Low level of testosterone on a blood test is quite a common finding in men. Unfortunately, many physicians often prescribe testosterone treatment as a knee jerk reflex, without thoroughly investigating the cause of the low testosterone test.
Before we discuss low testosterone, you need to understand the normal production of testosterone.
Normal Testosterone Production
Testosterone is normally produced by the testes in response to appropriate signals from the pituitary gland, a pea sized gland situated in the brain.
The pituitary gland itself is influenced by another gland sitting on top of it, the hypothalamus, which lies in close proximity to the limbic system, our emotions center in the brain.
Testosterone production, therefore can be influenced by a number of factors such as malfunction of the testes, diseases of the pituitary or hypothalmus gland or severe emotional distress.
Testosterone: Myths and Abuse
Recently a lot of physicians as well as patients are getting quite aggressive in checking blood testosterone level. Many people often mistakenly think testosterone to be some kind of "Miracle Cure" for their lack of energy. Some misguided people even consider it to be the the "Fountain of Youth!"
Hence, there is a lot of abuse of testosterone in the U.S. to the point that now testosterone comes under the controlled substance category in this country.
The fact is that testosterone is neither a "Miracle Cure" nor a "Fountain of Youth."
Actually testosterone treatment in those who are not low in testosterone can lead to serious health consequences. Therefore, testosterone treatment should be given only to those who are actually low in testosterone.
Symptoms of Low Testosterone
Symptoms of low testosterone include:
1. Lack of libido
2. Muscle weakness
3. Depressed mood
4. Weakening of bones
5. Hot flashes
As you can see, these are very generic symptoms. Many other diseases and often a lot of medications can give rise to the very same symptoms.
If there is a question that any of these symptoms may be due to low testosterone, the next step is to order a testosterone blood test.
Interpretation of Blood Test
The interpretation of a testosterone blood test is important. There are some pitfalls. An experienced physician such as an endocrinologist should be consulted if there is a question of low testosterone level.
Blood testosterone exists in three forms:
1. Testosterone bound to protein. (the protein is called Sex Hormone Binding Globulin, SHBG)
2. Free Testosterone
3. Bioavailable Testosterone
About 50% of the testosterone is bioavailable, only a fraction is free and the remaining approximately 50% is in the bound form and physiologically inactive.
The usual blood test for testosterone measures total testosterone (sum of all of the three forms).
Now consider this. In obese people, SHBG level is low. Consequently their bound testosterone (inactive form) is also low. As a result, their total testosterone is also low.
But their free and bioavailable testosterone is normal. Obviously, such a person will be harmed if placed on testosterone treatment.
Unfortunately, many physicians simply look at the total testosterone number and often start a person on testosterone treatment without checking the free or bioavailable testosterone.
Therefore, the blood test for free and/or bioavailable testosterone should be done in obese individuals and in any one with borderline low testosterone level.
Causes of Low Testosterone
If testosterone is actually low, the next step is to figure out the cause for the low testosterone.
The important point is to distinguish whether low testosterone is due to low signals from the pituitary gland or due to the malfunction of the testes. This requires the expertise of an endocrinologist.
The causes for low testosterone include:
1. High Prolactin level, which can be due a pituitary tumor
2. Andropause: A gradual decline in testosterone level with aging. This is synonymous to menopause in women. Hence the term, andropause. Compared to menopause, andropause occurs over a much longer period; a couple of decades.
3. Drugs such as Lupron, Spironolactone, Ketoconazole,
4. Habits: Marijuana, Alcohol, too much dietary intake of Soy.
5. Testicular disorders: mumps, radiation, surgical removal of both testes, Klinefelter's syndrome (a chromosal abnormality).
Treatment of Low Testosterone
Treatment of low testosterone depends upon its cause. For example, if it is due to a drug such as spironolactone, stopping the drug, if appropriate, is the right treatment.
In the same way, if testosterone is low due to high prolactin, then treating high prolactin is the appropriate treatment.
On the other hand, if a person with high prolactin gets placed on testosterone, then there is a chance that the primary cause of the problem, such a pituitary tumor causing high prolactin and consequently lowering the testosterone, will remain undiagnosed. An undiagnsoed and untreated pituitary tumor can have serious health consequences.
If the cause of low testosterone is not treatable, such as testicular damage from mumps, or low testosterone from andropause, then it is appropriate to start testosterone replacement therapy.
Testosterone replacement therapy can be carried in one of several ways:
1. Testosterone gel: Applied on the skin of the torso once a day.
2. Testosterone skin patches: Applied to skin of the torso once a day.
3. Testosterone scrotal patches: Applied to the skin of the scrotum, once a day.
4. Testosterone buccal preparations: Applied to the gum.
5. Testosterone injections: Given as a deep intramuscular injection, once a week.
Out of these, testosterone gel preparation is the most convenient method. However, testosterone gel is expensive. Therefore, many patients resort to taking a weekly shot of testosterone, which is pretty inexpensive.
Testosterone is also available in pill form. However, this oral form of testosterone can cause liver damage. Therefore, testosterone pills should Not be taken to replace low testosterone.
Monitoring Testosterone Level
It is important that the physician prescribing the testosterone treatment should also monitor blood level of testosterone to make sure that a patient gets an adequate level of testosterone and at the same time, does not suffer from its side-effects.
There is a high risk of side-effects from testosterone treatment if a person gets too much of testosterone.
Side-Effects of Testosterone Therapy
Side-effects from testosterone treatment include:
1. Growth of prostate cancer
2. Worsening of Benign Enlargement of the prostate.
3. Increase in red blood cells, which causes an increase in the viscosity of the blood, thereby increasing the risk for stroke.
4. Aggressive behavior
5. Retention of fluids
This article was written by Sarfraz Zaidi, MD, FACE. Dr. Zaidi specializes in Diabetes, Endocrinology and Metabolism.
Dr. Zaidi is a former assistant Clinical Professor of Medicine at UCLA and Director of the Jamila Diabetes and Endocrine Medical Center in Thousand Oaks, California.
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