How is testosterone measured: procedure, time of day, levels

What to expect in this article

1. What testosterone controls in the body
2. How the measurement is actually carried out
3. Why the time of day shifts the value
4. Total and free testosterone: what the difference means
5. What can shift a single value
6. How to interpret your report
7. Where you can have your levels measured
8. Which approach fits which question
9. What a testosterone level does not tell you
10. What ultimately matters
Frequently asked questions
Sources

What testosterone controls in the body

Testosterone is a sex hormone and belongs to the steroid group. It is produced primarily in the testes; to a lesser extent, the adrenal cortex also produces it (IQWiG, 2025).

According to the same source, its functions include ensuring that the sex organs develop and function properly. The hormone influences sperm production and is responsible for sexual desire (IQWiG, 2025).

Women also produce testosterone, in significantly smaller amounts. This explains why the reference ranges in the report are listed separately by sex and why a value without this classification cannot be interpreted.

What age does to testosterone levels

Testosterone levels do not remain constant throughout life. They reach their highest level in young adulthood and then gradually decline. This is not a disease, but a pattern over time.

For the measurement, this leads to a point that is often overlooked: According to IQWiG, the reference ranges also depend on age (2025). A report that gives a single range for all adults is less precise than one with age-specific ranges.

In practical terms, this means for interpretation: Compare your value with the range shown on your report, not with a number from a forum where the writer’s age is unknown.

How the control from above works

Production does not happen independently; it is directed by signals. The pituitary gland releases two regulatory hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

This is why LH and FSH are often measured together with testosterone. They show at which level a low result originates: in production itself or in the signal that triggers it.

How the measurement actually works

The procedure itself is unremarkable. What matters is the circumstances under which the sample is obtained.

The phrase “as a rule” is important. There is a second option: collecting capillary blood from the fingertip, as is customary for at-home tests. The sample volume is smaller, but the laboratory measures the same value.

What happens between the blood draw and the test report

The sample is sent to a laboratory, where it is analyzed using an immunoassay or mass spectrometry. The method used is stated on the report, and it affects the reference range.

This leads to a practical rule: Two results from two different laboratories are not readily comparable. Anyone who wants to monitor a trend should stick with the same laboratory and the same method.

How to prepare for the blood draw

Preparation consists of just a few steps, and none of them is complicated. The most important is the appointment itself: preferably in the morning, between 8 and 10 a.m. (IQWiG, 2025).

The second point is your list of medications. IQWiG explicitly identifies medications as a factor influencing testosterone levels (2025). This also includes products you buy without a prescription.

The third point concerns the evening before. Alcohol consumption and physical work are also on the list of influencing factors (IQWiG, 2025). An intensive workout the night before should therefore be noted on the test report, not forgotten.

And the fourth point: Write down the date and time as soon as the sample is taken. Six weeks later, no one will remember whether it was 8:30 or 3:30.

When women should be tested

For women, the menstrual cycle adds a second timing factor. IQWiG specifies a concrete time: Since the level in women is also influenced by the cycle, blood should be drawn, if possible, three to five days after the onset of menstruation (2025).

Without this information, a woman’s test result is difficult to interpret. The day of the menstrual cycle should therefore be included on the report, not left to memory.

Why the time of day shifts the result

Testosterone follows a daily pattern. The Institute for Quality and Efficiency in Health Care (IQWiG) derives a guideline for blood sampling from this: “It is important that this takes place between 8 and 10 a.m. Because testosterone levels change significantly throughout the day” (2025).

The time window is therefore not an organizational detail but part of the measurement. A sample taken at four p.m. does not measure the same person less accurately, but a different point on the same curve.

For you, this means: note the time. Without it, neither an individual value can be interpreted nor a second one compared with the first.

What this means for comparing two measurements

Many people measure a second time because they want to know whether anything has changed. The comparison is valid only under one condition: both samples come from the same time window.

If the first sample is taken at half past eight and the second at four p.m., the comparison primarily measures the difference between morning and afternoon. A change that actually occurred gets lost in the process.

The same logic applies to the laboratory. Because reference ranges depend on the laboratory and method (IQWiG, 2025), two values from two facilities are comparable only to a limited extent. Anyone who wants to monitor a trend should stick with one provider.

The objection is justified: this sounds like a lot of effort for one number. Even so, something else is decisive. The effort is only required the first time, because the pattern is then established—same time, same laboratory, recorded circumstances.

Checked against the evidence

Total and free testosterone: what the difference means

Some test results list only one testosterone value, while others list two. The difference is that the hormone does not circulate freely in the blood but is mostly bound to transport proteins.

The two most important transport proteins are SHBG, the sex hormone-binding globulin, and albumin. What is bound to SHBG is practically unavailable to the body.

Total testosterone measures both together: bound and unbound. Free testosterone describes the small fraction that can actually have an effect and, in many test results, is not measured directly but calculated from total testosterone, SHBG, and albumin.

