SHBG blood test: what sex hormone-binding globulin does, normal levels, and what high or low SHBG means for testosterone
Sex hormone-binding globulin (SHBG) is the liver-made protein that carries most testosterone and estradiol in the blood. Only the hormone not bound to it is free to act, so SHBG decides how a total testosterone result should be read: high SHBG can hide a low free level behind a normal total, low SHBG the reverse. Typical adult ranges are about 16.5–55.9 nmol/L in men and 24.6–122 nmol/L in women, and it is usually drawn alongside total testosterone.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
The short answer
SHBG is measured with a standard blood draw; no fasting is needed. A typical reference range is 16.5 – 55.9 nmol/L (male, age 18+; more bands below). At TestWell it's $69.99 all-in as Testosterone, Free & Total + SHBG, results in 3–5 business days, drawn at Quest or Labcorp. An out-of-range result is a prompt to look closer, not a diagnosis.
- Units
- nmol/L
- Sample
- Blood draw
- Fasting
- Not required
- Results
- 3–5 business days
- Price
- $69.99
- Labs
- Quest or Labcorp
What does an SHBG test measure?
SHBG is a glycoprotein produced mainly by the liver. It binds testosterone and dihydrotestosterone tightly and estradiol somewhat less tightly, and while a hormone is bound to it, that hormone cannot enter cells. In a typical man about 40–60% of testosterone is bound to SHBG, most of the rest is loosely bound to albumin (which tissues can still use), and only 1–3% is free. Women have roughly twice the SHBG concentration, which is one reason their free testosterone is so much lower than the total suggests.
The test measures SHBG concentration in nanomoles per liter (nmol/L). On its own the number is rarely the point; its value is in interpreting total testosterone and, through a calculation, estimating free and bioavailable testosterone. Laboratories use the Vermeulen equation — total testosterone, SHBG and albumin — to produce the 'calculated free testosterone' seen on many reports, and the same math is available in TestWell's free testosterone calculator.
SHBG Reference Range
These are the typical adult reference ranges used by major US labs. Your report will include the specific range used by the lab that processed your sample.
| Population | Range |
|---|---|
| Male, age 18+ | 16.5 – 55.9 nmol/L |
| Female, age 18+ | 24.6 – 122 nmol/L |
Reference ranges are educational. Always interpret your result with the specific range printed on your lab report and discuss anything outside the range with a clinician.
Have a result in hand? analyze it with your AI assistant using these reviewed ranges, or run it through our explainer. Tools: look up another marker's range · convert lab units · free testosterone calculator
What is a normal SHBG level?
Adult reference ranges are wide because SHBG varies with age, weight, sex hormones and thyroid status. Representative ranges from a major US laboratory are 16.5–55.9 nmol/L for men and 24.6–122 nmol/L for women; children and pregnant women have different ranges. SHBG rises gradually with age in men, which is a large part of why free testosterone falls faster than total testosterone in older men.
There is no ideal SHBG. A level anywhere in the range is compatible with normal hormone function; what matters is the combination with total testosterone and symptoms.
| Total testosterone | SHBG | What it often means |
|---|---|---|
| Normal | High | Free testosterone may be low despite a normal total — the classic reason a man with symptoms has a 'normal' result. Calculated free testosterone settles it. |
| Low | Low | Common in obesity and insulin resistance; free testosterone may be closer to normal than the total suggests. |
| Normal or high | Low (women) | More free testosterone reaching tissues — a pattern seen in PCOS with acne, hirsutism or irregular periods. |
| Low | High | Free testosterone is genuinely low; hypogonadism evaluation proceeds on the total and free values together. |
What causes high SHBG?
Anything that stimulates the liver to make more SHBG raises the level, and the list is dominated by estrogen, thyroid hormone and the changes of aging:
- Aging — SHBG rises steadily through adult life in men.
- Oral estrogens — combined oral contraceptives and oral menopausal hormone therapy can double or triple SHBG; transdermal estrogen has much less effect.
- Hyperthyroidism — thyroid hormone is a strong stimulus to SHBG production, and a raised SHBG is sometimes the clue to an overactive thyroid.
- Liver disease, including cirrhosis and hepatitis.
- Low body weight, low insulin levels, anorexia nervosa and very low-calorie diets.
- Anticonvulsants such as phenytoin and carbamazepine, and some HIV medications.
- Pregnancy, which raises SHBG several-fold.
- Growth hormone deficiency and, occasionally, an inherited variant of the SHBG gene.
What causes low SHBG?
Low SHBG is most often a metabolic signal. Insulin suppresses SHBG production, so the conditions that raise insulin lower SHBG — and a low SHBG is itself associated with a higher risk of developing type 2 diabetes:
- Obesity, insulin resistance, metabolic syndrome and type 2 diabetes — the most common causes in both sexes.
- Polycystic ovary syndrome (PCOS), where low SHBG amplifies the effect of modestly raised androgens.
- Hypothyroidism.
- Androgens and anabolic steroids, including testosterone therapy itself, and progestins with androgenic activity.
