Low Testosterone means diminished functional activity of the gonads—the testes in males or the ovaries in females—that may result in diminished sex hormone biosynthesis. In layman's terms, it is sometimes called interrupted stage 1 puberty. Low androgen (e.g., testosterone) levels are referred to as hypoandrogenism and low estrogen (e.g., estradiol) as hypoestrogenism, and may occur as symptoms of hypogonadism in both sexes, but are generally only diagnosed in males and females respectively.
After age 30, most men begin to experience a gradual decline in testosterone. A decrease in sex drive sometimes accompanies the drop in testosterone, leading many men to mistakenly believe that their loss of interest in sex is simply due to getting older