What it measures
SHBG (sex hormone binding globulin) is a protein made in the liver that carries testosterone and oestradiol in the blood. Hormone bound to SHBG is not available to the body's tissues, so the SHBG level affects how much testosterone is free.
Why people test it
- Measured with total testosterone to work out free testosterone, often when symptoms and total testosterone do not match.
- Checked in women with excess hair growth, acne or irregular periods, usually with testosterone.
- Thyroid, liver and weight changes all shift SHBG, so it is read alongside other results.
- Monitored on TRT, as SHBG decides how much of the total testosterone is free.
- Anabolic steroids can lower SHBG, which changes how a testosterone result reads.
Typical range
Ranges vary between labs, with the method used, age and sex, and your report shows the lab's own range. One NHS trust lab gives 17 to 78 nmol/L for adult men and 34 to 148 nmol/L for women aged 19 to 49. Source: Oxford University Hospitals NHS Foundation Trust: biochemistry reference ranges.
Finger-prick or vein?
A vein draw is usually advised. SHBG is usually tested with testosterone, and testosterone gels or creams on the fingers can contaminate a finger-prick sample.