Testosterone levels naturally rise in response to sexual arousal and activity. Men with higher levels of testosterone usually have greater sexual activity. Older men need more testosterone for libido and erectile function. But it’s important to note that erectile dysfunction is often due to other conditions or medications rather than low testosterone levels.
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.[155] 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][155][161][162] 5α-Reductase is highly expressed in the male reproductive organs (including the prostate gland, seminal vesicles, and epididymides),[163] skin, hair follicles, and brain[164] and aromatase is highly expressed in adipose tissue, bone, and the brain.[165][166] As much as 90% of testosterone is converted into 5α-DHT in so-called androgenic tissues with high 5α-reductase expression,[156] and due to the several-fold greater potency of 5α-DHT as an AR agonist relative to testosterone,[167] it has been estimated that the effects of testosterone are potentiated 2- to 3-fold in such tissues.[168]
The testicles produce an enzyme called 11ßHSD-1 which protects your testosterone molecules from the effects cortisol.  During times of prolonged stress and chronically elevated cortisol, there simply is too much cortisol for 11ßHSD-1 to handle.  This results in testosterone molecules being destroyed inside the gonads before they even enter the bloodstream (8, 9).
These berries are known to improve your overall stamina and mood. But that’s not all, they also keep temperatures in the scrotum at the optimum level. The scrotum contains the testes which produce sperm. Higher temperatures tend to hamper the sperm production and decrease the volume that is released in a man’s ejaculate. They also promote sperm production by improving blood circulation and protecting against free radical damage.
As blood levels of testosterone increase, this feeds back to suppress the production of gonadotrophin-releasing hormone from the hypothalamus which, in turn, suppresses production of luteinising hormone by the pituitary gland. Levels of testosterone begin to fall as a result, so negative feedback decreases and the hypothalamus resumes secretion of gonadotrophin-releasing hormone. 
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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)
Hello there Abraham. My doc and you know each other well. We reside in Richmond, VA. Doc told me to inject my weekly Cypionate into sub fat for longer absorption, with reference you shared this info him with him. I have been his TRT patient for 10 years now. He is the best. I wont mention names. Please point me to a study showing the results of testosterone absorption from fat.
In summary, low testosterone levels are linked to the presence of numerous cardiovascular risk factors. Testosterone treatment acts to improve some of these factors, but effects may vary according to pre- and post-treatment testosterone levels, as well as other factors. There is little data from trials specific to aging males. Appropriately-powered randomized controlled trials, with cardiovascular disease primary endpoints, are needed to clarify the situation, but in the meantime the balance of evidence is that testosterone has either neutral or beneficial effects on the risk of cardiovascular disease in men. It is particularly important to define the effect of testosterone treatment on cardiovascular disease in view of its potential use as an anti-anginal agent.
If a young man's low testosterone is a problem for a couple trying to get pregnant, gonadotropin injections may be an option in some cases. These are hormones that signal the body to produce more testosterone. This may increase the sperm count. Hedges also describes implantable testosterone pellets, a relatively new form of treatment in which several pellets are placed under the skin of the buttocks, where they release testosterone over the course of about three to four months. Injections and nasal gels may be other options for some men.