The percentage of free 3 H-T is multiplied by the total testosterone to calculate the FT of the sample. Direct assays, however, may overestimate actual testosterone levels and show limited accuracy at lower testosterone levels18. The Hypogonadism In Men (HIM) study found the odds ratio for having low total testosterone to be 1.84 for hypertension, 2.09 for diabetes, and 2.38 for obesity11. have been undertaken on the relationship between more general aggressive behavior, and feelings, and testosterone. Nearly all studies of juvenile delinquency and testosterone are not significant. On the other hand, elevated testosterone in men may increase their generosity, primarily to attract a potential mate. Testosterone levels play a major role in risk-taking during financial decisions. Men who produce less testosterone are more likely to be in a relationship or married, and men who produce more testosterone are more likely to divorce. However, the testosterone changes observed do not seem to be maintained as relationships develop over time.} Conflicting results have been obtained concerning the importance of testosterone in maintaining cardiovascular health. In people who have undergone testosterone deprivation therapy, testosterone increases beyond the castrate level have been shown to increase the rate of spread of an existing prostate cancer. The levels remain in a pubertal range for a few months, but usually reach the barely detectable levels of childhood by 4–7 months of age. Examples include genital virilisation such as midline fusion, phallic urethra, scrotal thinning and rugation, and phallic enlargement; although the role of testosterone is far smaller than that of dihydrotestosterone. The relative potency of these effects can depend on various factors and is a topic of ongoing research. Testosterone is a steroid hormone from the androstane class containing a ketone and a hydroxyl group at positions three and seventeen respectively. This method is recommended for testing women, children, and hypogonadal men. The plasma protein binding of testosterone is 98.0 to 98.5%, with 1.5 to 2.0% free or unbound. Like other steroid hormones, testosterone is derived from cholesterol (Figure 1). The part of the total hormone concentration that is not bound to its respective specific carrier protein is the free part. Lipophilic hormones (soluble in lipids but not in water), such as steroid hormones, including testosterone, are transported in water-based blood plasma through specific and non-specific proteins. Therefore, these mammals may provide a model for studying clinical populations among humans with sexual arousal deficits such as hypoactive sexual desire disorder. Studies conducted in rats have indicated that their degree of sexual arousal is sensitive to reductions in testosterone. Testosterone levels follow a circadian rhythm that peaks early each day, regardless of sexual activity. Common side effects from testosterone medication include acne, swelling, and breast enlargement in males. Two of the immediate metabolites of testosterone, 5α-DHT and estradiol, are biologically important and can be formed both in the liver and in extrahepatic tissues. Certain cytochrome P450 enzymes such as CYP2C9 and CYP2C19 can also oxidize testosterone at the C17 position to form androstenedione. In addition to 6β- and 16β-hydroxytestosterone, 1β-, 2α/β-, 11β-, and 15β-hydroxytestosterone are also formed as minor metabolites. Various factors can alter physiological levels of SHBG and, with them, levels of bioavailable testosterone (see table 1). Circadian rhythms influence testosterone with levels peaking in the morning4. Bioavailable testosterone (BT) refers to both free testosterone and that which is bound to albumin. Testosterone that is complexed to albumin is weakly bound and has androgenic potential.
