What is a Testosterone test?
Your healthcare provider may order a testosterone test if you demonstrate some of the symptoms associated with low testosterone. A health professional can also recommend a precautionary testosterone test if you have a clinical condition that increases the risk of abnormal testosterone levels, such as obesity, type 2 diabetes, chronic obstructive pulmonary disease, and cardiovascular disease.
A testosterone blood test is the withdrawal and assessment of your blood. A healthcare professional will take a blood sample from a vein in your arm using a small needle.
What does a Testosterone test measure?
Testosterone tests differ. Some tests are relatively simple, measuring only your total testosterone level. It is common for health professionals to start here - known as a ‘screening test’. However, if you are a “grey area” patient, a health professional will require more detailed information and suggest a more comprehensive test.1
In addition to total testosterone levels, comprehensive tests may also measure:
- Free testosterone - bioavailable testosterone that is not attached to any protein.
- Sex-hormone binding globulin (SHBG) - a protein that attaches to testosterone and inhibits testosterone use.
- Luteinising hormone (LH) - binds to specific cells in the testes to stimulate testosterone production.
- Follicle-stimulating hormone (FSH) - critical to producing sperm cells.
Interpreting your Testosterone results
A healthcare professional should discuss your testosterone test results with you. If not, we encourage you to prompt such a discussion – it is important to understand how your results relate to your symptoms, general health, and long-term disease risk.
Below, we summarise each result and the possible implications.
Total Testosterone in adult men
Normal testosterone levels:
- 10.4 nmol/L and 34.7 nmol/L (300 to 1,000 ng/dL)
Low testosterone levels:
- Below 10.4 nmol/L (300 ng/dL)
High testosterone levels:
- Above 34.7 nmol/L (1,000 ng/dL)
What do the Total Testosterone results mean?
If initial testosterone results are high or low, a health professional will usually recommend a repeat test in the following weeks. Up to 30% of patients with initially abnormal testosterone values have normal levels on repeat testing.2
High testosterone levels are associated with acne, oily skin, excessive hair growth, prostate enlargement, mood swings, aggression, and increased muscle mass. The possible causes of high testosterone include steroid use, testicular tumours, and adrenal gland disorders.
Low testosterone levels are associated with a low sex drive, erectile dysfunction, muscle and bone mass loss, and a lack of hair growth. The possible causes of low testosterone levels include ageing, chronic disease, short-term illness, medication, testicular injury, non-cancerous tumours, certain genetic diseases, and alcohol use disorder.
- A low testosterone result does not necessarily mean that you have a medical condition or need treatment. It is possible to have low testosterone without symptoms, and it is normal for testosterone levels to decrease gradually with age.3 Based on current guidelines, you will only be diagnosed with testosterone deficiency if you first present with clinical signs or symptoms of low testosterone and there is no easily reversible cause, such as medication or acute illness.
The diagnosis of hypogonadism is strictly based on unequivocal and consistently low testosterone levels in combination with symptoms and signs of low testosterone.4
Sex Hormone-Binding Globulin (SHBG)
Normal SHBG levels:
- 10 – 57 nmol/L
Low SHBG levels:
- Below 10 nmol/L
High SHBG levels:
- Above 57 nmol/L
What do the SHBG results mean?
Measuring your SHBG level provides information about how much of your testosterone is active. Only testosterone that is free or attached to albumin is considered available for use.
Typically, a health professional will be clinically concerned with either the combination of low to moderate testosterone and high SHBG, or high testosterone and low SBHG. Both varieties suggest an abnormality in the level of bioavailable testosterone. However, whether a high or low SHBG level is concerning in your case depends on how a health professional interprets this result with your symptoms and other results (total and free testosterone levels).
