Assessment of androgen function in both males and females has previously depended upon indirect parameters such as measurement of urinary excretion of 17-ketosteroids. This procedure measures the excretory products of several weakly androgenic substances secreted by adrenal glands and gonads. However, testosterone, which appears to be the major effective androgen in the female as well as in the male, is not excreted as a 17-ketosteroid.
The accurate diagnosis of male hypogonadism is now made possible by measurement of serum testosterone. If testosterone measurements are low, a simultaneous determination of serum LH will differentiate primary testicular disease from hypogonadism secondary to pituitary disease. Because of the feedback relationship between the testis and pituitary, LH levels should be high in the presence of low testosterone due to primary gonadal disease.
Studies of testosterone values in hirsute women have shown higher mean values of testosterone as compared to normal women, although overlap occurs with the normal range (1). Patients with elevated levels treated pharmacologically with such agents as dexamethasone have frequently shown reduction in testosterone levels (2,3). Very high values seen in women with hirsutism and menstrual irregularities suggest the possibility of adrenal or ovarian tumors. Estrogen treatment or pregnancy will also cause increase in total testosterone levels due to increases in sex hormone binding globulin (SHBG). In these situations, the physiologically active or free component of testosterone remains normal.
Only1-2% of the testosterone circulating in plasma is free; the rest is bound to serum proteins and especially to SHBG and albumin. The free fraction reflects the metabolically available portion of testosterone and it is therefore clinically important (4,5).
In saliva, testosterone occurs in the free form and enters the saliva via intracellular mechanisms (6) and reflects the level of free testosterone in plasma.
The Pantex Salivary Direct Testosterone EIA kit, Cat # 635 is based on the competition principle and microplate separation. Testosterone calibrators of known concentration, unknown amounts of testosterone in saliva samples and a fixed amount of testosterone (analog) conjugated to horse radish peroxidase (Testosterone-HRP) compete for binding sites with a rabbit monoclonal antiserum bound to GARGG (goat anti-rabbit gamma globulin) coated wells of a microplate. After incubation, unbound components are washed away, enzyme substrate solution is added and a blue color formed. This reaction is stopped with an acid solution to produce a yellow color. The optical density is then read at 450 nm. The amount of Testosterone-HRP detected is inversely proportional to the amount of testosterone in a sample.