SHBG Test

What this test actually measures

SHBG is a carrier, and carriers get less attention than cargo even when they decide what the cargo can do.

Your liver makes it, it circulates, and it binds sex hormones, most tightly testosterone and to a lesser degree oestradiol. Hormone bound to SHBG cannot enter a cell and act.

So SHBG is effectively a regulator of availability. More SHBG means more of your hormone is held in reserve and less is free to work. Less SHBG means more is available.

Which produces the interpretive problem this test exists to solve. If your SHBG doubles, your total testosterone can look perfectly healthy while the amount reaching your tissues has halved. And if it drops, a modest total can be doing more work than the number suggests.

That is why a total hormone measurement is genuinely difficult to interpret without knowing what the carrier is doing.

What a high or low result is pointing at

SHBG is unusual among the markers here in that it is rarely the problem itself. It is a signpost, and what it points at is often more interesting than the number.

A low SHBG is most commonly associated with insulin resistance. Insulin suppresses SHBG production in the liver, so a low result frequently means insulin is running high, which is one of the reasons this marker turns up in polycystic ovary syndrome and in metabolic syndrome.

That is genuinely useful, because it means a low SHBG is a nudge to look at fasting insulin and HbA1c. You can also check your triglyceride to HDL ratio free from a lipid panel already in your records, and a 2024 systematic review of 32 studies covering 49,782 participants supported that ratio as a simple accessible marker of insulin resistance.

Excess visceral fat, a low-protein or high refined carbohydrate diet, and an underactive thyroid also lower it.

A high SHBG points somewhere different. An overactive thyroid raises it, oral oestrogen including many hormonal contraceptives raises it substantially, liver disease raises it, and it tends to rise with age. Under-eating and very low body fat raise it too.

That contraceptive effect is worth knowing about specifically, because it explains a common and confusing pattern: someone on an oral contraceptive with low libido whose total testosterone looks fine. The total is fine. The free fraction is not, because the carrier went up.

So the productive way to read this test is as a question rather than an answer. A result outside the range is telling you to look at insulin, thyroid, liver or medication, and any of those is more actionable than the SHBG number itself.

Test details

What is measured: sex hormone binding globulin, usually in nmol/L.

Sample: blood draw.

Provider: Quest Diagnostics, ordered through Jess's practitioner dispensary.

Fasting: not generally required. If drawn alongside testosterone, a morning draw applies to the order.

Turnaround: results typically within a few business days of the sample reaching the lab.

Order this test.

How the pricing works

I want to be straightforward about this, because lab pricing in the wellness industry frequently is not.

Jess takes no markup on the test itself. The lab cost is passed through exactly as it comes. What you pay is the test cost, the dispensary's service fee, the authorization fee, the collection fee where one applies, a flat handling fee for placing and managing the order, and the card processing cost. The handling fee is the part that is Jess's, and it is flat regardless of how expensive the test is.

That structure is deliberate. A percentage markup on labs creates an incentive to recommend expensive tests, and this way there is not one.

Because every blood test in one order shares a single draw fee, adding a second or third test to the same order costs considerably less than ordering them separately. The full lab menu shows what shares a draw with this one, and the order page itemises every fee before you pay.

Who this test is worth running for

Anyone testing testosterone. That is the primary case, because a total testosterone without an SHBG is a number whose meaning depends on something you did not measure.

Anyone with low libido or fatigue while on an oral contraceptive, since that combination specifically raises SHBG and lowers the free fraction.

Anyone working up polycystic ovary syndrome or a metabolic picture, where a low SHBG is a useful corroborating signal alongside fasting insulin, testosterone and DHEA sulfate.

Ordering restrictions

The lab network cannot issue orders to residents of New York, New Jersey, Rhode Island, or Hawaii. New York, New Jersey, and Rhode Island prohibit direct-to-consumer lab testing outright, requiring a treating provider's signature on every requisition. Hawaii is excluded by the network. This is tied to where you live, not where the sample is collected, so it applies to kits as well as draws.

If you live in one of those four states, your doctor can order the same test.

What to do with the result

If SHBG is low, look at insulin. That is the most common driver, and fasting insulin with HbA1c is the pairing that answers it. Improving insulin sensitivity generally raises SHBG back.

If SHBG is high, look at thyroid and medication. An overactive thyroid and oral oestrogen are the usual explanations, and both are checkable.

If SHBG is high and you have low libido on an oral contraceptive, that is a recognised pattern worth raising with your prescriber rather than working around.

Interpret your testosterone through it. A total in the lower half with a raised SHBG means something different from the same total with a normal SHBG.

Take it to someone who reads the set together. SHBG alone is a signpost, and the value is in what it points at.