The difference becomes practically important when the two values diverge. Normal total testosterone with high SHBG can be accompanied by a low free fraction—the result then looks less abnormal than it actually is.

Why SHBG appears as a separate value

SHBG stands for sex hormone-binding globulin. It is a protein that circulates in the blood and binds sex hormones, including testosterone.

The amount of this protein is not the same in everyone, and it changes over the course of life. That is exactly why SHBG appears as a separate line on many reports: without this value, free testosterone cannot be calculated.

One way to picture it: Total testosterone describes how many letters are in transit altogether. SHBG describes how many of them are inside a sealed envelope. Only the remainder gets delivered.

In practice, this means that if your report shows only one testosterone value and your symptoms persist despite an unremarkable result, asking about SHBG is the obvious next step.

Where the evidence becomes thin

The IQWiG page cited in the references does not address the distinction between total and free testosterone. It describes the blood draw, the time of day, and the reference ranges, not the division into bound and unbound portions.

That is why this section does not include a percentage indicating how large the free portion is. An estimated figure would be the greater error here. What appears on your report is the reliable figure.

What can shift a single value

In addition to the time of day and the menstrual cycle, IQWiG lists other factors affecting testosterone levels: stress, physical work, alcohol consumption, diet, and medication (2025). Age is another factor that influences the reference ranges.

This list is why a single measurement rarely leads to a decision. A value obtained after a sleepless night and a hard day of training reflects precisely those circumstances.

The individual factors

With stress, it is less about a demanding morning than about sustained strain. It changes the baseline hormone level, and testosterone is one of the levels affected by this (IQWiG, 2025).

Physical work is listed as a factor in its own right. In everyday life, this means that someone who does physical work or trained intensively the day before is tested under different conditions than someone after a day at the office.

Alcohol consumption is the factor that is easiest to control. Two alcohol-free evenings before the test cost nothing and remove one unknown from the equation.

When it comes to diet, the issue is not individual foods but eating habits over a longer period. The reviewed source does not give a figure for how much a particular eating pattern shifts the value—so none is provided here.

Medication is the area you should not assess yourself. Which medicines affect the value and to what extent should be discussed with the medical practice that prescribed them.

How to interpret your test result

Your report shows a reference range next to your value. For testosterone, IQWiG gives a range of 2.71 to 10.7 ng/ml for men over 18 and 0.16 to 0.78 ng/ml for women over 18 (2025).

In the second commonly used unit, these are 9.4 to 37.1 nmol/l for men and 0.54 to 2.72 nmol/l for women (IQWiG, 2025). The unit your laboratory uses is shown on the report.

In addition to sex, age also influences these ranges. The same source notes that age also plays an important role (IQWiG, 2025). A value in the lower third at age 25 means something different at age 65.

Two units for the same value

The fact that the same amount is given in two units regularly causes confusion. The number 3 in ng/ml and the number 3 in nmol/l do not describe the same thing.

A look at the ranges shows the difference: For men, they range from 2.71 to 10.7 ng/ml and from 9.4 to 37.1 nmol/l (IQWiG, 2025). The nmol/l figures are therefore about three and a half times higher.

This leads to a simple precautionary rule: never compare a number with a range without placing the unit alongside it. A value of 5 is low-normal in one system and clearly below the range in another.

The unit your laboratory uses is shown on the report, usually directly after the number. When comparing two test results, that is the first thing you should check.

Why a value just outside the range means little

A reference range is not a boundary between healthy and ill, but a statistical range. Its limits are set so that 95 percent of healthy people fall within it (IQWiG, 2025).

Five percent therefore fall outside it, even though there is nothing wrong with them. A value just below the lower limit is therefore a reason to ask questions, not a diagnosis.

What to do about an abnormal value

A value outside the reference range is a reason to investigate, not a result. The sensible sequence begins by asking under what circumstances the sample was collected.

If the sample was taken outside the time window, a second measurement at the correct time is the next step. If it was taken within the window and the value remains abnormal, the finding should be taken to a medical practice.

What happens there is not a repeat of the same measurement, but an interpretation. The value is considered together with your account, your age, your medications, and the other findings.

Take the printed report with you, along with the date and time of the sample. This shortens the conversation and, in the best-case scenario, saves you from a third blood draw.

Those who want to go through a medical practice and find out what their health insurance covers can find this in our article Having hormones tested by your general practitioner. This article focuses on the measurement method itself.

Where you can have the level measured

In addition to having blood drawn at a medical practice, there is the option of using a test that you perform at home and send to a specialized laboratory. The sample then comes from the fingertip instead of the vein in the arm.

mybody®x (MYBODY Lab GmbH) offers such a test for men. It measures total testosterone and also calculates free testosterone because it measures SHBG and albumin as well.

