Plasma free and protein-bound testosterone in hirsutism.

Blood samples were obtained from 145 preovulatory and postovulatory hirsute women and the plasma was analyzed for total testosterone (T), T index, and free T concentration as well as the fraction of free T percentage and that bound by testosterone-estradiol binding globulin. Fifty-six patients were subjected to a 2-week dexamethasone (DXM) suppression test to delineate the source of androgen excess. Presuppression and postsuppression samples were also analyzed for plasma T concentrations and its free and bound fractions. The total T, T index, and free T were elevated in 58, 66, and 55% of hirsute women, respectively. The percentage of bound T fraction was decreased in only 39% of hirsute women, whereas the percentage of free T fraction was increased in 30% and decreased in 11% of hirsute women. The postovulatory hirsute women had a normal percentage of free and bound T fractions, although their total plasma concentrations were elevated. They also had a lower frequency of abnormal levels in all T measurements than preovulatory hirsute women. The DXM seems to deplete the plasma binding globulin; thus the bound T fractions in the post-DXM samples were lower than the pre-DXM values. The total T may be a better measure than the free T values in evaluation of the DXM suppression test for hirsute women.