Testosterone Plus is an extended health check for those who want a more comprehensive picture of their testosterone levels and the body's hormonal regulation. The test covers total testosterone, SHBG, calculated free or bioactive testosterone, as well as supplementary hormones and blood markers that provide a broader basis for assessing your testosterone status.
Testosterone is the primary male sex hormone and plays a role in factors such as libido, erectile function, muscle mass, bone health, red blood cell production, and general well-being. However, symptoms like fatigue, reduced libido, and impaired physical performance can have many other causes. Therefore, the result of a testosterone test must always be evaluated in conjunction with symptoms, age, medications, lifestyle habits, and medical history.
What is included in Testosterone Plus?
Testosterone Plus includes several relevant biomarkers that, together, provide a broader picture of testosterone levels and the body's hormonal regulation than a single testosterone test.
Total Testosterone – S-Testosterone
Total testosterone indicates the combined amount of testosterone in the blood, encompassing both protein-bound and free testosterone. S-Testosterone is typically the primary analysis used to assess testosterone levels and investigate suspected low testosterone. However, a single testosterone value is not sufficient to diagnose testosterone deficiency. A low or borderline result generally needs to be evaluated alongside symptoms and may require verification with a new morning sample.
SHBG
Sex hormone-binding globulin (SHBG) is a transport protein that binds a large proportion of the testosterone in the blood. SHBG levels influence the distribution between bound and available testosterone and can therefore provide important information when interpreting total testosterone levels. SHBG levels can be affected by factors such as age, body weight, liver function, thyroid function, medications, and various hormonal conditions. Consequently, a testosterone level that appears normal may need to be assessed alongside SHBG to provide a more nuanced picture of testosterone status.
Calculated free or bioactive testosterone
Only a small fraction of the testosterone in the blood circulates in a completely unbound state. By combining total testosterone with SHBG and—depending on the laboratory's calculation method—albumin, the amount of free or bioavailable testosterone can be estimated. Calculated testosterone can provide supplementary information, particularly when total testosterone levels are close to a clinical threshold or when SHBG levels are unusually high or low.
Terminology may vary between laboratories. "Free testosterone" refers to the unbound fraction of testosterone, whereas "bioactive" or "bioavailable" testosterone typically encompasses free testosterone plus the fraction loosely bound to albumin. The specific analysis method and terminology used by the laboratory are indicated in the test results.
Lutropin – LH
LH (lutropin) is a hormone produced in the pituitary gland that stimulates the testes to produce testosterone. The combination of testosterone and LH levels can provide important information about the body's hormonal regulation. Low testosterone combined with elevated LH may indicate impaired testicular function. Conversely, low testosterone combined with low or normal LH levels may warrant further assessment of the pituitary gland's hormonal regulation and other potential causes.
Prolactin
Prolactin is a hormone produced by the pituitary gland and plays a role in the body's hormonal regulation. In men, elevated prolactin levels can affect signaling between the pituitary gland and the testes, potentially contributing to reduced testosterone production. This analysis can provide supplementary information in cases involving low testosterone levels, reduced libido, erectile dysfunction, or fertility issues. Prolactin levels are particularly relevant when low testosterone coincides with low or normal LH levels. Prolactin levels can be temporarily influenced by factors such as stress, sleep, physical activity, and certain medications. Therefore, an elevated result must be evaluated in the context of other hormone levels, symptoms, and medical history, and may sometimes require verification with a follow-up test.
Complete Blood Count (CBC)
A complete blood count (CBC) measures parameters such as hemoglobin, red and white blood cells, and platelets. The analysis can identify conditions such as anemia and other abnormalities that may contribute to fatigue or low energy levels. Hemoglobin and hematocrit levels are also important for monitoring testosterone therapy, as such treatment can increase red blood cell production.
When might a testosterone test be relevant?
Testosteron Plus may be relevant for men who are experiencing symptoms consistent with low testosterone levels, wish to gain a broader overview of their hormonal status, or want to follow up on a previous testosterone reading that was low or difficult to interpret. Examples of symptoms and situations where a testosterone test might be considered include:
- reduced libido.
