Quick answer: SHBG (sex hormone-binding globulin) is a protein made by the liver that binds testosterone and estrogen, controlling how much is free and active. Low SHBG, often linked with insulin resistance and excess weight, raises free hormones and is common in PCOS. High SHBG lowers free testosterone and can occur with aging, hyperthyroidism, low-calorie diets or estrogen therapy.
What is SHBG?
SHBG is a liver protein that carries sex hormones in the blood. Hormones bound to SHBG are inactive; only the free portion acts on tissues. This marker is part of the Healthspan Assessment panel available to my 1-on-1 patients.
Why SHBG matters
- Controls free testosterone and estrogen
- Helps interpret total testosterone
- Reflects insulin and liver health
Understanding your result
Reference ranges vary by lab, age and sex. Your provider interprets your result against the lab’s range and your overall picture, rather than chasing a single number. Functional labs are optional. They can be helpful in more complex cases, and in my practice they are available only to patients working 1-on-1 with me.
What low SHBG can mean
- Insulin resistance and type 2 diabetes
- Excess weight
- PCOS
- Hypothyroidism
- Androgen or steroid use
What high SHBG can mean
- Aging (especially in men)
- Hyperthyroidism
- Estrogen therapy or birth control
- Liver disease
- Very low-calorie or low-protein diets
What affects SHBG
- Insulin levels
- Thyroid function
- Body weight
- Estrogen exposure
- Liver health
Ways to support healthy levels
- Improve insulin sensitivity to raise low SHBG (see insulin sensitivity)
- Check thyroid function
- Eat enough protein and calories
- Interpret with total and free testosterone
SHBG and healthy aging
SHBG reflects metabolic health: low levels track with insulin resistance and inflammation, while high levels in older men can reduce active testosterone, affecting muscle and energy.
When to see a naturopathic doctor
- Symptoms of low testosterone with normal total testosterone
- Signs of PCOS
- Insulin resistance
- Thyroid concerns
Want help making sense of your labs?
A free 15-minute consultation with Dr. Kneessi. No cost, no obligation. In-office in Odenton, MD or by telehealth.
Frequently asked questions
What does low SHBG mean?
It often reflects insulin resistance and is common in PCOS.
What does high SHBG mean?
It lowers free testosterone and can occur with aging, hyperthyroidism or estrogen use.
How can I raise SHBG naturally?
Improving insulin sensitivity and losing excess weight often raises SHBG.
Why test SHBG with testosterone?
It helps estimate how much testosterone is actually free and active.
Sources
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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