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Before assessing the evidence of testosterone’s action in the aging male it is important to note certain methodological considerations which are common to the interpretation of any clinical trial of testosterone replacement. Many interventional trials of the effects of testosterone on human health and disease have been conducted. There is considerable heterogenicity in terms of study design and these differences have a potential to significantly affect the results seen in various studies. Gonadal status at baseline and the testosterone level produced by testosterone treatment in the study are of particular importance because the effects of altering testosterone from subphysiological to physiological levels may be different from those of altering physiological levels to supraphysiological. Another important factor is the length of treatment. Randomised controlled trials of testosterone have ranged from one to thirty-six months in duration (Isidori et al 2005) although some uncontrolled studies have lasted up to 42 months. Many effects of testosterone are thought to fully develop in the first few months of treatment but effects on bone, for example, have been shown to continue over two years or more (Snyder et al 2000; Wang, Cunningham et al 2004).
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.[151] Approximately 5 to 7% of testosterone is converted by 5α-reductase into 5α-DHT, with circulating levels of 5α-DHT about 10% of those of testosterone, and approximately 0.3% of testosterone is converted into estradiol by aromatase.[2][151][157][158] 5α-Reductase is highly expressed in the male reproductive organs (including the prostate gland, seminal vesicles, and epididymides),[159] skin, hair follicles, and brain[160] and aromatase is highly expressed in adipose tissue, bone, and the brain.[161][162] As much as 90% of testosterone is converted into 5α-DHT in so-called androgenic tissues with high 5α-reductase expression,[152] and due to the several-fold greater potency of 5α-DHT as an AR agonist relative to testosterone,[163] it has been estimated that the effects of testosterone are potentiated 2- to 3-fold in such tissues.[164]
In 1927, the University of Chicago's Professor of Physiologic Chemistry, Fred C. Koch, established easy access to a large source of bovine testicles — the Chicago stockyards — and recruited students willing to endure the tedious work of extracting their isolates. In that year, Koch and his student, Lemuel McGee, derived 20 mg of a substance from a supply of 40 pounds of bovine testicles that, when administered to castrated roosters, pigs and rats, remasculinized them.[179] The group of Ernst Laqueur at the University of Amsterdam purified testosterone from bovine testicles in a similar manner in 1934, but isolation of the hormone from animal tissues in amounts permitting serious study in humans was not feasible until three European pharmaceutical giants—Schering (Berlin, Germany), Organon (Oss, Netherlands) and Ciba (Basel, Switzerland)—began full-scale steroid research and development programs in the 1930s.

As we age, the body undergoes multiple degenerative changes at multiple sites and in multiple systems. The changes of aging are inevitable and inexorable and represent the march toward ultimate death. We are mortal beings whose destiny it is to die. As we come to learn about the processes of life we can better prepare ourselves for the finality of death and on the way perhaps retard the degenerative process, or repair it (for however long we may enjoy this repair), or substitute chemical compounds that our bodies once produced in abundance, an abundance which fades with the advance of age.
Testosterone is a steroid from the androstane class containing a keto and hydroxyl groups at the three and seventeen positions respectively. It is biosynthesized in several steps from cholesterol and is converted in the liver to inactive metabolites.[5] It exerts its action through binding to and activation of the androgen receptor.[5] In humans and most other vertebrates, testosterone is secreted primarily by the testicles of males and, to a lesser extent, the ovaries of females. On average, in adult males, levels of testosterone are about 7 to 8 times as great as in adult females.[6] As the metabolism of testosterone in males is more pronounced, the daily production is about 20 times greater in men.[7][8] Females are also more sensitive to the hormone.[9]
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I have been using HerbalT for almost two months. I noticed improvement in my sleep, energy and mood within 3-4 days. Prior to use, I had a sleeping disorder and would wake up tired in the morning. My energy level was low and the sexual desire needed a trigger. After using this product, my energy level has improved. I wake up in the mornings and feel that my system is default. My mood has also improved. I don’t think to feel/think negative and hardly stress over anything.

Ten healthy men aged around 24 years old spent 1 week sleeping for 8 hours per night at home, they then spent the next 11 nights in a lab. They slept for 10 hours per night for 3 nights, followed by 8 nights of restricted sleep, when they slept for only 5 hours. Doctors checked their blood every 15 to 30 minutes during the last night that they slept 10 hours, as well as on the sleep-restricted session.

Inaccurate or misinterpreted test results can either falsely diagnose or miss a case of testosterone deficiency. Your testosterone level should be measured between 7 am and 10 am, when it's at its peak. Confirm a low reading with a second test on a different day. It may require multiple measurements and careful interpretation to establish bioavailable testosterone, or the amount of the hormone that is able to have effects on the body. Consider getting a second opinion from an endocrinologist.

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Testosterone is an important hormone for both men and women. Even though it’s often associated with a man’s libido, testosterone occurs in both sexes from birth. In females, it plays a part in sexual drive, energy, and physical strength. In males, it stimulates the beginning of sexual development and helps maintain a man’s health throughout his life.

Hypogonadism (as well as age-related low testosterone) is diagnosed with blood tests that measure the level of testosterone in the body. The Endocrine Society recommends testing for suspected low T with a total testosterone test. It may be performed in the morning when testosterone levels tend to be highest in young men, although this isn't necessarily the case in older men. The test may be repeated on another day if the results show a low T level. (5)

Sharma, R., Oni, O. A., Gupta, K., Chen, G., Sharma, M., Dawn, B., … & Barua, R. S. (2015, August 6). Normalization of testosterone level is associated with reduced incidence of myocardial infarction. European Heart Journal, 36(40), 2706-2715. Retrieved from https://academic.oup.com/eurheartj/article/36/40/2706/2293361/Normalization-of-testosterone-level-is-associated