Confused about what affects SHBG levels

Discussion in 'Men's Health Forum' started by zadok, May 2, 2006.

  1. #1

    zadok Junior Member

    I am a bit confuesed about how testosterone and androgens affect SHBG levels as I have read conflicting opinions. This is cut from this post:

    "What determines how much free testosterone we have at any given time is an enzyme known as Sex Hormone Binding Globulin -- also known as SHBG. The more you have, the more testosterone will be kept in a bound state. The pesky little chemical is also the reason some guys hardly grow even while on high dosages of steroids. The more exogenous testosterone that enters your body, the more SHBG the body will produce. It's our body's way of maintaining homeostasis. It's also another reason why taking supraphysiological dosages of steroids isn't the wisest choice. The more you take, the more it binds, so at a certain point, most of it is just wasted....

    This information also bears out reports that many pros don't take quite as much as one may think. The presumption is that in order to achieve that level of muscularity they need insane dosages but it's more likely that these lucky individuals simply have more favorable androgen receptors and lower SHBG than the average bodybuilder. To put it in comparative terms, if you were to take 1000 mgs of testosterone and your "free" T is 30, yet someone else takes only 500 mgs of testosterone (or none at all) and his free T is 40, he's going to kick your butt in a competition. It isn't fair, but that's the way it is.

    Instead of taking more exogenous testosterone, it would make more sense to allow more of the testosterone we already have to become unbound. Unfortunately, the amount of SHBG you have is determined mostly by genetics and those individuals who have a lot of it will probably always remain "hardgainers." SHBG also increases with age. In spite of these drawbacks, there have been some fascinating findings that may be able to tilt the odds in your favor."

    This post maintains that Higher testosterone levels will cause SHBG levels to rise.

    This is a post by Marianco:

    "Sex Hormone Binding Globulin (SHBG) production by the liver depends on the summ effect of promoting and inhibiting factors.

    SHBG promoting factors include: estrogens, thyroid hormone, substances which speed up liver production (including several anticonvulsants), liver disease, etc.

    SHBG inhibiting factors include: testosterone, DHEA, insulin, DHT, growth hormone, etc.

    One test for free estradiol (E2) is a saliva test for estradiol"

    In this post it indicates that Testosterone will supress SHBG levels.

    Also apart from SHBG relationship to testosterone, what about other androgens like anabolic steroids (injectable not oral) I have read that these will supress SHBG but I have also read vice-versa?

    Can anybody shed some light on this?

  2. #2

    jboldman Junior Member

    marianco's post is correct.

  3. #3

    marianco Doctor of Medicine

    You guys are getting better all the time. :)
  4. #4

    DLMCBBB Junior Member

    Sounds strikingly similar to Animal's claim!

  5. #5
    Michael Scally MD

    Michael Scally MD Doctor of Medicine

    AAS suppress SHBG. TRT at physiological levels will not affect SHBG significantly. However, it has been conclusively and definitively shown that AAS suppress SHBG. It is not unusual to see SHBG levels close to zero (0) for individuals on AAS (particularly orals).

  6. #6

    zadok Junior Member

    Thanks heaps for the reply Mike.

    When SHBG goes so low then does 'free Estrogen' come up very high? It seems that that maybe that is what am suffering from now. My TT is high normal, FT is v low and E1, E2, E3 low-normal. SHBG is <5nmol/l (17-70). I could post all my results and ranges if you want but have done many times before. I have a history of oral and injectible streroid abuse. However I stopped taking these substances over 9months ago. SHBG still has not come up at all

  7. #7

    marianco Doctor of Medicine

    SHBG levels, estrogen, testosterone, thyroid

    Sex Hormone Binding Globulin (SHBG) extends the duration of action of testosterone and estrogens. When SHBG is low, more estrogen and testosterone can be free. However, free estrogen and testosterone can then be quickly destroyed. For example, testosterone has a half-life of about 10-100 minutes depending on the reference. Thus a person many end up with lower overall free estrogen and testosterone when SHBG is low.

    SHBG, itself, can bind to its own receptors (SHBG-receptors) on cell membranes. Once bound to the receptors, it can then bind testosterone, estrogens, DHT, etc., which then triggers the production of proteins including androgen receptors, or trigger other changes in cell function. It may be important to have adequate SHBG to have the full effect of testosterone and estrogens.

    Since low estrogen levels means one may have impairment in SHBG production, outside of adding more estrogen to the body, the one other hormone system to examine is the thyroid hormone system. Thyroid hormone can increase SHBG. So if SHBG is low, it may be important to check Free t3 to determine its activity.

    Interestingly, thyroid hormone (T3 is the active version) also stimulates testosterone and other steroid hormone production in the testes Leydig cells.

    The testes Leydig cells also produce Thyrotropin releasing hormone (TRH) - a function more commonly thought to be of the hypothalamus. Whether or not it can get into the brain and do its numerous mindboggling effects on behavior is not clear.

    TRH from the hypothalamus increases TSH, which then increase thyroid hormone production. TRH also increases prolactin production.

    TRH is also produced in the pancreas during hypothyroidism; and in other parts of the gastrointestinal system where it affects gastric motility, acid secretion, absorption of sugars.
  8. #8

    zadok Junior Member

  9. #9

    marianco Doctor of Medicine

    Interesting thread.

