The determination of thiamine in the blood of human subjects

Graduation date: 1950The blood thiamine concentration of 11 subjects was determined\ud by means of the Friedemann and Kmieciak (1943) method every 5 days\ud during a 30-day experimental period. Study I was conducted on 5\ud students in 1947 and Study II was conducted on 6 students in 1948.\ud The subjects in both studies were on diets in which their intake of\ud ascorbic acid only was controlled. A record was kept of each subjects\ud food intake. The daily values for total Calories, non-fat Calories\ud and thiamine in the diet were obtained from food tables. Non-fat\ud Calories, the ratio of non-tat Calories to total Calories, thiamine\ud to 1000 Calories and thiamine to non-fat Calories were calculated.\ud The blood thiamine values for the subjects in Study I (all girls)\ud ranged from 4.91 to 10.85 mcg per cent. There was a general decrease\ud throughout the study in the mean intake of thiamine expressed in terms\ud of mcg per 1000 Calories and mcg per 1000 non-fat Calories. The greater\ud the decrease in thiamine intake in terms of mcg per 1000 non-fat Calories\ud the greater was the loss of blood thiamine. The values for thiamine in\ud the blood of the boys in Study II ranged from 8.00 to 15.32 mcg per cent\ud and for the one girl in Study II from 8.35 to 13.93 mcg per cent. The\ud blood thiamine values for the subjects in Study II did not indicate the\ud same relationship to thiamine intake as did those in Study I. There was\ud an increase in the concentration of the thiamine in the blood even though\ud there was a decrease in the mean thiamine intake from the beginning to the\ud end of the experiment. It would appear, therefore, that the boys obtained\ud sufficient thiamine throughout the 30-day period.\ud No data have been obtained which indicate whether or not there are\ud variations from day to day in the concentration of thiamine in the blood\ud when subjects are maintained on a constant intake of thiamine. A\ud metabolism study using 5 adult women as subjects was planned in order to\ud determine the daily values for thiamine in the blood when subjects were\ud maintained on a controlled diet for a period of 52 days. An unpublished\ud micro-method for the determination of thiamine in the blood developed by\ud Dr. H. Burch (1948) was to be used.\ud The experimental diet consisted of a basal diet providing approximately\ud 1000 Calories and 300 mcg of thiamine with additions to the basal\ud diet planned in units providing approximately 500 Calories and 150 mcg of\ud thiamine. The values for protein, fat, carbohydrate and total Calories were obtained, from food tables. Non-fat Calories were calculated and\ud the thiamine content of the food was determined by analysis. All 5\ud subjects ate the same food each day.\ud In spite of the fact that considerable preliminary work was performed\ud before the study started the blood thiamine values obtained in\ud the nutrition laboratory were always significantly lower than results\ud obtained by other workers. It was decided to freeze the blood samples\ud after the protein had been removed and work on certain aspects of the\ud method before any analyses of the blood thiamine were made.\ud Further study of the Burch method included variation in the amounts\ud of potassium acetate used, use of different trichloroacetic acid reagents,\ud tests for enzyme activity, variations in the incubation procedure,\ud variations in the procedure for the oxidation to thiochrome and in the\ud extraction of thiochrome, reading samples sooner after transfer to\ud optically matched tubes, variations in the irradiation procedure, use of\ud all new reagents, use of another micro-photofluorometer, development of\ud standard curves and the determination of the response of two subjects to\ud an oral test dose of thiamine hydrochloride. None of these variations\ud resulted in a solution of the problem.\ud Suggestions for future work with the Burch method are discussed