Total testosterone, free testosterone and SHBG test

Total testosterone, SHBG and albumin test, with calculated free testosterone and free androgen index. It is the first assessment when there are symptoms compatible with low testosterone or when you want to check a previous result. The sample must be taken in the morning, and a diagnosis of hypogonadism requires a low level to be confirmed on another day.

No prescription or appointment needed

Results in 1-2 working days

Includes: Total testosterone · SHBG · Albumin · Calculated free testosterone · Free androgen index. See what each one measures

What it is for

It is used for a first assessment when there is loss of sexual desire, fewer spontaneous erections, erection problems, reduced strength or a previous low testosterone result. Combining it with SHBG and albumin makes total testosterone easier to interpret, especially when SHBG may be altered by age, weight, the thyroid, the liver or some treatments.

This profile checks the hormone level, but it does not investigate the cause. If the result is confirmed as low and there are compatible symptoms, the next step is to measure FSH, LH, prolactin and thyroid function.

When it is recommended

Persistent loss of sexual desire or of spontaneous erections
Erectile dysfunction together with other symptoms of androgen deficiency
Loss of strength, muscle mass or body hair without a clear explanation
Checking a low or borderline testosterone result from a previous blood test
Situations in which SHBG may alter the interpretation of total testosterone

Clinical comment

Free testosterone measured by direct immunoassay is not accurate enough. Guidelines recommend measuring it by equilibrium dialysis or calculating it from total testosterone, SHBG and albumin. As equilibrium dialysis is not part of routine practice, we have designed this profile with the three tests needed for the calculation.

Bear in mind that calculated free testosterone is still an estimate and that the formulas do not produce identical results. The calculator on this website (in Spanish) shows the numerical value obtained from the figures in the report, but it does not interpret the result or replace a medical assessment.

Symptoms on their own are not enough for a diagnosis of hypogonadism either, because tiredness, low mood or erection problems have many causes. The diagnosis requires compatible symptoms and consistently low testosterone, confirmed in at least two morning samples taken on different days.

Dr. Antonio Mas

What is tested

Total testosterone: Measures all circulating testosterone, both the fraction bound to proteins and the free fraction.
SHBG: The main carrier protein for sex hormones. Changes in it can make total testosterone look normal even when the available fraction is different.
Albumin: Carries part of the testosterone and is used together with total testosterone and SHBG to estimate the free fraction.
Calculated free testosterone: Estimates the testosterone not bound to proteins using a validated formula. It is not measured by direct immunoassay.
Free androgen index (calculated): Relates total testosterone to SHBG. It adds a complementary figure, although in men calculated free testosterone is usually more useful.

These tests are used to calculate Testosterona libre calculada. They are not separate tests.

How to prepare

Have the sample taken in the morning, preferably before 10:00, after 8 hours of fasting. Avoid a very short night's sleep, intense exercise and acute illness, because they can temporarily lower testosterone.

You can add

Without another needle. It is offered when you order, so you do not have to decide now.

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Related blood tests

We have other profiles in Men with more or fewer tests:

The most comprehensive is not always the most useful. If you are not sure, the one we recommend to start with is Low testosterone assessment.

What it is based on

Endocrine Society · J Clin Endocrinol Metab 103(5):1715-1744
Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline
Advises against the direct immunoassay for free testosterone, because it is inaccurate, and recommends obtaining it by equilibrium dialysis or calculating it from total testosterone, SHBG and albumin. It also sets the harmonised total testosterone range at 264 to 916 ng/dL and asks for a fasting morning sample, repeated on two different days.

Protocol designed by Dr. Antonio Mas, specialist in Endocrinology and Nutrition, Spanish medical licence no. 080846289, and reviewed in September 2026.

This blood test is a standardised protocol and does not replace a medical consultation. If you have symptoms, a known condition or a complex clinical situation, speak to your doctor.