    If free estradiol levels are higher when one has low SHBG, then the free estradiol would be expected to raise SHBG, which then would reduce the free estradiol levels.

    Total testosterone is high normal.
    SHBG is low.
    But despite TRT: free testosterone is low, estradiol is low-normal, estriol is low-normal and estrone is low-normal.

    If estradiol is low-normal, what is the chance of having a very high free estradiol? One can check a saliva estradiol level to find out.

    What are other factors that have not been examined which keeps SHBG low? For example, I would look for suboptimal thyroid function (free t3, free T4, TSH), insulin-resistance/diabetes (fasting glucose, hemoglobin A1c, insulin), etc.
  10. #10

    zadok Junior Member

    Thanks for the reply.

    Where i live they dont do any saliva testing. What are the ones like that I can buy off the internet? For Estradiol they are around $30. I have heard that saliva tests are inaccurate? SWALE didnt like them for some reason.


  11. #11

    DLMCBBB Junior Member


    Is there any supportive "evidence" being published for saliva tests, those who do not profit from the "evidence?"

  12. #12

    zadok Junior Member

    Probably quite high since 30-40% of E2 normally binds to SHBG (correct me if i am wrong) then with very low SHBG, like <5nmol/l (17-70). I think the chances of free estradiol being very high is quite possible.
  13. #13

    marianco Doctor of Medicine

    Saliva tests vs. Blood tests.

    Is there any supportive "evidence" published for the accuracy of ANY LAB TEST by those who do not profit from the "evidence"?

    I think there would be few if any published studies by those who do not profit from the "evidence" for any lab test - blood, urine, saliva, etc.

    It would be prohibitably expensive for someone who does not profit from the "evidence" to do such testing.

    In medicine, I think the bulk of the studies are done by those who stand to profit from the "evidence". The reason is that there would be little incentive to spend so much money if one is not personally vested from profiting from the results.

    Case in point are studies on medications. A single study may cost millions of dollars. Who has the money to do the studies other than the big drug companies? Hardly anyone. This is why once a medication goes generic, usually no further studies are done - no matter how useful the studies would be.

    Researchers publish to make a name for themselves so that they can keep their careers. When I was in a university, it was called "Publish or Perish". If a researcher doesn't publish, they may get laid off. There is enormous pressure on professors to publish. This has led to many of the erroneous findings in the literature.

    In clinical practice, we make the assumption that lab tests have some high degree of accuracy. We base that assumption on how the test results correlate with the history and physical exam over the course of our careers.

    In medicine, a rule of thumb is that 90% of the diagnosis can usually be made from the history and physical. Lab tests are suppose to confirm the clinical findings - to confirm the diagnosis or to help hone in on the diagnosis from a selection of diagnoses (the differential diagnosis).

    Lab tests, however, can be wrong. For example, the universally used TSH for thyroid status can be very wrong many times. Yet, it continues to be used by most physicians dogheadedly.

    Ultimately, each physician has to decide on the utility of any particular lab test based on how useful the lab test is in confirming the clinical impression.

    In regard to saliva tests, I have found the saliva test for cortisol and DHEA-s to be highly useful. They corrrelate very well with the clinical findings and the blood test results. The utility of the other hormone saliva tests remains to be seen since I don't have much experience yet with them. But other clinicians have found them highly useful.
  14. #14

    hackskii Member

    Wow, impressive post.
  15. #15

    DLMCBBB Junior Member

    I would like to add, study participants may not be representative of people who will be likely to take the drug in real life. Study participants may be younger or healthier, and elderly or sick people do not respond to drugs in the same way their younger, healthier counterparts do.

    Guys remember the infamous JAMA study on Andro?

    Also, considering the potential for huge profits in drug sales, the pharmaceutical industry’s funding of research has been shown to buy biased results that, in the opinion of some, resemble paid advertising more than scientific research. Additionally, even in the most scientifically-sound studies, group statistics do not apply to individuals, because people aren't test subjects, but are complex and dynamic individuals. Furthermore, contractual agreements between clinical researchers and drug companies can take away the scientific independence of researchers and tie their hands from freely reporting unfavorable data.

    Also, the very treatment a patient needs may never be researched. For instance, natural substances cannot be patented and thus don't have the potential to produce the huge profits necessary to recover research costs, which are routinely in excess of $300 million, like Marciano noted in the previous post.

    The reliability of scientific research is regularly questioned, you can see that by an array of bro's just here on Meso. Many drugs have passed rigorous scientific studies and clinical trials and gained FDA approval only to be taken off the market because of side effects that became apparent only when the drug was given to “real” patients. Indeed, there is less risk when taking “tried-and-true” drugs that have withstood the test of time than there is from taking newer drugs that have been in the marketplace for only a short time.

    Practicing doctors can end up being spoon-fed whitewashed research data, unwittingly becoming the third “blinded” group. Historically, most major advances in medicine have not resulted from scientific research, but instead from reasoning of individual physicians’ basic observations of the patient and his disease. Throughout history, the real movers and shakers in medicine have been free-thinking individuals who were unbound by the influence of research money and restrictive political-based regulations. What’s a patient to do? Cautiously walk, don't run, toward the latest research. Get second, and third, opinions when needed. Go to physicians who practice integrative medicine, who utilize treatments other than drugs, who get to know their patients as individuals, and who value both the science and the art of medicine.


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