This article has been medically reviewed by Dr. Jonathan Apasu, physician and founder of Adon Health.
Loss of energy, low libido, less muscle despite hard training? In such situations, determining your testosterone level might be the right next step. Anyone wanting to have their levels tested needs one thing above all: reliable results. But not every test provides an equally meaningful basis for analysis. This article shows you what really matters when measuring testosterone and why blood tests, especially under certain conditions, are considered the gold standard.
Why should you test your testosterone levels?
Testosterone is the most important male sex hormone. Among other things, it influences muscle growth, fat distribution, libido, mood, and energy levels. When levels drop, for example due to age, stress, lack of sleep, poor diet, or illness, this can have far-reaching consequences ( Bhasin et al., 2018 ). Therefore, anyone experiencing symptoms such as fatigue, lack of motivation, loss of libido, or muscle loss should have their hormone levels checked. Even as a general health check without symptoms, a measurement can be useful to establish an individual baseline during healthy years and to have a reliable comparison value later on.
Blood test as the gold standard
Whether it's the Endocrine Society, the American Urological Association, or the European Association of Urology (EAU): all medical guidelines recommend measuring total and free testosterone in the blood, ideally in the morning between 7 and 10 a.m. This is crucial for a valid diagnosis ( Bhasin et al., 2018 ; Mulhall et al., 2018 ; Corona et al., 2020 ).
Saliva and urine tests, on the other hand, provide unreliable results according to studies. Saliva concentrations fluctuate considerably, as they are influenced by numerous external factors such as saliva flow, time of day, and local enzymes. Urine tests, in turn, only detect hormonal breakdown products and not the active hormone itself, which is crucial for diagnosis ( Fiers et al., 2014 ; Lood et al., 2018 ). While these tests may seem easier to determine and are comparatively inexpensive, their interpretation is hardly usable. Furthermore, no therapeutic consequences can be derived from them, as they do not meet clinical standards for diagnosis. For these reasons, medical societies do not recommend either method for diagnosing testosterone deficiency.
Capillary blood vs. venous blood: Which blood draw is appropriate when?
There are two established methods for blood collection to determine testosterone levels: capillary blood, for example via finger prick, and venous blood, classically drawn from a vein in the arm. Both have their place, but also different applications.
Capillary blood test
For a capillary blood test, you take a small blood sample yourself from your fingertip. This method is simple, virtually painless, and can be conveniently performed at home. The sample is then sent to a specialized laboratory.
A major advantage lies in the discretion and independence from a doctor's visit. You can take the test whenever it fits into your daily routine. No travel or waiting time is required. The method is ideal for men who want to easily get initial indications of their hormone levels. Our capillary blood tests at Adon Health are clinically validated and measure the most important biomarkers for men's health – including total and free testosterone, SHBG, LH, and many more.
It's important that you perform the test in the morning on an empty stomach, as testosterone levels are at their highest at this time ( Crawford et al., 2015 ). You should also carefully follow the instructions and allow yourself enough time to stimulate blood flow, for example, by washing your hands with warm water or doing light exercise like jumping jacks. Since the samples are sent to the lab by mail, it may take a little longer to receive your results compared to a venous blood draw. In the height of summer or winter, you should drop off the sample at a parcel shop to ensure temperature-controlled storage and fast shipping. You can find more information on how to perform our blood test correctly in the step-by-step testosterone test guide .
Make sure to use only clinically validated home tests like those from Adon Health. Only these guarantee an accuracy comparable to venous blood sampling in medical laboratories.
Venous blood sampling (traditionally at the doctor's office, hospital or in a direct laboratory)
Venous blood sampling is the gold standard and is performed by medical professionals, usually from a vein in the arm at the crook of the elbow. It is a familiar standard procedure in medical practices and laboratories and requires little preparation. One advantage of this method is that larger volumes of blood can be drawn without the person being tested having to actively participate in the procedure.
Venous blood sampling can be a useful alternative, especially for men in whom capillary blood sampling was difficult or insufficient material was obtained.
