542 



ADVEXTURES IN RADIOISOTOPE RESEARCH 



EXCRETION EXPERIMENTS 



The most suitable method of analysis of urine was found to be the following: 

 Evaporate to dryness an aliquote, preUminarily treated with fuming nitric acid 

 and determine its activity. Another smaller known fraction is digested in a Kjel- 

 dahl flask and its P content determined by the method of Fiske and Subbarow. 

 The method tried first, based on the precipitation of ammonium magnesium 

 phosphate from the urine, was found to be unsatisfactory, as activity measure- 

 ments have shown that a part of the inorganic P present in the urine, remains 

 in solution after precipitation with magnesia or the magnesium citrate reagents. 

 In view of the low activity of many of the faeces samples, we had to work up seve- 

 ral gm of dry faeces. It was too troublesome to dissolve such a comparatively 

 large amount; we have therefore chosen the following procedure: The sample was 

 first treated with nitric acid and then dried on a sand bath below 300°, to avoid 

 loss of phosphorus. The activity of the substance was then determined. Another 

 known part of the faeces sample, in most cases weighing only 30 mgm, was dige- 

 sted in a Kjeldahl flask and its P content determined by the colorimetric method. 



Table 1 



Time after administration 

 of labelled P 



Volume of urine 

 in cc. 



Specific activity of urine P 

 (% of the labelled P admi- 

 nistered found in 1 mgm P) 



3 

 5 



7 

 10 

 11 

 22 

 27 

 34 

 44 



3 



6 

 8 

 13 

 16 

 26 

 32 

 43 



hours 



days 



Excretion of labelled phosphorus through the kidneys 



In the experiment described first, the urine of a 40 years old female patient 

 suffering from diabetes was investigated. The labelled sodium phosphate of negli- 

 gible weight was given with a glass of millc. We intended originally to investigate 

 the excretion of the above mentioned patient after treatment with insulin as well. 

 However, because the patient was soon discharged from the hospital, this investig- 

 ation could not be carried out. 



