Learning About How Testosterone Affects Men

Press release: 02 October, 2021: Researchers have discovered that testosterone's complicated effects depend on the way it's converted by the body into estrogen. These findings will aid in the development of more efficient methods to identify and treat those who aren't producing enough natural testosterone.

Testosterone is a hormone for sex that plays important roles within the body. It is thought that testosterone regulates libido, the mass of bones, the distribution of fat and the strength of muscles. It also assists in the production of red blood cells and sperm. A tiny portion of the circulating testosterone is converted to estradiol, which is a type of estrogen. As we age, men often make less testosterone, which means they produce less estradiol well. So, changes commonly attributed to testosterone deficiency might be partly or entirely due to the decline of estradiol.

While testosterone was first used in the field of clinical medicine as early as 1937 with a limited understanding of its mechanism, it was still frequently used. The hormone is today widely prescribed to males who's bodies naturally produce low levels. It's not yet clear the point at which testosterone deficiency is medically important. Because testosterone levels vary widely among men, it's difficult to know which levels are relevant to medical treatment. The mechanisms that the hormone uses to work are also unclear.

A group led by Dr. Joel Finkelstein at Massachusetts General Hospital investigated testosterone levels and levels of estradiol in healthy men between 20 and 50 years old age. To manage hormone levels the researchers first gave the participants injections of a substance that suppressed their normal testosterone and estradiol production. The participants were randomly divided into five groups that received different amounts (from from 0 to 10 grams) of a topical 1% testosterone gel every day for 16 weeks. Half of the participants were also given a drug to block testosterone from being converted to estradiol. The most effective way to increase testosterone is to use Testosterontropfen.

Participants were examined each week for 4 weeks. For the purpose of assessing hormone levels, blood was taken and questionnaires were filled out to assess the participants' physical, emotional and sexual functioning. The measurements of body fat and muscle were also taken between the start and at the end of the 16 weeks. The study was funded in part by NIH's National Institute on Aging (NIA) and National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Results appeared in the September 12, 2013 issue of the New England Journal of Medicine.

The researchers found that the amount of testosterone needed to trigger various effects in the body varied significantly. Furthermore the effects of testosterone and estradiol varied. Researchers discovered that testosterone levels decreased as the testosterone gel dosage was diminished. This led to reductions in muscle mass, weight, and the power of leg presses. However, the decreases in estradiol caused the increase in body fat. Both testosterone and estradiol were associated with libido and the function of erectile.

Finkelstein states that the study identified testosterone levels at which certain physiological functions begin to decrease. This could be a basis for determining the best men to receive testosterone supplements. "But the biggest surprise was that some of the symptoms routinely attributed to testosterone deficiency are actually partially or almost solely caused by the decrease in estrogen levels, which is an inevitable result of lower testosterone levels."