Testosterone is the main male hormone. 95% of it is produced in the testicles, under the influence of Luteinising Hormone (LH), which is released in spurts throughout the day from the pituitary gland. The signals are stronger in the early morning, which accounts for the higher testosterone levels and the spontaneous morning erections and increased libido. By late evening the levels can fall by 50 percent.

About 97% of testosterone in the blood is bound to a protein called Sex Hormone Binding Globulin (SHBG). These are not freely available, and serve as storage to maintain a steady supply for the tissues. Only the free testosterone is biologically active.

In addition to the testicular production, a smaller amount is created by the conversion of precursor steroid hormones such as androstenedione and androstenediol. However, if supplemented, androstenedione gets converted into more oestrogens than testosterone, and therefore there is not a sustained muscle enhancing effect, but often results in feminisation of the user.

Measurement of Testosterone

The Bio-T Test measures levels of bio-available testosterone, which is the portion either unbound, or bound to albumin, but not bound to SHBG.

The normal range reported on a laboratory report runs from about 290 to 900 ng/dl. However, it is the range for the whole population, covering men of all age groups and health statuses. They can be 80 or 20 years old; they can be chronically ill or very healthy; and they can be obese or thin. It is therefore not for any particular individual of a specific age. Unfortunately, most doctors think that if the test value falls in this range, then there is no problem.

Testosterone & Aging

Like the growth hormone, testosterone levels decline with age in healthy males. Total testosterone levels declined by about 5% per decade from the 30s to the 70s. Bio-available testosterone declines twice as fast, about 10% per decade, so that approximately 50% of men over 55 years old have levels below the lowest normal range for young men.

When testosterone drops to an absolute low level below 300 ng/dl, it is called hypogonadism. Virtually all men below this range exhibit the signs and symptoms. Relative deficiency in a man with symptoms and signs may be regarded as the andropause. Typical responses to low bio-available testosterone levels include:

  • Low sex drive and sexual performance
  • Emotional, psychological and behavioural changes
  • Decreased muscle mass
  • Loss of muscle strength
  • Increased upper and central body fat
  • Loss of height
  • Bone loss
  • Decreased energy
  • Frequent fatigue
  • Low red cell counts (anaemia)

Testosterone Replacement Therapy (TRT)

There is extensive evidence that replacing testosterone in hypogonadism is warranted, and there is no controversy that it should be treated. However, when the serum testosterone levels in a middle age or older man decline to a level above 300 ng/dl, but below the normal range in young men, and that person experiences clinical symptoms and signs consistent with androgen deficiency, he can benefit from a boost with TRT to the high end of normal or even above that. This is the use in andropause.

A number of studies have been done in healthy young men in whom doses of testosterone were given that raised their levels into the high adolescent range of 1000 to 2000 ng/dl. In all of these studies, lean muscle mass has increased and fat mass has decreased. Similar studies with lower doses have been done in moderately obese men; again, lean mass increased and fat decreased even more. Moreover, insulin resistance improved, triglycerides decreased, and energy increased. Many more studies have been published showing similar effects in older men over 65 with mildly low testosterone levels. The accumulating evidence shows that whenever you raise the testosterone level, no matter what the starting level, you get benefits in body composition, without any significant increase in adverse effects.

Once started, the medication should begin to reverse the signs and symptoms of andropause relatively quickly. However, just as andropause tends to have a slow and subtle onset, the reversal will also be slow and subtle, so it is important to stick with it for at least 3 months, and keep track of how the symptoms change. There is also the possibility that your starting dose may need to be increased.

Some problems may get better faster than others. You may notice improvement in your mood, thinking and concentration within a few short weeks, while other changes may take a little longer.

Treatment Options

There are a number of types of testosterone replacement treatments available. These include: pills to take by mouth, transdermal patches and gels applied to the skin, and injections. There are pros and cons to each method and you should discuss these choices with your doctor.

Alternatively, Human Chorionic Gonadotropin (HCG), which is a hormone that stimulates the testes to produce testosterone on their own, can be used. Only injection is available.

Potential Benefits of TRT

Basically the symptoms are reversed. They include:

  • Improvement in mood and sense of well-being
  • Increased mental and physical energy
  • Decreased anger, irritability, sadness, tiredness, nervousness
  • Improved quality of sleep
  • Improved libido and sexual performance
  • Potentially less bone degradation and an increase in bone density
  • An increase in lean body mass,
  • Decreased body fat, particularly around the waist
  • Increased muscle strength

Side Effects & Safety

Prolonged erection is a possible complication of testosterone replacement treatment. Occasional, if used at high doses, testosterone may be converted to oestrogens, and leads to enlarged breasts.

There is no evidence that testosterone may increase the risk of benign prostate enlargement, or prostate cancer. Nevertheless, it is recommended that elderly patients on testosterone treatment should have the prostate examined annually, together with ultrasound, and a blood test for prostate-specific-antigen (an indicator for prostate cancer) every 6 months.

There is conflicting evidence whether testosterone has more beneficial or adverse effects on the cardiovascular system.

Other concerns include its effects on sleep apnoea, hair growth and baldness, as well as too high a blood count.

In general, men with known prostate cancer, significantly enlarged prostates, or breast cancer should not receive TRT. There is also some question as to whether it should be used in men with sleep apnea.

Testosterone & Women

Just as for men, testosterone is important for maintaining lean muscle mass, assertiveness, and bone density in women. It is also important for warding off depression, increasing libido, and maintaining the health and sensitivity of the vaginal tissues. The difference is that women only need about a tenth of the circulating testosterone as men do.

Approximately 30% of a woman's testosterone is produced in the ovaries; the other 70 % is derived from conversion of adrenal androgen precursors, such as DHEA and androstenedione, both of which decline with age. So a woman will have a decline in her testosterone level as she ages. This is a gradual decline, and on average, there is a 50% drop in testosterone level between age 20 and 50, before menopause occurs.

When the ovaries are removed for other medical reasons, there is an abrupt drop in her testosterone production. The women may feel unwell, with drop in libido and weight gain, even when they are on adequate oestrogens replacement. Also, post-menopausal women may continue to lose their bone mass even on apparent adequate oestrogens replacement, but the bone density may be normalised when testosterone is added.

The free testosterone level can be measured and is probably on the low side. In the peri-menopausal period and after the menopause, in a woman with intact ovaries, restoring DHEA to youthful levels will often restore the testosterone levels adequately. In a woman who has had her ovaries surgically removed, it is usually necessary to start directly with bio-identical testosterone replacement. This is usually prescribed as a cream to be applied to the skin.

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