With an at-home test, you determine the timing yourself—that is both the advantage and the responsibility. If you take the sample in the evening, you get a value that has nothing to do with the window between 8 and 10 a.m.

Capillary blood test · for men

HormoneCheck | Men’s hormone test

Ten hormone values, including total testosterone and calculated free testosterone, as well as the two transport proteins SHBG and albumin, along with estradiol, DHEA-S, LH, FSH, prolactin, and TSH. What the test does not do: It does not provide a diagnosis, and it cannot correct for the timing of your sample collection. Take the sample in the morning and note the time.

Price €149.00 As of 27 August 2026, subject to change

Sample type Capillary blood

Processing time Kit shipping 1–3 business days
Laboratory analysis 3–5 business days after sample receipt

Laboratory certified medical laboratory
Product page information, accessed 27 August 2026

For the HormoneCheck for men

What distinguishes capillary blood from venous blood

Capillary blood comes from the smallest blood vessels, the capillaries. A small prick on the fingertip is enough to collect a few drops.

The practical difference lies in the quantity and the collection site. Venous blood is collected in tubes, usually in a medical practice; you can collect capillary blood yourself, but the sample volume is small.

For the analysis, this means that the laboratory determines the same value but uses a different sample type. The reference ranges on the report always relate to the method that was actually used for the measurement.

All mybody®x blood tests use capillary blood. That is why a kit can be sent by mail and no medical practice is needed for sample collection.

Our article Getting a testosterone test explains in detail how such a test works in practice and who it is suitable for. Here, we focus on the procedure behind it.

Which option fits which question

There are three ways to obtain a testosterone level. They are not mutually exclusive, but they answer different questions. The table compares them according to the same five criteria.

The final cell has deliberately been left unnamed. This article contains no verified information on the processing times of laboratories that accept self-paying customers directly.

What a testosterone level does not tell you

A testosterone level does not answer why it is at that level. It shows an amount at a specific point in time. Whether the cause is sleep deprivation, a period of high physical strain, medication, or an illness cannot be determined in the laboratory.

The second limitation is the single measurement. Because the time of day, sleep, alcohol, and physical exertion all influence the level (IQWiG, 2025), a sample also reflects the circumstances of the day on which it was taken.

The third limitation concerns the at-home test: it provides a result, not a diagnosis. An abnormal value should be medically assessed, regardless of how it was obtained.

The fourth limitation concerns what a value says about symptoms. A testosterone level within the reference range does not rule out exhaustion, lack of drive, or declining resilience. These symptoms can have many possible causes, and very few of them show up in a hormone test.

The reverse is also true. A value below the range does not prove that it is the cause of the symptoms. Correlation and cause are two different things, and that distinction is not made by a laboratory value but by a conversation.

There is also a limitation concerning our own content: the reviewed sources do not provide a figure for the typical size of the free fraction relative to total testosterone. That is why this article does not give one.

What ultimately matters

If you take away just one thing from this article, let it be this: Schedule the blood draw in the morning and write down the time. It is one line that determines whether the entire test result is useful.

Everything else in this text is based on that. The reference range, age classification, and comparison with a second measurement all require both samples to have been taken at the same time of day.

It started with the question of how testosterone levels are measured. The short answer is a blood sample. The complete answer is: a blood sample taken at the right time and interpreted using the correct reference range. If you are unsure which value is relevant to your question, our advice is free and does not try to sell you anything.

Frequently asked questions

Sources

1. Institute for Quality and Efficiency in Health Care (IQWiG): Testosterone (2025 edition) – gesundheitsinformation.de
2. Institute for Quality and Efficiency in Health Care (IQWiG): Understanding laboratory values correctly (2025 edition) – gesundheitsinformation.de

The literal quotation on blood sampling, the time window between 8 and 10 a.m., the timing three to five days after the start of menstruation, the information on where the hormone is produced and its functions, the reference ranges in ng/ml and nmol/l, and the influencing factors stress, physical work, alcohol consumption, diet, and medication are taken from source [1]. The information on how reference ranges are established, the 95 percent within and five percent outside the ranges, and their dependence on the laboratory and method are taken from [2]. Information on price, biomarkers, sample type, and laboratory comes from the mybody®x product page, accessed on 27 August 2026; processing times follow the central specifications for blood tests. Both sources were accessed and reviewed on 27 August 2026.

mybody®x Editorial & Expert Team

Laboratory diagnostics Blood analysis interpretation Nutritional science Nutrigenetics

This article was created by mybody®x’s editorial and expert team. The team combines laboratory diagnostics, nutritional science, and the interpretation of blood analyses. Anyone who contributes to it is listed on the authors’ page.

Published on 27 August 2026 · Last updated on 27 August 2026

The content is for general information purposes and does not replace medical advice, diagnosis, or treatment. Reference ranges depend on the laboratory, method, and age; the information on your test report is always decisive.