Concentrations of salivary testosterone and plasma total, non-sex-hormone-binding globulin-bound, and free testosterone in normal and hirsute women during administration of dexamethasone/synthetic corticotropin

Preliminary data indicate that the concentration of circulating cortisol may affect the binding of testosterone to plasma proteins. This interdependency was evaluated by the assessment of plasma cortisol, salivary (ST) and plasma total testosterone (TT), testosterone not bound to sex-hormone-binding globulin (n-SHBGT), and free testosterone (FT) in normal and in hyperandrogenemic women during combined dexamethasone/synthetic corticotropin administration. The concentrations of TT, FT, and ST significantly increased (P less than 0.001) during this dynamic test both in the controls and in hirsute women. Remarkably, however, n-SHBGT remained virtually unchanged in normal women in the follicular phase, decreasing in the luteal phase, and decreasing even more markedly in the hirsute women. Both the normal and the hirsute women showed a statistically significant negative correlation between the percentage of n-SHBGT and plasma total cortisol (P less than 0.001). The apparent decrease of n-SHBGT was the result of displacement of T from corticosteroid-binding globulin (CBG) by the increase in cortisol after the infusion of synthetic corticotropin: the CBG-bound T was measured as n-SHBGT because CBG was not precipitated with 50% saturated ammonium sulfate. Our results indicate that ST or FT better represents the clinical status of androgenicity than does n-SHBGT, as assessed by ammonium sulfate precipitation, because n-SHBGT also depends on the concentration of cortisol.