Hormone transport
Low SHBG Levels UK: What a Result Under the Range Means
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed October 20265 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
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NHS labs put the male floor somewhere between 13 and 15 nmol/L, and the female floor between 18 and 30. SHBG is the protein that holds testosterone in reserve. A low result means more of your testosterone is free, so the total reads better than it is.
Not sure which markers you need? Build your test →Your SHBG came back at 11 and the report flagged it low. Your testosterone looked fine. Nobody explained how those two facts fit together, and most of what you can find online is about the opposite problem.
Start with what the protein does. SHBG stands for sex hormone binding globulin. Your liver makes it, and it grips testosterone and oestradiol tightly and carries them around in an inactive form. Think of it as the bank rather than the cash.
1. What counts as a low SHBG in the UK?
Your own lab decides, and UK labs disagree more about SHBG than about almost any other hormone marker. Below are three NHS ranges for adults, in nanomoles per litre.
| Lab | Men | Women |
|---|---|---|
| Severn Pathology | 13 to 90 | 18 to 136 (18 to 46 years) |
| Gloucestershire Hospitals | 15 to 64 (under 50) | 19 to 145 (under 50) |
| North West London Pathology | 15 to 55 | 30 to 100 |
Look at the women's column. North West London starts flagging under 30. Severn Pathology starts at 18. A woman at 22 is low at one and normal at the other. So the only range that matters is the one printed on your report.
Age shifts it too. Our SHBG levels by age chart shows the full band for each decade rather than just the floor.
2. Why does SHBG come back low?
One NHS lab lists the causes in a single sentence, and it is the most useful sentence on the whole topic.
“Decreased SHBG levels can be seen in obesity, hyperinsulinaemia, hypothyroidism and growth hormone excess, as well as with glucocorticoids, androgens, progestins.”
Gloucestershire Hospitals NHS Foundation Trust pathology
In plain words, that list reads: carrying extra weight, high insulin, an underactive thyroid, and a handful of medicines. Hyperinsulinaemia means a lot of insulin in the blood. Glucocorticoids are steroids such as prednisolone.
Androgens belong on that list too, and they catch people out. Taking testosterone lowers SHBG. So does an anabolic steroid. If you are on either, a low SHBG is the expected result rather than a finding.
An underactive thyroid is the one most often missed, and it is easy to check. Our guide to normal thyroid levels covers what TSH and free T4 look like when the thyroid is running slow.
3. Does a low SHBG mean insulin resistance?
It raises the question. It does not answer it, and a lot of pages online skip that distinction.
Here is what the research shows. A review in Trends in Endocrinology and Metabolism reports that teenagers with metabolic syndrome ran an SHBG of about 21 nmol/L against 34 in controls. The same review says studies have implicated insulin as a suppressor of SHBG production in the liver.
Read the next line of that review as well. Its authors call the mechanism controversial, and point to blood sugar itself rather than insulin as the thing that may set SHBG. A marker that travels with a problem is not the same as a marker that measures it.
So if the insulin question is what is bothering you, measure the thing itself. HbA1c is your average blood sugar over about three months, and it is the marker a GP actually uses. It sits in our Advanced Heart Health panel.
Worth saying plainly. A blood test measures markers and gives you something concrete to take to a GP. It does not diagnose any condition, and one marker outside its range does not on its own mean something is medically wrong.
4. What does a low SHBG do to your testosterone result?
It flatters it. Total testosterone counts everything in the sample, bound and free. With less SHBG holding it, a bigger share of your total is active, so a mediocre total can behave like a better one.
That is the mirror image of the problem our guide to high SHBG with normal testosterone describes, where a healthy-looking total hides a thin free fraction. Same protein, opposite direction.
North West London Pathology puts the clinical side of it in one line: low concentrations in women may correspond with higher free testosterone concentrations leading to virilisation. That is the reason SHBG gets measured alongside total testosterone in women at all.
Two calculated figures do this arithmetic for you. The free androgen index divides testosterone by SHBG. Free testosterone estimates the active fraction directly. Neither means much without the SHBG that produced it, which is why a testosterone result on its own is hard to read.
5. Which blood test includes SHBG?
Two Helvy panels measure it. Complete Male Hormones reads SHBG with testosterone, free testosterone, LH, FSH, prolactin, DHEA-S, albumin and the free androgen index. Hormone Balance reads it with FSH, LH, total testosterone and the free androgen index.
The set is the reason to use either. SHBG on its own tells you very little. Read next to a total testosterone and the pituitary hormones above it, a low figure starts to mean something. Both are home finger-prick kits, processed by a UKAS-accredited UK lab.
Timing matters. Testosterone peaks in the early morning and falls through the day, so an afternoon sample reads lower for reasons that have nothing to do with you. Take the sample in the morning.
If you are not sure which fits, the build-my-test tool walks you through it in about a minute. The men's hormones hub collects the rest of these guides.
READY TO TEST?
See your SHBG next to the hormones it carries
Helvy's Complete Male Hormones test reports SHBG with testosterone, free testosterone, LH, FSH and prolactin, so a flagged number never sits there unexplained. Ask your blood.
Frequently asked questions
What SHBG level is considered low in the UK?
It depends on your lab. Severn Pathology starts flagging men under 13 nmol/L and Gloucestershire under 15. For women the floor runs from 18 at Severn to 30 at North West London Pathology. Use the range on your own report.
Is an SHBG of 15 nmol/L low?
For a man it sits at or just above most NHS floors. For a woman it is under every range listed here. The same number is two different results, which is why SHBG is always read against your sex and your lab.
What causes low SHBG?
Gloucestershire Hospitals pathology lists obesity, hyperinsulinaemia, hypothyroidism and growth hormone excess, along with glucocorticoids, androgens and progestins. Taking testosterone lowers it, which is the cause people most often forget.
Does low SHBG mean high testosterone?
Not high, but more available. Less SHBG means a bigger share of your total testosterone is free rather than bound. A total in the middle of the range behaves like a stronger result than the figure suggests.
How do I raise a low SHBG?
SHBG is not something to treat on its own. The NHS list points at the things underneath it instead, including weight, insulin and thyroid function. Take a low reading to a qualified clinician rather than chasing the number.
Which Helvy test measures SHBG?
Complete Male Hormones and Hormone Balance. The first reads SHBG with testosterone, free testosterone, LH, FSH, prolactin, DHEA-S and albumin. The second reads it with FSH, LH and total testosterone. Both are morning finger-prick samples.
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