[From British Journal of Experimental Pathology, 

 1923, Vol. IV.] 



67 



A METHOD OF ESTIMATION OF DIASTASE IN 



BLOOD.^ 



a. MATTHEW FYFE, M.B., Ch.B. 



From the Physiological Laboratory, University of Aberdeen. 



Received for publication March 22nd, 1923. 



There is a general acceptance of the view that estimation of blood diastase 

 is of distinct diagnostic value, and it is unfortunate that certain features of 

 recent methods render them not entirely satisfactory. Stocks (1916), and later 

 Harrison and Lawrence (1923), adopting Wohlgemuth's method, incubate a 

 series of dilutions of blood serum, or blood plasma, with starch and obtain their 

 results from the colour reaction which occurs on the addition of iodine. In the 

 first place it is very difficult to obtain in general practice a sufficiency of serum 

 for the purpose of the test (from 1 c.c. to 3 c.c.) without veni-puncture, and, in 

 the second place, sera do occur occasionally of which the tint definitely masks 

 the delicacy of the colour reaction. Myers and Killian (1917), using the Lewis 

 and Benedict method of blood sugar estimation, determine the amount of sugar 

 formed from a known quantity of starch by 2 c.c. blood after incubation for a 

 definite period, calculating their results in terms of the percentage of starch 

 reduced. Here again the question of veni-puncture arises, and in addition that 

 of the inaccuracies which the picric acid methods of sugar estimation present 

 as compared with more recent means of blood-sugar determination. 



In view of these difficulties the problem of the estimation of blood diastase 

 was approached, and, by an adaptation of MacLean's (1919) method of blood- 

 sugar estimation, a means has been evolved which has the advantage of 

 simplicity and accuracy, while it necessitates the minimum of discomfort to the 

 patient. It also permits of an almost concurrent reading of the blood-sugar 

 and the blood-diastase figures, dispensing with the need for two different 

 techniques. For the method proposed 0'2 c.c. blood only is required — an 

 amount which can easily be obtained by pricking the ear or the finger. The 

 final result depends upon a determination of the patient's blood sugar by 

 MacLean's method, and upon a second determination after 0"2 c.c. of the 

 patient's blood has been incubated for half an hour at 37° C. with 1 c.c. of a 

 0"1 per cent, solution of starch. 



The Effect on Blood Sugar of Incuhation at 87° G. 

 In view of the fact that the literature of the subject gives most discordant 

 views on the problem of glycolysis in blood, it was thought best to make an 

 investigation of the question. It was found that under the experimental 

 conditions described below no glycolysis was in evidence. Freshly drawn blood 

 to the amount of 0'2 c.c. was pipetted into a small Erlenmeyer flask containing 

 2'8 c.c. normal saline solution. The suspension was incubated for half an hour 

 in a water-bath at an accurately maintained temperature of 37° C. During 

 this period a direct control estimation of the sugar in another sample of 0*2 c.c. 

 was done. When the incubation time was completed the amount of sugar 

 * Work carried out in the tenure of a Carnegie Research Assistantship. 



