (Table I). 

 Again the young subjects, both normal and schizophrenic, 

 exhibit no significant change in values over the experimental 

 period while the old subjects show a distinct increase. The 

 increase in excretion at the three-hour point is significantly 

 higher in both older groups than for the corresponding- 

 younger subjects. Further, the relationships between the 

 basal values and the changes at three hours are of the same 

 order of magnitude as in the case of ACTH. 



It may be that the initially higher values of the young 

 subjects represent not merely the degradation products of 

 greater muscular activity but also a more efficient renal 

 mechanism which, under stress, is able to maintain a given 

 level of excretion. The impairment of renal function in the 

 old may be manifested in an inability to resorb the increased 

 amount of creatinine presented by the stimulating agent. 



Not merely does creatinine vary but the other urinary 

 metabolites vary with it. In Table II are shown the relation- 

 ships between basal values for creatinine and the other 

 functions studied, in the old normal and schizophrenic subjects. 

 The correlations are of a good high order of magnitude, the 

 highest relationships being obtained with phosphates, sodium 



