Excretion of Thiamin and its Degradation Products in Man. ∗

Abstract

The development of a simple procedure 1 to determine both thiamin and the pyrimidines in human urine permits the investigation of the possible relationship between the two.

Schultz, Atkins and Frey showed that the rate of glucose fermentation by a yeast is directly proportional to the concentration of thiamin present. In addition to thiamin, the pyrimidines give mol for mol stimulation effect on the rate of fermentation. Such pyrimidines are found normally in human urines. Since the pyrimidine nucleus constitutes an integral part of the thiamin molecule, it is of interest to determine the relationship between thiamin and urinary pyrimidine.

The total fermentation is a measure of thiamin and pyrimidine in the urine. The fermentation after oxidation of the free thiamin is a measure of the pyrimidines; the difference represents the free thiamin. This technic combines the gas method with the initial steps of the thiochrome procedure.

The urinary excretion of the thiamin and pyrimidine of a group of patients was studied under various conditions. Three patients were given a diet completely deficient in B₁ for 10 days. Two of these were normal and one had ileo-jejunitis. Fig. 1 and 2 and Table I illustrate that complete deprivation of dietary thiamin for a period of 10 days changed the thiamin-pyrimidine ratio from approximately 9:1 to 1:9. During this 10-day deprivation period, the absolute amount of pyrimidine excreted remained at approximately the same level, while the free thiamin disappeared almost completely. It becomes apparent, then, that the determination of free thiamin in the urine is an index of the dietary intake immediately preceding the measurement, since the urinary excretion of thiamin decreases so rapidly on deprivation. Therefore, low values for free thiamin need not necessarily indicate a state of chronic insufficiency with respect to this vitamin since the same values are obtained with temporary, acute deprivation.