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Hormones
In the UK, the standard clinical (NHS) reference range for SHBG (Sex Hormone Binding Globulin) is 18.3-54.1 nmol/L (male), with 25-45 nmol/L considered the performance-optimised range. A result within these ranges suggests typical status; only a qualified clinician can interpret an individual reading.
SHBG is a glycoprotein produced primarily by the liver that binds to sex hormones — testosterone, dihydrotestosterone (DHT), and oestradiol — and regulates their bioavailability. Only the unbound (free) fraction of testosterone is biologically active, so SHBG levels directly determine how much testosterone your body can actually use. SHBG is influenced by thyroid function, insulin levels, liver health, and body composition.
Optimal range · UK
25-45 nmol/L
Performance-optimised band · clinical (NHS) range 18.3-54.1 nmol/L (male)
Reference ranges for SHBG, not a personal result. Any individual reading should be interpreted by a qualified clinician.
Optimal ranges
| Range | Value |
|---|---|
| Clinical (NHS) reference range | 18.3-54.1 nmol/L (male) |
| Performance-optimised range | 25-45 nmol/L |
The clinical range defines what is considered medically “normal” — broad enough to cover 95% of the population. The performance range reflects where research and clinical experience suggest most people feel and function at their best. A result in either range suggests typical status and is not a diagnosis; any individual reading should be interpreted by a qualified clinician.
Why it matters
A man can have a normal total testosterone level but still experience symptoms of low T if his SHBG is too high — because most of his testosterone is bound and unavailable. Conversely, very low SHBG can lead to excess free testosterone converting to oestrogen via aromatase, causing its own set of problems. SHBG is a critical piece of the hormonal puzzle that is often missed in standard blood tests. Elevated SHBG is associated with hypothyroidism, liver disease, and caloric restriction; low SHBG is linked to insulin resistance, obesity, and type 2 diabetes risk.
Symptoms
Low / Deficiency
High / Excess
Dietary sources
Supplementation
SHBG itself cannot be supplemented — the goal is to address the underlying cause of abnormal levels. For high SHBG: check thyroid function (hypothyroidism raises SHBG), ensure adequate caloric intake (undereating raises SHBG), and consider boron supplementation (6-10mg daily has been shown to reduce SHBG by ~10% in some studies). For low SHBG: improve insulin sensitivity through exercise and weight management, reduce refined carbohydrates, and address any fatty liver disease. Nettle root extract (Urtica dioica) is marketed as an SHBG modulator but clinical evidence is limited to in-vitro studies.
Testing
SHBG is measured from a blood sample. With Helvy, that means a finger-prick kit taken at home and posted to a UKAS-accredited UK laboratory, with results in around 5 days, reviewed by a qualified clinician. Your result is reported against both the clinical range (18.3-54.1 nmol/L (male)) and the performance-optimal range (25-45 nmol/L), so you can see not just whether you are “normal” but whether you are optimal. If you make a change, retest after 8-12 weeks to confirm it worked.
Research
Sex hormone-binding globulin and risk of type 2 diabetes in women and men
Ding EL, Song Y, Manson JE, et al.
New England Journal of Medicine (2009)
DOI: 10.1056/NEJMoa0804381Test for this
Related biomarkers
Related guides
Testosterone Blood Test UK
SHBG binds testosterone — levels matter
Women's Hormone Testing Hub
Every Helvy women's hormone guide in one place
Testosterone Blood Test for Women UK
SHBG drives the free androgen index
PCOS Blood Test UK
Low SHBG is a key PCOS marker
Hormone Imbalance Blood Test
Signs & what gets tested
This content is for educational purposes only and does not constitute medical advice. Your data suggests areas for optimisation, but any concerns should be discussed with a qualified healthcare professional. If your results flag values outside safe ranges, we recommend consulting your GP.
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