|Total Testosterone, Free Testosterone and SHBG
Jun 4, 2000
I have been testing my Testosterone levels for over a year now, and mostly I have a low total testosterone index (+/- 300 ng/100 ml), but a 'normal' free testosterone index (+/- 10 ng/100 ml), with a sex hormone binding globuline of 0.54 ug/100ml. My questions: is it important to have a high total testosterone index? My doctor says it is low since I have a low shbg level, but I do not have to worry about it, since the total testosterone level is not used in the male body. My doctor says only the FREE testosterone level is used in the male body. Is this correct ??? And a second question: Will 100 mg Nandrolone Decanoate a week for 4 months suppress my own Testosterone, LH or FSH levels ??? Sincerely
Response from Dr. Hellerstein
Your doctor is right, that the tissues only use the free testosterone. However, an important practical issue is that total testosterone may be a more accurately measured value than the free testosterone and the SHBG in many hospital labs, just for technical reasons. So I still pay attention to the total. Also, the range of what is "normal" has no universal definition -- that is, every person has his own set point for what the testosterone level should be. A "normal" total or free testosterone may therefore be statistically normal, but not optimal for a given person.
Indeed, we published a study showing exactly this. Men with HIV infection, weight loss, and total testosterone in the low-normal range were given nandrolone at replacement doses, or a placebo. And the nandrolone group gained muscle, weight, and strength. This showed that low-normal values respond to androgen therapy, and therefore should be considered for such treatment.
So, looking at your numbers, I agree that you deserve some androgen treatment, both on the basis of the low free and the low-normal total testosterone values.
The one monkey wrench is your statement about being on nandrolone already. If this is true, then it explains the low testosterone measured. The body stops producing testosterone when external androgen is taken (it turns off like a thermostat that controls a furnace). The LH and FSH will be suppressed, as part of this. You really can say nothing about your actual testosterone status, until you have been off of all exogenous androgens for at least several weeks or even a few months.
Keep us posted!
Marc Hellerstein, M.D., Ph.D.
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