However, this method is less flexible in its implementation. It requires a fixed appointment and is tied to the opening hours and availability of the doctor or laboratory. This often involves waiting times, organizational effort, and additional stress. Furthermore, it is not always possible to collect the sample precisely during the ideal time window in the early morning, which can limit the reliability of the results. Many men also find visiting the doctor's office uncomfortable or not very discreet, especially when it comes to sensitive topics such as libido, testosterone, or sexual health.
Interim conclusion:
Capillary and venous blood sampling each have their own advantages. Which method is right for you depends on your individual needs. If you're looking for a discreet, flexible, and scientifically validated way to conveniently determine your hormone levels from home, a capillary blood test may be ideal. It's particularly well-suited for an initial assessment and can also enable more comprehensive health analyses.
Venous blood sampling is particularly suitable if home sample collection was unsuccessful or if very large blood volumes are required. However, it requires a scheduled appointment, is subject to opening hours, and can involve additional effort.
Both methods provide reliable results when performed correctly. It's important that you use clinically validated tests and carefully follow the instructions.
Which values are important and why?
A simple total testosterone level is insufficient to fully assess the hormonal situation. The following laboratory parameters are important for a meaningful evaluation:
- Total testosterone measures the sum of all testosterone forms in the blood, namely free, SHBG-bound, and albumin-bound testosterone. It is the basis of every diagnosis. According to the EAU guidelines, values below 12.1 nmol/L are considered indicative of hypogonadism, provided corresponding symptoms are present ( European Association of Urology, 2025 ).
- Free testosterone is the biologically active form. Only it can bind to receptors and directly affect muscles, brain, or sexual function. A normal total testosterone level can still indicate insufficient free testosterone in the presence of high SHBG levels, a so-called functional deficiency ( Vermeulen et al., 1999 ).
- SHBG is a transport protein. The higher its level, the less testosterone is freely available. Stress, thyroid disorders, or liver disease can influence SHBG levels ( Rosner et al., 2010 ).
- Albumin binds testosterone loosely. This form is also bioavailable. In cases of chronic illness or intense physical exertion, albumin levels can decrease, thus reducing the amount of hormone available ( Mazer, 2009 ).
- LH stimulates testosterone production in the testes. If LH is low despite a testosterone deficiency, the problem likely lies in the pituitary gland. If it is elevated, the testes themselves are not functioning properly. This is important for diagnosing the underlying cause ( Bhasin et al., 2018 ).
- PSA is not a hormone, but a tumor marker. This value should be measured before starting testosterone therapy to rule out existing prostate cancer. PSA is also measured regularly for monitoring disease progression ( Morgentaler et al., 2015 ).
This blog article will provide more information on how to correctly interpret your test results.
Preparation: How to get the most out of your test
To ensure your test result is truly meaningful, you should consider the following points:
- Choose a time between seven and ten o'clock in the morning, because testosterone levels are highest during this phase ( Bhasin et al., 2018 ).
- Also, make sure you don't eat anything for at least eight hours beforehand. Only water is allowed ( Cleveland Clinic, 2022 ).
- You should also avoid alcohol and stimulating substances like caffeine on the morning of the test and the evening before.
- Illness, lack of sleep, or persistent stress can temporarily lower your testosterone levels and distort the test results. For example, just one week of less than five hours of sleep per night can reduce testosterone levels by 10 to 15% ( Leproult & Van Cauter, 2011 ). Chronic stress also leads to elevated cortisol levels, which can inhibit the body's own testosterone production ( Gonzalez et al., 2021 ).
Therefore, perform the test under stable everyday conditions if possible, when you feel healthy and rested.
These recommendations are based on circadian hormone regulation and minimize fluctuations. You can find detailed instructions for taking our capillary blood test here .
Repeated tests for reliable diagnoses
Since testosterone levels fluctuate depending on the time of day and situation, for example due to stress, infections, or lack of sleep, medical guidelines generally recommend two independent tests on different days before a diagnosis is made ( Bhasin et al., 2018 ). Whether a confirmatory test is actually necessary for a diagnosis depends on the biomarkers and results measured in the initial test and is at the discretion of the treating physician.
Conclusion: The best way to achieve hormone clarity
If you want to know your testosterone levels, there's no way around a blood test. Capillary blood tests offer a convenient, reliable, and discreet way to determine your hormone levels. They provide medically relevant data, provided they are used and interpreted correctly.