- fewer spontaneous morning erections.
- erectile dysfunction.
- reduced muscle mass or strength.
- pronounced fatigue or low energy.
- impaired physical performance.
- low mood or reduced motivation.
- difficulty concentrating.
- fertility issues.
- previously low or ambiguous testosterone levels.
- monitoring of ongoing testosterone treatment.
Many of these symptoms are non-specific and can also occur due to factors such as sleep deprivation, stress, depression, excess weight, thyroid disorders, chronic illness, or medication. Therefore, while the testosterone test provides valuable information, the results must always be evaluated within the broader clinical context.
How are testosterone levels interpreted?
Testosterone levels are assessed based on the laboratory's reference range, the time of sampling, symptoms, and other hormone test results. A single low testosterone reading is not sufficient to establish a diagnosis of testosterone deficiency. In the event of a low or borderline result, it is usually recommended to re-check total testosterone levels on a separate occasion. A diagnosis of testosterone deficiency—also known as hypogonadism—typically requires the presence of both relevant symptoms and consistently low testosterone levels.
Why are testosterone and SHBG analyzed together?
Most of the testosterone in the blood is bound to SHBG or albumin, while only a small fraction circulates completely freely. Changes in SHBG levels can therefore affect total testosterone without a corresponding change in the amount of available testosterone. Assessing total testosterone alongside SHBG and calculated free or bioactive testosterone can, in certain situations, provide a more complete picture than measuring total testosterone alone.
What does the combination of testosterone and LH indicate?
Together, testosterone and LH levels can provide clues as to where in the hormonal system a potential imbalance might lie. Low testosterone combined with high LH may suggest that the testes are not responding normally to stimulation from the pituitary gland. Conversely, low testosterone accompanied by low or normal LH levels may indicate reduced stimulation from the pituitary gland or hypothalamus, though it can also result from functional factors such as illness, excess weight, or certain medications.
The results cannot determine the cause on their own, but they can indicate whether further hormonal or medical investigation is warranted.
When during the day should the testosterone test be taken?
Testosterone levels fluctuate throughout the day and are typically highest in the morning. To ensure results are as comparable and reliable as possible, men are advised to have their testosterone sample taken between 7:00 AM and 10:00 AM. Food intake can temporarily affect testosterone levels. You must therefore fast before the test and avoid eating from 10:00 PM the evening before the sampling. Drinking water is permitted.
Strenuous physical exercise, acute illness, sleep deprivation, and high alcohol consumption can also affect hormone levels. Therefore, please avoid intense exercise and large amounts of alcohol the day before the test. If possible, the sample should not be taken during an ongoing acute illness.
How the Testosterone Plus result is assessed
Testosterone Plus provides a broad overview of testosterone levels and the body's hormonal regulation; however, this health check alone cannot establish a diagnosis of testosterone deficiency. The diagnosis is based on a combination of relevant symptoms, repeated hormone tests, and a medical assessment. A physician's report is always included if you wish. If your test results indicate testosterone deficiency and you also have symptoms consistent with hypogonadism, we offer further consultation with an external healthcare provider to assess the need for further investigation.
Do not start testosterone treatment or use hormonal preparations based solely on a single test result. Testosterone treatment requires medical assessment and follow-up, and it can also reduce the body's sperm production and affect fertility.
Important information regarding calculated testosterone and choice of laboratory
Laboratories may use different analysis and calculation methods for free and bioactive testosterone. This means that both the terminology and the way the result is reported may differ depending on the laboratory you choose.
Note!
When samples are collected at a clinic affiliated with Karolinska University Laboratory, the calculation of bioactive/calculated free testosterone is not performed if S-Testosterone exceeds 20 nmol/L. If you wish to ensure that a calculated testosterone value is reported even when S-Testosterone exceeds 20 nmol/L, we therefore recommend choosing a collection site affiliated with SYNLAB or Unilabs.
