Insight into your SHBGlevel.
SHBG is the transport protein that binds sex hormones in your blood. The level of SHBG helps determine how much testosterone remains freely available, with personal explanation from our doctors.
Also known as: sex hormone binding globulin, sex steroid binding globulin
Interpreted by BIG-registered doctors
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Background
What is SHBG?
SHBG stands for sex hormone binding globulin. It is a transport protein, produced mainly in the liver, that binds sex hormones such as testosterone and oestradiol in the blood. Hormone bound to SHBG cannot bind directly to the receptors in your tissues. The level of SHBG therefore helps determine how much testosterone remains freely available.
This makes SHBG particularly useful alongside a testosterone measurement. With a high SHBG, total testosterone can appear normal while less is available, and with a low SHBG the opposite can apply. SHBG is influenced by thyroid function, liver function, insulin sensitivity, and oestrogens, for example when using the contraceptive pill.
In brief
Transport protein
Binds testosterone and oestradiol
Sets availability
Drives the free testosterone fraction
Made in the liver
Liver function affects the level
Context-sensitive
Thyroid, insulin, and oestrogens
Common reasons to test
When can insight into your SHBG be valuable?
Below are some situations in which measuring SHBG can provide insight.
Alongside testosterone
SHBG is most informative in combination with total and free testosterone. Together they show how much hormone is available.
With symptoms but a normal testosterone
When total testosterone falls within the reference range but questions remain, SHBG can add nuance to that picture.
With questions about metabolism
Reduced insulin sensitivity often goes together with a lower SHBG. The value is therefore sometimes viewed in a metabolic context.
With a known thyroid or liver condition
Both thyroid function and liver function influence the production of SHBG. A measurement gives insight into that effect.
When using oestrogens
Oestrogens, for example in the contraceptive pill or in hormone therapy, generally raise SHBG. Please mention this use during your intake.
For follow-up of a previous measurement
Those who previously had an abnormal SHBG can repeat the measurement to track the value over time.
What your result means
How do we read your SHBG level?
SHBG is measured in nanomoles per litre (nmol/L). The laboratory provides the reference ranges and takes sex and age into account. On its own, SHBG says little, the value gains meaning in combination with testosterone. A single measurement is not a diagnosis, our doctor places the result in your context.
A low value
A low SHBG means less testosterone is bound, so a relatively larger proportion remains freely available. A low value is seen with excess weight, reduced insulin sensitivity, an underactive thyroid, and with the use of certain hormones. In women, a low SHBG occurs with polycystic ovary syndrome (PCOS). Our doctor considers the value together with your testosterone and your context.
A normal value
An SHBG within the laboratory reference range means the binding of sex hormones is not clearly shifted. Your total testosterone then usually gives a representative picture of the available amount. If symptoms persist, our doctor will also consider other explanations.
An elevated value
A high SHBG binds more testosterone, so less remains freely available, even when total testosterone appears normal. An elevated value is seen with an overactive thyroid, with liver conditions, with the use of oestrogens such as the pill, and with increasing age. Free testosterone can then provide additional information.
How we interpret your result
Our doctors assess your SHBG against the laboratory reference ranges and your personal context, such as age, sex, medication use, and any known conditions. You receive a report in plain language, as a starting point for your own insight or a conversation with your healthcare provider.
Related tests
Often combined with SHBG.
A single marker gives one perspective. For a broader picture you can combine SHBG with a theme package or related markers.
Frequently asked questions
Everything you want to know
Do I need to fast for an SHBG test?
No, you do not need to fast for an SHBG measurement. If you measure SHBG together with testosterone, we recommend having your blood drawn in the morning, as testosterone follows a daily rhythm.
What is the difference between SHBG and testosterone?
Testosterone is the hormone itself. SHBG is the protein that binds and transports testosterone in the blood. SHBG therefore determines how much testosterone remains freely available to your tissues. The two values are best assessed together.
Why would I have SHBG measured?
An abnormal SHBG can distort your total testosterone value. With a high SHBG, the total can appear normal while less is available. SHBG helps our doctor to interpret your testosterone result correctly.
Which factors influence my SHBG level?
Thyroid function, liver function, insulin sensitivity, body weight, age, and oestrogens all play a role. Medication can also affect the value, so please mention your medication use during the intake.
Does the contraceptive pill affect my SHBG?
Yes. Oestrogens generally raise SHBG, and the pill often contains oestrogen. This effect can persist for as long as you take the pill. Our doctor takes this into account when interpreting your result.
Does the point in the cycle matter for women?
SHBG fluctuates far less across the cycle than hormones such as LH, FSH, oestradiol, and progesterone, so the point in the cycle is less decisive for SHBG. If you are measuring other hormones at the same time, do let us know where you are in your cycle.
How often should I measure SHBG?
A single measurement is sufficient for initial insight. With a previously abnormal value, or after a specific lifestyle or medication change, re-testing after a few months is common.
What do I do with my result?
You will receive a PDF report with your value and an explanation from our doctor. What you do with it, such as discussing it with your GP or arranging further testing, remains entirely your choice.
Ready for insight into your SHBG level?
For €79 you receive your SHBG level including personal explanation from a doctor, typically within a few working days. No referral required.
Order SHBG for €69 →Want to test multiple markers at once?
Combine SHBG with other markers via Bloodworks Select. Blood draw costs are waived from €225.
69,-
All-in, blood draw included