Biomarker Glossary
SHBG
SHBG (sex hormone binding globulin) is a protein made by the liver that binds to testosterone and oestrogen and controls how much of each is biologically active in your body. SHBG is tested alongside total testosterone and oestradiol to assess free hormone levels, and changes with insulin resistance, thyroid function and liver health.
Also known as: Sex Hormone Binding Globulin, Sex Steroid Binding Protein
SHBG is most informative when read alongside related markers like Testosterone and Insulin. A single number rarely tells the whole story. If your reading sits outside the typical range, share the full report with your GP or healthcare professional before drawing conclusions.
What is SHBG?
SHBG binds tightly to testosterone, dihydrotestosterone (DHT) and oestradiol, keeping them inactive while they circulate in the blood. Only the unbound (free) fraction can enter cells and exert its effect.
If SHBG is high, more hormone is bound and inactive, so symptoms of low testosterone or oestrogen may appear even when total levels look normal. If SHBG is low, more hormone is free and active, which can drive symptoms of excess.
SHBG is also a useful marker of liver health, thyroid function and metabolic status. It rises with hyperthyroidism, oestrogen, and ageing, and falls with insulin resistance, obesity and androgen excess.
Why test SHBG?
- To interpret total testosterone or oestradiol results more accurately.
- If you have symptoms of low or high hormone activity despite a normal total testosterone or oestradiol.
- To investigate PCOS, where low SHBG drives free androgen excess.
- To screen for insulin resistance and metabolic syndrome (low SHBG is an early marker).
- To monitor thyroid medication, hormonal contraceptives or hormone replacement.
To interpret total testosterone or oestradiol results more accurately.
SHBG normal range (UK)
| Result | What it means |
|---|---|
| Men: 18 to 54 nmol/L | Normal |
| Women (premenopausal): 32 to 128 nmol/L | Normal |
| Women (postmenopausal): 27 to 128 nmol/L | Normal |
| Below the normal range | Often associated with insulin resistance, obesity, PCOS, hypothyroidism |
| Above the normal range | Often associated with hyperthyroidism, oestrogen therapy, liver disease, anorexia |
Ranges from UK Royal College of Pathologists. Ranges vary by laboratory and assay. Always interpret SHBG alongside total testosterone or oestradiol.
About these ranges. The ranges above are typical UK clinical lab ranges aligned to NHS and Royal College of Pathologists guidance. Your Chxhealth report will show the specific reference range used by our partner lab, Randox, for each marker. Lab ranges vary slightly between providers and assays. Always interpret your results in the context of the range printed on your own report.
What causes high SHBG?
- Hyperthyroidism
- Oestrogen therapy or oral contraceptive pill
- Pregnancy
- Liver disease (hepatitis, cirrhosis)
- Anorexia or significant weight loss
- Anti epileptic medications
- Ageing in men
What causes low SHBG?
- Insulin resistance and type 2 diabetes
- Obesity (particularly central obesity)
- Polycystic ovary syndrome (PCOS)
- Hypothyroidism
- Androgen excess in women
- Steroid use
- Acromegaly (excess growth hormone)
Symptoms of high SHBG
- Symptoms typically mirror low free testosterone in men: low libido, fatigue, low mood.
- In women: usually no symptoms directly, but can mean lower bioavailable oestrogen.
Symptoms of low SHBG
- In men: symptoms of testosterone excess in some cases (acne, irritability)
- In women: PCOS-like symptoms (acne, facial hair, irregular periods)
- Often accompanies central weight gain, insulin resistance and fatty liver
How is SHBG tested?
SHBG is measured from a blood sample. Fasting is not strictly required but improves comparability if testing alongside insulin or glucose.
For sex hormone interpretation, test in the morning at the same time as testosterone or oestradiol.
Chxhealth samples are analysed by Randox, a UK laboratory accredited by UKAS. Results return in 3 to 5 working days.
How to support healthy SHBG levels
- If SHBG is low: address insulin resistance with lower carbohydrate eating, strength training and weight loss. SHBG often rises 20 to 50 percent within 6 months of these changes.
- If SHBG is high: address underlying causes such as thyroid imbalance, oestrogen exposure, or extreme calorie restriction.
- Limit alcohol, which affects liver SHBG production.
- Prioritise sleep and stress management, both of which influence hormone binding proteins.
These are general lifestyle suggestions. Chxhealth is an information service. For personal medical advice, please speak to a healthcare professional.
Chxhealth panels that test SHBG
10 Chxhealth biomarker panels include SHBG. Each is analysed by Randox, a UK laboratory accredited by UKAS. Reports are delivered in 3 to 5 working days.
- Elite Biohacking
- Athletic Performance Panel
- Weight Loss Commencement
- Weight Loss Monitoring
- Advanced GP3
- Endocrinology
- Fertility Panel
- Hormonal Health
- Sports Performance
- Testosterone Monitoring
SHBG FAQs
Why is SHBG important?
SHBG decides how much of your testosterone and oestrogen is biologically active. A normal total testosterone with low SHBG may look fine on paper but actually mean very high free testosterone. Testing SHBG alongside helps interpret hormones accurately.
What does low SHBG mean?
Low SHBG is most commonly seen in insulin resistance, obesity, PCOS and hypothyroidism. It is one of the earliest markers of metabolic dysfunction in lean adults and worth investigating even without other symptoms.
Can I increase SHBG naturally?
Yes. Weight loss, strength training, lower carbohydrate eating and treating thyroid imbalance all raise SHBG over months. Coffee intake is also linked to higher SHBG.
Should I test SHBG with testosterone?
Yes, ideally. Testing total testosterone alone misses important information. Adding SHBG (and ideally free testosterone) gives a much clearer picture of your true hormonal status.
What is the free androgen index?
FAI is a calculation: (total testosterone divided by SHBG) multiplied by 100. It estimates the proportion of testosterone available to act on tissues. Particularly useful for diagnosing PCOS and androgen excess in women.
Often tested with SHBG
The biomarkers below are commonly investigated alongside SHBG because they reveal connected aspects of the same physiological picture:
- Testosterone: Free testosterone calculations rely on SHBG.
- Insulin: Low SHBG often coincides with high insulin and metabolic dysfunction.
- Oestradiol: SHBG binds both testosterone and oestradiol.
Choose the right test for your goal
If you are reading about SHBG because of a specific health goal, our buying guides walk you through which Chxhealth panels fit:
- Best blood test for testosterone (men 30+)
- Best blood test for women's hormones
- View all blood test guides
Sources and further reading
This page is informed by guidance from the NHS, NICE, Royal College of Pathologists and other UK authoritative bodies. For deeper detail or to verify the information, see:
- Society for Endocrinology: Sex hormone binding globulin
- NHS: Polycystic ovary syndrome
- Lab Tests Online UK: SHBG
About this page. Last reviewed: 13 May 2026. Next scheduled review: May 2027. This page has not yet been independently reviewed by a clinician. It is written from authoritative UK medical guidance (NHS, NICE, Royal College of Pathologists, peer-reviewed sources) but has not undergone formal clinical sign off.
Important. Chxhealth is a UK information service. We do not diagnose, treat or prescribe. The reference ranges and information on this page are general educational content and should not be used as a substitute for advice from a qualified healthcare professional. For any concerns about your health or results, please speak to your GP or another healthcare professional.