Sex Hormone Binding Globulin (SHBG)
SHBG is a protein that binds and carries sex hormones in the blood. Low SHBG increases free testosterone and is associated with PCOS, insulin resistance, and metabolic syndrome.
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What the Sex Hormone Binding Globulin (SHBG) test tells you
Sex hormone binding globulin, usually shortened to SHBG, is a carrier protein made by the liver. Most of the testosterone and oestradiol circulating in the blood is not floating free: it is held by SHBG, which binds it tightly, and by albumin, which holds it loosely. Only the small unbound portion, together with the part loosely attached to albumin, can readily leave the bloodstream and act on tissues. SHBG therefore does not produce any hormone of its own; what it does is decide how much of the hormone already present is actually available to be used.
That role is why SHBG is measured. Two people can have an identical total testosterone and yet be in quite different situations, because one has a high SHBG holding most of it out of circulation and the other has a low SHBG leaving more of it active. This is the single most common reason a total testosterone result and a person's symptoms fail to agree, and it is why SHBG is requested alongside testosterone rather than on its own. From the two together, a free testosterone can be calculated and the picture usually resolves.
SHBG also carries information in its own right, because the things that move it are informative. It falls with excess body weight, insulin resistance, an underactive thyroid, and exposure to androgens or anabolic steroids, so a low SHBG often appears in metabolic syndrome and in polycystic ovary syndrome, where the low level raises the active fraction of testosterone and contributes to the symptoms. It rises with an overactive thyroid, with oral oestrogen including some contraceptives, in pregnancy, with liver disease and with age. Read this way it becomes a useful cross-check on whether a hormone result makes sense in the context of the rest of the person.
Essential for interpreting testosterone results, evaluating PCOS in women, assessing hypogonadism in men, and understanding metabolic syndrome risk.
- Making sense of testosterone
SHBG is the reason a total testosterone can look normal while symptoms persist, so measuring the two together often explains an apparent contradiction.
- Calculating free testosterone
The unbound, active fraction is usually derived from total testosterone together with SHBG and albumin rather than measured directly.
- Assessing androgen excess in women
A low SHBG raises the proportion of testosterone that is active, which is a common contributor to symptoms in polycystic ovary syndrome.
- A window on metabolic health
SHBG falls with insulin resistance and excess weight, so a low result can prompt a wider look at metabolic risk.
Reasons your doctor may request the Sex Hormone Binding Globulin (SHBG) test
Your doctor may order this test for any of the reasons below. Some are routine checks, others follow specific symptoms or an earlier result.
Low testosterone, excess hair & acne
- Investigating symptoms of low testosterone in a man, particularly where the total result is borderline.
- Assessment of polycystic ovary syndrome, excess hair growth or acne in a woman.
When hormone results do not fit
- Any situation where SHBG is expected to be unusual: obesity, thyroid disease, liver disease or oestrogen therapy.
- Investigating persistent symptoms when previous hormone results have not fitted the clinical picture.
Free testosterone & replacement therapy
- Calculating free testosterone as part of a fuller androgen assessment.
- Monitoring during testosterone replacement, where SHBG shapes how much of the dose is active.
SHBG is a carrier protein, so it decides how much of your sex hormone is free to act rather than how much exists. A result in the Normal band, 18 to 54 nmol/L, needs no action of its own. A Low result, 0 to 17 nmol/L, is most often linked to excess body weight and insulin resistance, and is a frequent finding in diabetes, metabolic syndrome and polycystic ovary syndrome, where it raises the active fraction of testosterone. A High result, 55 to 200 nmol/L, fits an overactive thyroid, oral oestrogen or pregnancy, liver disease, very low body weight, and rising age in men. Because SHBG is usually the explanation when total and free testosterone tell different stories, it is read as part of a hormone assessment rather than alone. Thyroid status, oestrogen therapy and liver disease need to be known first. Your doctor reads it with your testosterone, albumin, symptoms and history.
Medically reviewed by Dr Nirupama Sabhapathy
Ranges are a guide: your physician interprets your result alongside your symptoms and history.
What a higher result can point to
- An overactive thyroid, which raises SHBG production by the liver.
- Oral oestrogen, including some combined contraceptives and menopausal hormone therapy, and the raised oestrogen of pregnancy.
- Liver disease, particularly cirrhosis, which alters how the liver makes and handles carrier proteins.
- Very low body weight, disordered eating or prolonged undernutrition.
- Increasing age in men, which is one reason total testosterone can hold up while the active fraction falls.
- Some medications, including certain anticonvulsants.
What a lower result can point to
- Excess body weight and insulin resistance, the commonest reasons for a low SHBG.
- Type 2 diabetes and metabolic syndrome, in which a low SHBG is a frequent accompanying finding.
- Polycystic ovary syndrome, where the low level increases the active fraction of testosterone.
- An underactive thyroid, which reduces liver production of the protein.
- Testosterone therapy, anabolic steroid use or other androgen exposure.
- Glucocorticoid treatment, and conditions in which protein is lost through the kidneys.
