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Important in men and women


Testosterone Definition:

  • Testosterone is a steroid hormone belonging to the androgen group of hormones. It is found in both males and females and in mammals.
  • Testosterone is primarily secreted from the testes of males and from the ovaries of females. Small amounts are also secreted by the adrenal glands.

It is the main male sex hormone and is an anabolic steroid.

Testicular Anatomy

1 Epididymis 

2 Head of epididymis

3 Lobules of epididymis

4 Body of epididymis

5 Tail of epididymis

6 Duct of epididymis

7 Deferent duct (ductus deferens or vas deferens)


Often subtle - a slow deterioration


Diagnosing low testosterone: Look at the man or go by the numbers?

  • Often doctors will treat the numbers and not the patient.
  • It is important to look at the symptoms of low testosterone [T] or low-T and not rely on 'magic' figures which may be wrong or may not be proportional to the severity of symptoms being felt by the man.
  • If you have symptoms of low-T but your results are low-normal do you have low-T --- the answer is maybe.

Delaying treatment makes no sense in the light of new findings [see below]

  • Delaying treatment when we now know the adverse clinical consequences of low testosterone makes no sense.
  • Change in medical practice is often like a lumbering elephant - slow. Yet lives are at stake.
  • A study published by The Endocrine Society which was a longitudinal 18 year study funded by the National Institute on Aging and the American Heart Association made the statement that men over 50 may not live as long if they have low testosterone29.
  • There was a 33 percent greater risk of death during the next 18 years in men with low testosterone levels when compared with men with higher testosterone levels. This difference in risk was independent of smoking, alcohol intake and level of physical activity or pre-existing diseases such as diabetes or heart disease29.

An enlightened statement about testosterone use in adults comes from the American Association of Clinical Endocrinologists:

"Hypogonadism is defined as a free testosterone level that is below the lower limit of normal for young adult control subjects. Previously, age-related decreases in free testosterone were accepted as “normal,” but this concept has been challenged.....Patients with borderline testosterone levels warrant a clinical trial of testosterone23."

Therapeutic Trial or Clinical Trial of Testosterone

  • The symptoms of low testosterone can be the symptoms of aging or due to other processes.
  • Thus treating with testosterone may or may not have the desired effect but will be the only way to find out and to resolve that 'maybe' issue.
  • However, if low testosterone is the cause of decreased libido or lethargy or a clouded mind or decreased exercise capacity or recovery from exercise - then testosterone replacement can make a dramatic difference in a man's life.
  • Low testosterone has been implicated in increased diabetes26, heart attacks26, decreased longevity26, osteoporosis26, increased cardiovascular risk26 and even more aggressive prostate cancer27. However the primary reason to treat is to alleviate the symptoms of testosterone deficiency as described below.

Desire, Erection, Ejaculation: Testosterone is involved in all 3 areas

Decreased Libido

  • A decreased libido is the hallmark of low testosterone.
  • Libido is your sex drive and your desire to have sex with your partner.
  • This could be either a decrease in the 'hunger' or passion for sex or simply that the frequency or intensity of sex has decreased.

Erectile Dysfunction

  • You may not be able to achieve an erection [Erectile Dysfunction or ED].
  • This is the second most common symptom of
    low-T 26.
  • If you need to stay focused or to concentrate greatly during sex to simply maintain your erection, then low testosterone may be to blame and a therapeutic trial may be worthwhile.

Difficulty achieving an orgasm, decreased intensity & decreased ejaculatory fluid

  • Low-T may also lead to difficulty achieving orgasm.
  • The intensity of the orgasm may be lower.
  • Ejaculation may occur faster than expected or liked.
  • Longer stimulation may be required to achieve orgasm.
  • The amount of ejaculatory fluid may also be diminished with low-T.

Central Adiposity [troublesome fat in your midsection]

  • Increased central adiposity- a slow but steady increase in fat gain around the midsection [in men and women] which can be difficult to shift in spite of diligent exercise and diet.
  • Abdominal fat increases your risk for insulin resistance, the metabolic syndrome, diabetes, systemic inflammation, cardiovascular disease and hypertension -- these are deadly consequences of increased abdominal fat and are factors often ignored in medical decision making with regard to testosterone replacement in men.
  • Fatty breast tissue may also develop as a result of low-T and conversion of testosterone to estrogen by aromatase in abdominal fat.
  • The fat in this distribution can make things worse for a man. Fat in this area can convert androgens [male hormones like testosterone] to estrogen the female hormone - yes, this is right, a man can increase production of estrogen through an enzyme called aromatase in this body fat. This worsens sexual dysfunction and lowers testosterone increasing cardiovascular risk as well. Increased estrogen in middle aged men has also been implicated in the aetiology of prostate cancer.

Other non-sexual symptoms

  • Fatigue - numerous other reasons need to be excluded.
  • Decreased motivation.
  • Loss of muscle strength and muscle mass: Inability to lift weights you were capable of previously lifting and poor recovery times after exercise.
  • Low bone density [osteopenia and osteoporosis] - numerous studies have shown that low testosterone is associated with loss of bone mass and that testosterone treatment can reverse this. Have bone density tested prior to treatment.
  • Low red blood cell count [anaemia] may occur with low testosterone levels as testosterone stimulates the production of red blood cells in the body. However, other causes such as low iron, vitamin B12 and folic acid need to be assessed as causes of anaemia and tests to exclude genetic causes such as thalassaemia need to be considered as well. But when all else has been excluded, the finding may just be a low testosterone level due to decreased red cell production dependent on testosterone. The reverse of anaemia may also occur with T treatment. If you are on T treatment and increased red cell production has occurred then donating blood on a regular basis may be all that is necessary to keep this under control.
    With regard to erythropoiesis by androgens, this study stated: 

    "It is concluded that two mechanisms underlie the stimulating actions of steroids on erythropoiesis; one through the production of erythropoietin and the second involving a more direct influence on the blood-forming tissues."

    So testosterone works by both increasing erythropoietin and in the bone marrow to enhance the effects of erythropoietin.28

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Infertility, Sperm Count, DHT & Hair Loss

Depends on where the T is coming from or applied

  • Initially for treating testosterone deficiency, scrotal patches were used. The scrotum is the sac of skin surrounding the testes.
  • Scrotal skin is rich in 5α-reductase the enzyme that converts testosterone to dihydrotestosterone [DHT] and for this reason using a scrotal patch or applying testosterone gel to the scrotum will result in high circulating DHT levels.23
  • The problem with DHT is that there is the risk of hair loss in men genetically susceptible to this problem.
  • The good news is that patches applied to the skin [recommended not over bony prominences] or gels applied to the skin do not produce elevations in DHT and thus will not be a problem with regard to hair loss26.
  • Testosterone supplementation with gels, patches or injections have the potential to lower sperm counts. The reason for this is that the negative feedback mechanism to the pituitary shuts down LH production which normally stimulates the Leydig cells in the testes themselves to produce testosterone. This effectively ‘shuts down’ the testes and they then atrophy [shrink in size] with diminished to almost no sperm production.
  • According to Dr Abraham Morgentaler, ‘alternative treatments are available to stimulate higher testosterone production in the testicles, which may lead to greater sperm production in some men.26
  • Clomiphene citriate [Clomid] is a non-steroidal treatment that increases testosterone production within the testes and thus less likely to interfere with sperm counts and infertility.

Hormone & Hormone Metabolite References

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Hormone & Hormone Metabolite References


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An Evidence-Based Approach to Dietary Phytochemicals

Jane Higdon, Ph.D.

Testosterone For Life

Prof Abraham Morgentaler - Harvard University