SHBG (Sex Hormone Binding Globulin): High or Low Meaning
Also known as: Sex hormone binding globulin, SHBG blood test, SHBG test
SHBG (sex hormone binding globulin) is a protein made mostly by the liver that binds testosterone and estradiol in the bloodstream, controlling how much of each hormone is free and biologically active. A normal SHBG is roughly 10–57 nmol/L in adult men and 18–144 nmol/L in premenopausal women, though ranges vary by lab and rise with oral contraceptive or estrogen use. High SHBG can lower free testosterone even when total testosterone looks normal, while low SHBG — often linked to obesity, insulin resistance, or PCOS — can raise free testosterone; either pattern is interpreted by a clinician alongside your total and free hormone levels.
SHBG normal range
| Category | Range (nmol/L) |
|---|---|
| Adult men | ~10–57 nmol/LReference ranges vary by lab and assay |
| Adult premenopausal women | ~18–144 nmol/LHigher on oral contraceptives, in pregnancy, or with other estrogen use |
| High | Above the lab's reference rangeLowers free (bioavailable) testosterone and estradiol |
| Low | Below the lab's reference rangeRaises free (bioavailable) testosterone and estradiol |
Reference ranges vary by laboratory. Use the range printed on your own report as the definitive comparison.
What high SHBG can mean
- Hyperthyroidism (overactive thyroid), which increases the liver's SHBG production
- Estrogen exposure — oral contraceptives, hormone therapy, or pregnancy
- Liver cirrhosis or other chronic liver disease
- Older age, especially in men, since SHBG tends to rise gradually with age
- Low body weight or anorexia nervosa
- The practical effect is less free (bioavailable) testosterone or estradiol — in men this can cause fatigue, low libido, or other low-testosterone symptoms even when total testosterone looks normal
What low SHBG can mean
- Obesity and insulin resistance — among the most common causes; low SHBG is also associated with a higher risk of type 2 diabetes over time, though it isn't used as a stand-alone screening or diagnostic marker for diabetes
- Polycystic ovary syndrome (PCOS) in women — low SHBG raises free testosterone, contributing to acne, excess hair growth, and irregular periods
- Hypothyroidism (underactive thyroid)
- Use of androgens, anabolic steroids, or high-dose glucocorticoids
- Nephrotic syndrome (protein loss through the kidneys)
- Growth hormone excess (acromegaly)
- The practical effect is more free (bioavailable) testosterone or estradiol than the total hormone number alone would suggest
What to do about an abnormal result
- SHBG is rarely interpreted alone — it's usually ordered alongside total testosterone (and sometimes estradiol) to calculate or estimate the free, active hormone level.
- Compare your value to the range on your own report; SHBG reference ranges vary more between labs than most hormones, and rise substantially with pregnancy or estrogen use.
- If your total testosterone is 'normal' but you have symptoms of low testosterone, ask your doctor whether a high SHBG (and correspondingly low free testosterone) could explain it.
- A low SHBG found alongside other findings like weight gain or irregular periods is worth discussing as a possible marker associated with insulin resistance or PCOS, not a stand-alone diagnostic test for either.
- Don't self-diagnose from one number — SHBG is interpreted by a clinician alongside your total and free testosterone or estradiol, thyroid function, and symptoms.
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Frequently asked questions
What does high SHBG mean?
High SHBG means more of your testosterone and estradiol are bound and inactive, which lowers the free (bioavailable) hormone level even if your total testosterone or estradiol looks normal. Common causes include hyperthyroidism, estrogen use (including oral contraceptives or pregnancy), liver disease, older age, and low body weight. In men, this pattern can cause low-testosterone symptoms despite a 'normal' total testosterone result.
What does low SHBG mean in females?
In women, low SHBG is most often linked to obesity, insulin resistance, or polycystic ovary syndrome (PCOS). Because SHBG normally binds testosterone, a low level lets more free testosterone circulate, which can contribute to acne, excess hair growth (hirsutism), and irregular periods — hallmark PCOS symptoms. Low SHBG is typically interpreted alongside free and total testosterone, insulin/glucose levels, and your cycle history, not diagnosed from the SHBG number alone.
What is a normal SHBG level?
A normal SHBG is roughly 10–57 nmol/L in adult men and 18–144 nmol/L in premenopausal women, though exact cutoffs vary by lab and assay, and levels rise substantially with pregnancy or estrogen-containing medication. Because the range is wide and lab-dependent, compare your result to the reference range printed on your own report.
Does high SHBG cause low testosterone symptoms?
It can. SHBG binds most of the testosterone in your blood, so a high SHBG level leaves less testosterone in the free, active form your tissues can actually use — even if your total testosterone result is within the normal range. This is one reason some people with 'normal' total testosterone still have symptoms like fatigue or low libido, and why doctors sometimes calculate or directly measure free testosterone alongside SHBG.
Related biomarkers
Sources
This page draws on the following authoritative references.
- Prediction of Insulin Resistance and Impaired Fasting Glucose Based on Sex Hormone-Binding Globulin Levels in Polycystic Ovary Syndrome — International Journal of Endocrinology
Medically reviewed by Antonieta Rueda, MD and Kyle R. Toth, MD · Last reviewed July 22, 2026
This article is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or your lab results.