Androgens . Patient guide
Sex Hormone Binding Globulin (SHBG)
What is SHBG
SHBG is the carrier protein that binds testosterone and oestradiol in the bloodstream and controls how much is biologically available to tissues. SHBG is essential for calculating the free testosterone fraction from a total testosterone result.
This biomarker entry is being clinically reviewed by our team. The factual content draws on UK guidance (NICE, NHS, Royal Colleges and the relevant speciality society where cited).
Reference range
Reported in nmol/L. Final reports always carry the issuing laboratory's range, which is what your clinician will interpret against.
| Group | Range | Note |
|---|---|---|
| Adult men | 18 to 54 | nmol/L |
| Cycling women | 32 to 128 | |
| Postmenopausal women | 27 to 128 |
What it is
SHBG is made by the liver and binds tightly to testosterone and oestradiol, sequestering them from receptor binding until released. Only the free fraction (around 1 to 2 percent of total) is biologically active. SHBG is therefore not a hormone in its own right but the regulator that turns a total testosterone reading into a clinically meaningful free testosterone reading.
Why a clinician would order it
SHBG is requested whenever total testosterone is measured (to calculate free testosterone), in the work-up of androgen excess in women (low SHBG raises free testosterone effect for any given total), in metabolic risk assessment (low SHBG is an independent marker of insulin resistance), and in suspected hyperthyroidism or hypothyroidism (thyroid status shifts SHBG up or down respectively).
If your level is outside the range
Symptoms of low SHBG
- Symptoms typically reflect raised free androgen effect: acne, hirsutism, scalp hair thinning (women), oily skin
- Often clustered with insulin resistance: central weight gain, afternoon energy slumps
What low can indicate. Insulin resistance (the commonest non-androgen cause), PCOS, obesity, hypothyroidism, exogenous androgen use (TRT, anabolic steroids), Cushing's syndrome.
Symptoms of high SHBG
- Symptoms typically reflect reduced free androgen effect: low libido, fatigue, reduced muscle mass (men particularly)
What high can indicate. Hyperthyroidism, oral oestrogen (oral contraceptive or HRT), pregnancy, liver disease (cirrhosis), anorexia or significant weight loss, ageing (SHBG rises with age in men).
Testing tips
No fasting required. Hold oral oestrogen-containing contraceptives or HRT for at least 6 weeks if a true baseline is needed (they sharply raise SHBG). Always interpret alongside total testosterone so the calculated free testosterone can be derived: most labs report this automatically. SHBG also moves with thyroid status, so abnormal results merit a TSH check.
Where you can get this tested
Sex Hormone Binding Globulin is included in the following WMG Health panels. Same-day appointments at our Harley Street clinic, with results clinician-reviewed.
Want a specific combination of markers we do not have a panel for? Build a custom panel and our clinicians will design one for you.
Sources
UK guidance our clinicians use when interpreting this marker.
This page is general patient information, not personal medical advice. A GMC-registered clinician will review your results and tailor any interpretation to you. See our Editorial Policy for how we write and review content.