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QUARTERLY JOURNAL OF MEDICINE 



As a urea concentration test had been carried out nine hours previously, the 

 small increases in the blood urea at 7 p.m. on 3.11.24 might have been due to the 

 excess of urea in the blood not having been completely excreted. Accordingly 

 the blood urea was estimated on days on which no- urea concentration test was 

 carried out and on which the vasodilator drug was administered : 



Blood Urea in Tng. 



It would appear therefore possible to exclude as a cause of the increased 

 percentage of urea in the urine the possibility of a retention of blood urea in the 

 early stages of the administration of the vasodilator drug in healthy subjects. 

 The excess of urea in the blood resulting from a dose of 15 grm. urea does 

 not appear to be excreted completely in nine hours in the case of the healthy 

 subjects considered above, although the residual amount is small. 



The above observations with regard to the blood urea content in the early 

 stages of the vasodilator administration were repeated on six subjects with raised 

 blood-pressure. There was no evidence of an early retention of blood urea, which 

 might conceivably have been a factor in the increased percentage of urea in the urine. 



The total amount of urea excreted daily was examined in two healthy 

 cases and in two high blood-pressure cases before and during the administration 

 of vasodilator drug, no urea being given. 



Table V. 



Noi-mal Day. Day with Vasodilator Drug. 



