Colorimetric Assay of Urinary Androgens

Abstract

In earlier communications by the author 1 , 2 on the colorimetric assay of urinary androgens no data were given on crystalline preparations of the pure hormones normally found in the urine. These data are of value in interpreting colorimetric work and are given here.

Crystalline androsterone (M.P. 180 u.c.) dehydroisoandrosterone (M.P. 135°u.c.) and testosterone (M.P. 152°u.c.) were obtained and weighed quantities made up into 60% alcohol. Color unit and capon assays were carried out on these preparations with the results recorded in Table I.

The biological activity of a color unit from urine extracts was found to be approximately equal to 10 gamma of pure androsterone. This value varies as is evident from the data of Table I of our earlier report. 2 The range in comb growth for a color unit is of necessity wide. This is to be expected since:

1. The chemical reaction used is non-specific.

2. The various androgens found in urine are not always excreted in the same proportions.

3. The variations in the capon assay contribute to this factor and the number of capons used in this work was of necessity small.

4. There are probably other non-active androgen-like color-producing substances (such as undoubtedly result from the hydrolysis treatments) which have evaded attention simply because of their lack of activity.

From the above data we see that one color unit of pure androsterone is represented by 90 gamma of the crystalline material, while one color unit of urine extract is equivalent in biological activity to only 10 gamma of androsterone. This is an expected finding, but one that must be remembered when using the colorimetric method as a guide to quantitative studies.

1. The chemical reaction used is non-specific.