- Glucocorticoids (prednisone and similar) in sustained use.
- Growth hormone excess (acromegaly) and high prolactin.
- Nephrotic syndrome, where protein is lost in the urine.
- Cushing's syndrome.
Why SHBG changes what your testosterone result means
The Endocrine Society's hypogonadism guideline recommends measuring SHBG — and calculating free testosterone — whenever a man's total testosterone sits near the lower limit or when a condition that alters SHBG is present: obesity, diabetes, older age, thyroid disease, liver disease, HIV, nephrotic syndrome, or use of the medications listed above. The reason is simple arithmetic. A man with a total testosterone of 350 ng/dL and an SHBG of 25 nmol/L has a comfortably normal free level; the same total with an SHBG of 80 nmol/L can put free testosterone below the range, with symptoms to match.
The same logic runs the other way in women being evaluated for androgen excess. A total testosterone at the top of the female range with a low SHBG means substantially more free androgen than the same total with a high SHBG — which is why the free androgen index or calculated free testosterone, both of which depend on SHBG, are used in PCOS evaluation.
Direct free testosterone immunoassays are unreliable, which is why guidelines prefer either equilibrium dialysis (expensive, slow) or a calculation from accurately measured total testosterone and SHBG. Drawing the two together, in the morning, is the practical standard.
How to get an SHBG test
SHBG is a routine blood test at Quest and Labcorp, available through a clinician or directly through TestWell, where it is sold alone and bundled with total and free testosterone. Draw it in the morning together with total testosterone — testosterone peaks early in the day and fasting removes meal effects, and SHBG only helps interpretation when the two come from the same sample. Fasting is not required for SHBG itself.
Tell the ordering clinician about oral contraceptives or estrogen, thyroid medication, anticonvulsants, glucocorticoids and any testosterone or anabolic steroid use, since each moves SHBG in a predictable direction. Results are compared within the same laboratory; a change in SHBG between labs can be assay rather than biology.
What does a high SHBG mean?
High SHBG binds more testosterone and estradiol, lowering the free, active fraction — so total hormone levels can look normal while free levels are low. Common causes are oral estrogens (including birth control pills), hyperthyroidism, liver disease, aging in men, low body weight, anorexia and some anticonvulsants. Free testosterone is the number to look at when SHBG is high.
Common causes of a high SHBG
- Oral contraceptives and oral estrogen therapy
- Hyperthyroidism
- Liver disease (cirrhosis, hepatitis)
- Aging in men, low body weight, eating disorders
- Anticonvulsants, HIV infection
- Pregnancy
Ordered from most to least common.
Symptoms that can go with it
- Low libido, fatigue if free testosterone is reduced
What clinicians usually check next
- Free testosterone (calculated or measured) rather than total
- TSH and liver panel
- Medication review
Follow-up tests at TestWell: TSH (Thyroid Stimulating Hormone) ($26.99), TSH + Free T4 ($27.99).
My total testosterone is normal but I have low-T symptoms. Could SHBG explain it?
Yes — high SHBG lowers free testosterone. Ask for a calculated free testosterone using the measured SHBG.
Educational only — not a diagnosis. A single result outside the range is a prompt to look closer with a clinician.
What does a low SHBG mean?
Low SHBG is strongly associated with insulin resistance — excess weight, type 2 diabetes, fatty liver, PCOS — and with hypothyroidism, anabolic steroid or testosterone use, and glucocorticoids. It raises free testosterone relative to total, which contributes to acne and hair growth in women with PCOS. Low SHBG is also an independent marker of future type 2 diabetes risk.
Common causes of a low SHBG
- Insulin resistance, obesity, type 2 diabetes, fatty liver
- PCOS
- Hypothyroidism
- Androgens: testosterone therapy, anabolic steroids
- Glucocorticoids, progestins, growth hormone excess
Ordered from most to least common.
Symptoms that can go with it
- Women: acne, excess hair, irregular periods
- Men: often none; reflects metabolic risk
What clinicians usually check next
- Fasting insulin, A1c, lipid panel
- TSH
- Free testosterone to interpret hormone symptoms
Follow-up tests at TestWell: Lipid Panel ($24.99), TSH (Thyroid Stimulating Hormone) ($26.99), TSH + Free T4 ($27.99).
Is low SHBG bad?
It's a metabolic warning sign more than a problem in itself — it tracks insulin resistance and predicts diabetes risk. Weight, activity and blood-sugar improvements raise it.
Educational only — not a diagnosis. A single result outside the range is a prompt to look closer with a clinician.
How do you get a SHBG test?
Order online, a licensed physician reviews the requisition, and you walk into a nearby lab for the draw. SHBG is available on its own or inside these panels — panels cost less per marker when you want the fuller picture.
| Option | Includes | Price |
|---|---|---|
| Testosterone, Free & Total + SHBG | This marker only | $69.99 |
Quest vs. Labcorp for SHBG: which lab should you pick?
