Estimation of testosterone binding capacity in the serum with hydrophobie resin.

A method for the estimation of the serum testosterone binding capacity (TeBC) using hydrophobic resin, Amberlite XAD-2, was developed. The serum was incubated with a saturating amount of testosterone-1,2(-3)H at 15 degrees C, unbound testosterone was adsorbed to the resin and the 3H-radoiactivity remaining in the supernatant fluid was counted. Under these conditions, the normal levels and their standard deviations were 15.08+/-3.39 ng/ml (n=7) for male and 35.06+/-3.56 ng/ml (n=6) for female respectively. Precision of the method was 6.29%. TeBC in the third month of pregnancy was approximately 1.5 times more than that of non-pregnant women, and approximately 3 to 5 times in the tenth month.