These are possibilities, not diagnoses. A single value outside the reference range is interpreted alongside your symptoms, history and other tests: your doctor decides what it means for you.
What this test cannot tell you
- SHBG is not a diagnosis on its own; it is interpreted as part of a testosterone or oestrogen assessment and has little meaning in isolation.
- Calculated free testosterone depends on assumptions built into the formula and on the albumin value used, so results from different calculations are not interchangeable.
- Oestrogen therapy, thyroid disease and liver disease all move SHBG substantially, and these need to be known before the result can be judged.
- A single measurement reflects current metabolic and hormonal conditions, which can change as weight, thyroid status or medication changes.
Risks of the blood draw
- Mild bruising or brief soreness where the needle went in.
- Occasional lightheadedness, which settles after a few minutes of rest.
- Bleeding or infection at the site, which is rare with sterile single-use equipment.
- 1SHBG is a carrier protein, not a hormone; it decides how much of your sex hormone is available rather than how much exists.
- 2It is the usual explanation when total testosterone and free testosterone tell different stories.
- 3A low SHBG is closely linked to excess weight and insulin resistance; a high one to thyroid overactivity, oestrogen and liver disease.
- 4Free testosterone is normally calculated from total testosterone, SHBG and albumin together.
- 5It should be requested alongside a testosterone measurement, not on its own.
Sex Hormone Binding Globulin (SHBG) also comes in these focused packages, which pair it with the tests usually read alongside it.
- Hormones & FertilityTestosterone, Total
Total testosterone measures all testosterone in your blood: free, albumin-bound, and SHBG-bound. It is the primary test for evaluating male…
65View - Hormones & FertilityTestosterone, Free
Free testosterone measures the biologically active form not bound to proteins. It is a more accurate indicator of androgen status than total…
90View - Hormones & FertilityEstradiol (E2)
Estradiol is the primary female sex hormone responsible for reproductive development and menstrual cycle regulation. Testing helps evaluate…
55View - Hormones & FertilityLuteinizing Hormone (LH)
LH is a pituitary hormone that triggers ovulation in women and stimulates testosterone production in men. Abnormal levels help diagnose fertility…
60View
Frequently Asked Questions
Everything you need to know about the Sex Hormone Binding Globulin (SHBG) test. Can't find what you're looking for?
Talk to our team→Our laboratory reports 18 to 54 nmol/L as normal for adults. A result of 0 to 17 nmol/L is reported as low and may relate to insulin resistance or androgen excess, and 55 to 200 nmol/L is reported as high and needs clinical context. SHBG has little meaning alone, so your doctor reads it with your testosterone and albumin.
The common causes are an overactive thyroid, oral oestrogen from some combined contraceptives or menopausal hormone therapy, the raised oestrogen of pregnancy, and liver disease, particularly cirrhosis. Very low body weight, disordered eating or prolonged undernutrition can also raise it, as can increasing age in men and certain anticonvulsants. Thyroid status and medicines are checked first.
A low SHBG is a frequent finding in polycystic ovary syndrome. With less carrier protein, more testosterone is free to act, which can strengthen androgen effects even when total testosterone looks only modestly raised. A low SHBG also tracks with insulin resistance, which often accompanies the condition. Your doctor reads it with your testosterone, symptoms and other hormone results.
It can. A low SHBG is most often linked to excess body weight and insulin resistance, and a single result reflects your current metabolic state, so it can change as weight and insulin sensitivity change. That is one reason your doctor may repeat SHBG and testosterone after a period of lifestyle change rather than relying on one earlier figure.
Yes. When SHBG is high, more testosterone is bound and less is free to act, so total testosterone can look normal while the active fraction is low. This becomes more common with age in men and with an overactive thyroid or liver disease. Calculating free testosterone from total testosterone, SHBG and albumin helps your doctor assess possible low testosterone.
Because the carrier decides how much of the hormone can act. Two people with the same total testosterone can differ considerably in how much is available to their tissues, depending entirely on their SHBG. Measuring it turns an ambiguous total result into an interpretable one.
The most frequent explanations are excess body weight and insulin resistance, which both reduce how much of the protein the liver makes. An underactive thyroid and any androgen exposure, including testosterone therapy, do the same. Your doctor will look at the result in the context of your weight, thyroid tests and medications.
Yes, noticeably. Oestrogen taken by mouth increases SHBG production by the liver, which raises the total testosterone while lowering the fraction that is active. This is worth knowing before testosterone results from someone using combined contraception are interpreted.
In most laboratories it is calculated from total testosterone, SHBG and albumin. The calculation is reliable enough for everyday use but rests on assumptions, so an unexpected result may prompt your doctor to repeat the tests or request a directly measured free testosterone.
Not for SHBG itself. It is almost always requested with testosterone, which is conventionally sampled in the morning, so plan a morning appointment and follow any fasting instruction for the other tests booked at the same time.
The SHBG test is AED 70, including a physician-reviewed report, with results usually within 24 hours. Home collection anywhere in Dubai is free when your order reaches AED 300 or includes a package; below that, a AED 100 home collection fee applies (AED 50 for a lab walk-in).