Both are CLIA-certified national labs and the result is clinically equivalent, so pick whichever location is closer. Your report will print that lab's own reference range, which can differ slightly from the table above.
| Lab | Available | Price |
|---|---|---|
| Quest Diagnostics | Yes | $69.99 |
| Labcorp | Yes | $94.99 |
| BioReference (NY & NJ) | No | — |
Need help choosing a location? Use the lab finder to see draw sites near your ZIP.
Keep reading
Guides, symptom pages and preparation notes that involve shbg.
Sources
- Mayo Clinic Labs →
- MedlinePlus (NIH) — SHBG Blood Test →
- Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 2018;103:1715–1744. →
- Vermeulen A, Verdonck L, Kaufman JM. A critical evaluation of simple methods for the estimation of free testosterone in serum. J Clin Endocrinol Metab 1999;84:3666–3672. →
- Goldman AL, et al. A Reappraisal of Testosterone's Binding in Circulation: Physiological and Clinical Implications. Endocr Rev 2017;38:302–324. →
Related Hormones biomarkers
Markers commonly tested alongside SHBG.
Frequently asked
What is a normal SHBG level?
Representative adult ranges are about 16.5–55.9 nmol/L for men and 24.6–122 nmol/L for women; the range on your report applies. SHBG rises with age in men and is higher in women, in pregnancy and on oral estrogen, and lower with obesity and insulin resistance.
What does high SHBG mean for a man?
More of his testosterone is bound and unavailable, so free testosterone can be low even when total testosterone reads normal. Common causes are aging, hyperthyroidism, liver disease, low body weight and certain medications. Calculated free testosterone — from total testosterone, SHBG and albumin — shows whether the free level is actually adequate.
What does low SHBG mean?
Low SHBG is most often a metabolic signal — insulin resistance, obesity, metabolic syndrome or type 2 diabetes suppress its production — and it is also seen in PCOS, hypothyroidism and with androgen or steroid use. In women it means more free androgen reaches tissues; in men it means free testosterone may be closer to normal than a low total suggests.
Should SHBG be tested with testosterone?
Yes, whenever total testosterone is borderline or a condition that alters SHBG is present (obesity, diabetes, older age, thyroid or liver disease, HIV, or medications such as oral estrogen or anticonvulsants). Guidelines recommend the pair, drawn in the morning from the same sample, so free testosterone can be calculated.
Does birth control affect SHBG?
Strongly. Oral combined contraceptives raise SHBG two- to three-fold by their effect on the liver, which lowers free testosterone — part of how they improve acne. Transdermal or vaginal estrogen has far less effect. Mention any hormonal contraception when SHBG or testosterone is being interpreted.
What does a high SHBG mean?
High SHBG binds more testosterone and estradiol, lowering the free, active fraction — so total hormone levels can look normal while free levels are low. Common causes are oral estrogens (including birth control pills), hyperthyroidism, liver disease, aging in men, low body weight, anorexia and some anticonvulsants. Free testosterone is the number to look at when SHBG is high.
My total testosterone is normal but I have low-T symptoms. Could SHBG explain it?
Yes — high SHBG lowers free testosterone. Ask for a calculated free testosterone using the measured SHBG.
What does a low SHBG mean?
Low SHBG is strongly associated with insulin resistance — excess weight, type 2 diabetes, fatty liver, PCOS — and with hypothyroidism, anabolic steroid or testosterone use, and glucocorticoids. It raises free testosterone relative to total, which contributes to acne and hair growth in women with PCOS. Low SHBG is also an independent marker of future type 2 diabetes risk.
Is low SHBG bad?
It's a metabolic warning sign more than a problem in itself — it tracks insulin resistance and predicts diabetes risk. Weight, activity and blood-sugar improvements raise it.
Do I need a doctor's order to test my shbg?
No. TestWell's licensed physician network reviews and approves your order — usually within minutes. You can place an order online without an in-person visit or a referral from your own doctor.
How long does it take to get SHBG results?
Most SHBG results are available in 1–3 business days after your specimen arrives at the lab. You'll get an email the moment your results are ready, with everything viewable in your TestWell portal.
How much does a SHBG test cost?
Our Testosterone, Free & Total + SHBG starts at $69.99. That's the all-in price — no copays, no insurance hoops, no surprise bills. HSA and FSA cards are accepted.
Do I need to fast before my SHBG test?
Fasting is not required for the SHBG test. You can have your blood drawn any time of day.
Which lab will process my SHBG test?
Your test will be processed by Quest Diagnostics, Labcorp, or BioReference depending on which is closest to you and which lab carries the test. All three are CLIA-certified and trusted by hospitals nationwide. You'll choose your lab during checkout from 4,000+ locations.
What can throw off a SHBG result?
Common medications and oral contraceptives and estrogen can change a SHBG result without anything being wrong. Common medications can raise SHBG — free testosterone and SHBG interpreted in that context. Oral contraceptives and estrogen can raise SHBG — expected; interpret testosterone with it. Each is explained on our physician-reviewed "Before your test" pages; when one applies, remove it and retest.
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