What is sex hormone-binding globulin (SHBG)?
Sex hormone-binding globulin (SHBG) is a protein made by the liver that carries testosterone, dihydrotestosterone and estradiol in the blood. Hormones bound to SHBG are inactive, so SHBG levels affect how much free, active hormone your tissues see. Low SHBG means more free testosterone; high SHBG means less.
What changes SHBG
| Lowers SHBG | Raises SHBG |
|---|---|
| Insulin resistance and PCOS | Estrogen-containing pills |
| Higher body weight | Pregnancy |
| Underactive thyroid | Overactive thyroid |
| High androgens | Liver conditions, aging, very low weight |
Why it matters
In PCOS, high insulin lowers SHBG, so more testosterone is free. That can worsen acne, excess hair and irregular cycles even when total testosterone is only mildly raised. Doctors often measure SHBG alongside testosterone to calculate a free androgen index. Learn more in androgens and testosterone.
The combined pill raises SHBG, which is one reason it helps acne and hair growth. Very high SHBG on the pill has been linked in some people to lower libido, which may linger for a while after stopping.
Testing
SHBG is a simple blood test, usually done with testosterone when someone has irregular periods, acne, excess hair, or low libido. Results are read alongside symptoms and other hormones, not on their own.
SHBG isn't known to act on mood directly, but the androgen symptoms it influences, like acne and hair changes, can weigh on confidence and body image.
Frequently asked questions
What does low SHBG mean?
More testosterone is free and active. It's common with insulin resistance and PCOS.
Can I raise SHBG naturally?
Improving insulin sensitivity through activity and diet can raise it in some people. Talk to a doctor before trying supplements.
Does the pill affect SHBG?
Yes. Pills containing estrogen raise SHBG, often a lot, which lowers free testosterone. Levels usually drift back down over the months after stopping, though this varies from person to person.
Sources
This page is for information only and isn’t medical advice. If something worries you, please talk to a doctor.
Keep reading
What is PCOS (polycystic ovary syndrome)?PCOS (polycystic ovary syndrome) is a common hormone condition causing irregular periods, high androgens and ovulation problems. Signs, diagnosis and care.
Testosterone in women: definition and meaningTestosterone is not just a male hormone. What it does in women, how it shifts around ovulation, and what high or low levels can mean for mood and libido.
Androgens: definition and meaningAndrogens are hormones like testosterone and DHEA that everyone makes. What they do in women, how they link to PCOS, and signs your levels may be high.PCOS (now also called PMOS) and your cyclePCOS, now also called PMOS, explained: the common signs, how doctors diagnose it, what it does to your cycle and mood, and what helps day to day.
Menstrual cycle hormones: a simple chart of what rises and fallsMenstrual cycle hormones explained simply: how estrogen, progesterone, LH and FSH rise and fall through each phase, and how they shape mood and energy.