Testosterone

Testosterone is a 19-carbon steroid hormone produced primarily by the Leydig cells of the testes (in men) and the ovaries (in women). Smaller amounts are produced in the adrenal glands of both sexes. As a "steroid", testosterone belongs to the androgen class of hormones that also includes dihydrotestosterone (DHT), dehydroepiandrosterone (DHEA), androstenedione, and androstenediol.

Six other classes of steroid hormones exist, including estrogens (the bane of male bodybuilders), progestins (some female contraceptives are made of these), mineralocorticoids (which help control water balance), glucocorticoids (mainly anti-inflammatory compounds), vitamin D, and bile acids.In men, approximately seven mg of testosterone is produced each day, and blood levels range between 300 and 1000 ng/dL (10-28 nmol/L). Females, on the other hand, produce about 1/15th of this amount, leading to average blood levels of only 25 to 90 ng/dL (1-2.5 nmol/L). All steroid hormones are derived from the sterane ring structure, composed of three hexane (6 carbon) rings and one pentane (5 carbon) ring.

Types of Testosterone

1. Free Testosterone. This is testosterone in its purest form. It’s the crack of testosterone, if you will. The reason it’s called “free” is because there aren’t any proteins attached to it. Unbound to other molecules, free T can enter cells and activate receptors in order to work its virile magic on your body and mind. Despite free testosterone’s benefits, it makes up only 2 to 3 percent of our total testosterone levels

2. SHBG-bound Testosterone. About 40 to 50 percent of our total testosterone is bound to a protein called sex hormone-binding-globulin (SHBG). SHBG is produced in our livers and plays an important role in regulating the amount of free testosterone in our bodies. The downside to SHBG-bound T is that it’s biologically inactive, meaning our bodies can’t use this type of testosterone to help build muscles or boost our mood

3. Albumin-bound Testosterone. The rest of our testosterone is bound to a protein called albumin. Albumin is a protein produced in the liver, and its job is to stabilize extra-cellular fluid volumes. Like SHBG-bound testosterone, albumin-bound testosterone is biologically inactive. However, unlike SHBG-bound T, the bind between albumin and testosterone is weak and can be easily broken in order to create free testosterone when needed

How Testosterone Is Made

A small percentage of testosterone is made in the adrenal glands on top of our kidneys but  95% of it is made in our testicles.

The whole thing gets kicked off in our brain. When our hypothalamus detects that our body needs more testosterone, it secretes a hormone called gonadotropin-releasing hormone. The gonadotropin-releasing hormone makes its way over to the pituitary gland in the back of our brain.

Benifits

Having an optimal resting level of testosterone is extremely important for male health and body composition. Higher resting levels of T are associated with greater muscle mass, less body fat, better bone strength, and less risk of all-cause mortality as men age.

In addition, it’s been shown that suppressing T in young men who are resistance training leads to less muscle and strength development. The same thing happens to older women with low resting T levels.