Abnormal SHBG levels link with a range of health conditions: metabolic syndrome and type 2 diabetes,5 hypothyroidism,6 cirrhosis,7 and stroke.8
Bioavailable testosterone includes testosterone that is free or loosely attached to albumin. Because of this, free testosterone is theorised - although still debated - to be a good proxy for how much of your testosterone is actively working. Since low free testosterone levels can associate with symptoms of low total testosterone, even when total testosterone levels are normal, this additional measure provides important information.9
It is difficult, however, for clinicians to directly measure free testosterone.10 Most laboratories use an equation to calculate it indirectly based on total testosterone and other values, such as SHBG and albumin. For this reason, there is still no consensus on the ‘normal range’ of free testosterone; different guidelines recognise different free testosterone ranges as normal or abnormal. A general rule of thumb is that free testosterone less than 50–65 pg/mL is considered low.
We encourage you to discuss your free testosterone result with a health professional. A clinical interpretation of this result will differ case-by-case, depending on a host of other factors.
Luteinizing Hormone (LH)
In men ages between 20 and 70 years of age
Normal LH levels:
- 0.7 - 7.9 IU/L
Low LH levels:
- Below 0.7 IU/L
High LH levels:
- Above 7.9 IU/L
In men above the age of 70 years
Normal LH levels:
- 3.1–34.0 IU/L
Low LH levels:
- Below 3.1 IU/L
High LH levels:
- Above 34.0 IU/L
Follicle-Stimulating Hormone (FSH)
Normal FSH levels:
- 1.5 - 12.4 IU/L
Low FSH levels:
- Below 1.5 IU/L
High FSH levels:
- Above 12.4 IU/L
What do the LH and FSH results mean?
Health professionals use LH and FSH readings to explore a possible cause of low testosterone and diagnose hypogonadism.
When LH and FSH levels are both high, this suggests the pituitary gland is working excessively to produce testosterone when the testes are either impaired or damaged. For this reason, a high LH and FSH level indicates testicular failure and, in combination with low total testosterone, is used to diagnose primary hypogonadism.11
On the other hand, whereas the pituitary works in overdrive in primary hypogonadism, secondary hypogonadism centres on defects in the brain or pituitary that result in insufficient/low LH and FSH production. Secondary hypogonadism is therefore associated with low or low-normal LH and FSH levels.12
Aside from the diagnosis of hypogonadism, low FSH is also commonly associated with low sperm production and male infertility.13 A health professional will likely proceed with other tests in this case.
Interesting in learning more about testosterone treatment? Read our breakdown of the treatment options available here
- It is important to discuss your testosterone test results with a health professional.
- An abnormal testosterone result does not necessarily mean that you have a medical condition or need treatment.
- Low and high testosterone levels indicate a potential health concern; however, when symptoms of abnormal testosterone are apparent despite normal total testosterone levels, tests for SHBG, free testosterone, LH, and FSH will provide more context.
Join the conversation on the TRTed Community!
- Bhasin S et al. J Clin Endocrinol Metab 2010;95(6):2536-59.
- Crawford DE et al. BJU Int 2007;100(3):509-13.
- Wu F, et al. J Clin Endocrinol Metab 2008;93(7):2737-45.
- Bhasin S et al. J Clin Endocrinol Metab 2018;103(5):1715-1744.
- Le TN et al. Trends Endocrinol Metab 2013;23(1):32-40
- Hampl R et al. Thyroid 2003;13(8):755-60.
- Maruyama Y et al. Gastroenterol Jpn 1991;26(4):435-9.
- Madsen TE et al. Stroke 2020;51(4):1257-1264.
- Antonio L et al. J Clin Endocrinol Metab 2016;101(7):2647-57.
- Keevil BG, Adaway J. J Steroid Biochem Mol Biol 2019;190:207-211.
- Dandona P, Rosenberg MT. Int J Clin Pract 2010;64(6): 682–696.
- Lenzi A et al. J Endocrinol Invest 2009;32(11):934-8
- Behre HM. Front Endrocrinol (Lausanne) 2019;24;10:322.