Development and Validation of a Fecal Testosterone Biomarker: DISCUSSION(3)


The first phase (a) corresponded to the rapidly available portion of the [14C]testosterone that went directly to highly perfused tissues such as liver and kidney. The second phase (p) corresponded to a slower component in which the testosterone is sequestered in slowly perfused tissues such as adipose tissues. Intraperitoneal dosing may favor the excretion of testosterone in one phase over another. Fecal excretion of testosterone for Mus followed the same pharmacokinetic trends as that of the Peromyscus, but fewer time points were used in determination of the kinetic parameters. Knowledge of the lag times for excretion is important in determination of the relationship between physiological events and the detection of changes in the feces. buy flovent inhaler

Radioactivity in feces was associated with both the polar and the nonpolar phases of extraction. These results are consistent with studies of other steroids, which have been shown to exist in the conjugated and the unconjugated form in the feces. Extraction using solubilization of the sample with 10% methanol effectively recovered 87% of the radiolabel, but HPLC separation showed large polar peaks with negligible nonpolar peaks. Reextraction with ethyl ether and HPLC separation resulted in an increase in the size of the nonpolar peaks. When one is measuring total radiolabel excretion, the feces should be extracted using both solubilization and solvent extraction. For measurement of unconjugated testosterone with the ELISA, only an ether extraction is necessary.

This entry was posted in Testosterone and tagged Biomarker, Mus musculus, Peromyscus maniculatus, Testosterone.