What is Testosterone?
Testosterone is one of the families of hormones known as steroids. You might be surprised to know that steroids are derived from nature. The steroid is composed of a “ring-structure” (see picture [INSERT PICTURE filed steroid_molecule.jpg but cannot figure out how to wrap text around it]) which is chemically converted from cholesterol. (You’ve heard that cholesterol is bad for you, and the lower its level in your blood the better. However, cholesterol is actually one of your body’s most important molecules. Being a forerunner to these important testosterone steroid hormones is one of the reasons for that.) In fact, it is just minor adjustments (like adding or deleting side chains or electrons) to that ring structure that distinguishes molecules with profoundly different effects, such as estrogen, progesterone, DHEA, cortisone, and androstenedione, to name a few. They are also small molecules. Size becomes important when we look at the methods of administration that are available.
Of the testosterone circulating in your bloodstream, 95% is produced in your testicles, influenced by luteinizing hormone (LH), which is released from your pituitary gland. Over 24 hours, LH is released in spurts that stimulate the testicles to release testosterone. Those signals are particularly strong in the early morning thus, the higher morning testosterone levels encouraging increased libido and spontaneous morning erections. By late evening, testosterone levels can fall by 50%. The lower levels indicate to the pituitary gland that it should accelerate production of LH and begin the cycle anew.
Total testosterone vs. free testosterone: the distinction is important
In any discussion of testosterone levels, it is important to differentiate between the total and free fractions of the hormone that are found in the blood. Between 97% and 99% of testosterone stowed in your bloodstream is attached to a protein cleverly called the ‘sex hormone binding globulin’ (SHBG). The SHBG keeps your testosterone from being removed into the urine too quickly from your kidneys. Slowing elimination maintains a steady supply of testosterone for your tissues. Free testosterone is biologically more important because this portion of testosterone is the only part that can disperse into the tissues that use testosterone and change your physiological function.
Can you raise testosterone using DHEA or androstenedione?
Along with the production in your testicles that accounts for the overwhelming majority of circulating testosterone, a lesser amount can be created by converting precursor steroid hormones like androstenedione and androstenediol. You probably learned about these hormones when Mark McGwire (St. Louis Cardinals home run king) admitted using them. They are sold over the counter with names like Andro-this or that. Sadly for McGwire, recent studies demonstrate that larger portions of androstenedione are converted into estrogens instead of testosterone. Because of that there is no sustained muscle-enhancing effect. Instead, estrogen stays elevated for a longer period of time and may cause gynecomastia, which is enlargement of male breast tissue. The result of use becomes feminization of the user rather than increasing muscle and masculine features. McGwire has discontinued using them now, so it is assured that his current muscularity and awesome hitting power are not the results of his prior androstenedione use.Testosterone is NOT…
We want to clarify some public misconceptions about what testosterone is and is not. Yes, testosterone is one member of the group of compounds called ‘anabolic steroids’ or muscle- and bone-building molecules. However, it is different from what people think of as anabolic steroids—those often abused by body builders and professional athletes. The kinds that are abused (decadurabolin, oxandrolone, and methyltestosterone) have different molecular structure than testosterone. Plus, they are not normally found in a human body. Because of their changed molecular structure, these potent anabolic hormones have been shown to have adverse effects on organ systems, particularly the brain and liver. So, even though they have similar muscle-building effects, the side effects are neither similar nor desirable. Unscrupulous doctors and others sold these drugs on the “black market.” They were given in high doses to young men and professional athletes. To counter the damage being done, those hormones—including testosterone—are now regulated as schedule III substances (such as morphine and narcotic drugs). Testosterone’s image has been tarnished for many doctors and the general public. This is unfortunate because many people would benefit from responsible well-monitored TRT.
NEXT PAGE: Effects of low T
