What is the Sex Hormone Binding Globulin (SHBG)?

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Sex hormone binding globulin is a carrier protein produced by the liver that plays a critical role in regulating the amount of the unbound steroids, testosterone, dihydrotestosterone (DHT) and estrogen, but mostly testosterone, in the blood. One of the most important reasons for performing a SHBG is an increase of the SHBG due to cortisol. Cortisol, which increases with stress, can increase your body fat and decrease your ability to lose weight.

Our Natural Bio Health clinics in Austin, San Antonio and College Station always test SHBG levels in our bioidentical hormone therapy, medical weight loss and natural diabetes treatment and prevention programs.

SHBG binds up your free testosterone.

What is bound up is not available for you to use. This is one reason we always test free testosterone (and SHBG). We need to know how stress, anxiety and even depression are affecting your body’s health. We need to know how much cash (free testosterone) your body has to use. If your SHBG blood test is high and your free testosterone is low, you have less testosterone to support your body.
Natural Bio Health SHBG

Why do I care about SHBG?

The level of this protein tells us a lot about your stress condition, your insulin condition and the effectiveness of your hormones. It can even tell us much about your health. See below.

Unbound hormones.

The meaning of unbound is the amount of hormone that is available to be used by the body and not tied up in a protein globulin. The unbound portion is called “free testosterone”, for instance, and it is the fraction that actually relieves symptoms and provides the health and quality of life benefits.

Unfortunately, classic medicine seems to focus on the fact that the SHBG, which can either be high or low, is not pertinent, that the total testosterone is all that matters. It is the free testosterone that will affect one’s symptoms. What is not recognized is that various physiological conditions cause shifts in the circulating levels of this high-affinity steroid-binding protein, and serum measurements can indicate several androgen abnormalities.

If you know what you are looking for and how to interpret SHBG, you can learn why an individual seems to be having trouble with their health – no matter what they do.

What can cause a high Sex Hormone Binding globulin in women?

  • Elevated estradiol levels over normal
  • Hyperthyroidism
  • Cirrhosis of the liver
  • Birth control pills
  • Extreme weight loss as in anorexia nervosa
  • Cigarette smoking
  • Any estrogen use as plant estrogens (phytoestrogens)
  • Increased conversion of testosterone to estrogen
  • Certain medications such a Dilantin ( a phenytoin)
  • Fibrocystic disease of the breasts
  • Any compromise of liver detoxification such as alcohol abuse, certain meds, heavy metals etc. can decrease liver capacity to excrete excess estrogens from the body.
  • Pregnancy
  • Stress with elevated cortisol

What causes low sex hormone binding globulin in women?

  • PCOS (polycystic ovarian syndrome)
  • Hypothyroidism
  • Diabetes/insulin resistance
  • Hyperprolactinemia
  • Excessive androgen activity

What causes high sex hormone binding globulin in men?

  • Elevated estradiol levels from conversion of testosterone
  • Hyperthyroidism
  • Aging
  • Extreme weight loss in anorexia nervosa
  • Certain medications as the Dilantin (a phenytoin)
  • Liver cirrhosis
  • Cigarette smoking
  • Any compromise of liver detoxification such as alcohol abuse, certain meds, heavy metals etc. can decrease liver capacity to excrete excess estrogens from the body.
  • Testicular cancer

What causes low sex hormone binding globulin in men?

  • Hypothyroidism
  • Diabetes/insulin resistance
  • Hyperprolactinemia
  • Excessive androgen activity

How do you use the information above?

Even though it is clear that a high SHBG can reduce or increase free testosterone and cause symptoms, it’s important examine the reason for the SHBG being high or low. Otherwise, the result will either be marginal or one can have side effects from too much testosterone or consequences from not treating the underlying problem.

A good example is that of stress when a patient has too much cortisol. This will raise the SHBG to very high levels and can create symptoms of testosterone deficiency. In this case you would have to address and treat the underlying stress and likely increase the total testosterone to influence the free testosterone in spite of being bound up by the SHBG.
Natural BioHealth SHBG levels

Women and Men are different.

Because of the marked difference in the total and free testosterone in women and men, a slight increase in SHBG in a woman will decrease her free testosterone. The total may be normal but the free very low. As a result, physicians tend to say that because of the normal total testosterone that the woman need not be treated, which is not true because of the low free testosterone.

Contrary results.

Why is it going up when I thought it would go down? For example, let’s look at diabetes or insulin resistance and stress. In this instance, the diabetes dominates the SHBG and it is usually low instead of being elevated as seen in patients with stress and increased cortisol.

Predictor of Diabetes.

At Natural Bio Health, I have also seen the FSH and LH elevated on a blood test secondary to stress, in spite of a normal estradiol. Women with low SHBG are more prone to develop diabetes as reported by Eric Ding, et all in the New England Journal of Medicine, September 2009. The reported study concluded that low circulating levels of sex hormone-binding globulin are a strong predictor of the risk of type 2 diabetes in women and men.

Have you had your SHBG tested? Call Natural Bio Health and test your levels.

Make an appointment with Dr. Feste to determine how your SBHG levels may be affecting your health and quality of life.


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Dr. Joseph Feste is a physician at Natural Bio Health.  He has been in practice for over 30 years.

Dr. Feste has written or contributed to numerous medical articles, has years of experience in treating infertility and PMS, and worked in the area in the area of women’s health for years. He served on the Board of Directors of the Woman’s Hospital of Texas and was Medical Director of the Premenstrual Syndrome Program at Woman’s Hospital. Dr. Feste has years of experience in the use of natural hormones, the treatment of PMS and endometriosis and the clinical application of hormone therapy for both men and women.