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A testosterone test sounds simple. You get a number, and it’s either high, low, or normal, right? Well, not quite. Testosterone is trickier than that. It’s key for sexual development, fertility, muscle health, bone health, and overall well-being.
But there’s no single “right” number for every man. Your level depends on your age, the time of day you were tested, and even which lab ran your blood. And studies confirm this. One study looked at men between 20-44 years and found that total testosterone dropped by about 0.14 nmol/L each year.
So, before you check your number against a chart, let’s break down what testosterone does, how it’s tested, and what your results might mean.
Key takeaways
- Testosterone naturally drops as you age. It also shifts during the day — morning levels are usually the highest.
- There isn’t one “normal” number for a testosterone test. Ranges vary by age, lab, and test method. But many labs use about 264-916 ng/dL (9.2-31.8 nmol/L) for healthy men aged 19-39.
- Testing is usually a morning blood draw, sometimes on an empty stomach. It may check total, free, or bioavailable testosterone.
- Low testosterone can cause low sex drive, tiredness, and less muscle mass.
- High testosterone is rare and can come from testosterone therapy, supplements, or a health condition.
- One odd result usually isn’t enough for a diagnosis. Your doctor will likely retest and look at your symptoms, too.
What is testosterone, and what does it do?
Testosterone is the main male sex hormone. It drives male sexual development.
The testes make more than 95% of the testosterone in your blood. Your adrenal glands make other hormones that can turn into testosterone too.
Your brain controls how much testosterone you make. It sends signals to the pituitary gland. The pituitary gland then signals the testes to make testosterone. This back-and-forth is called a feedback loop, and it keeps your testosterone levels in check. When testosterone gets too high, the brain tells the pituitary to slow down, and vice versa.
During puberty, testosterone drives big changes. It:
- Helps the testicles drop
- Starts sperm production
- Grows the penis and testes
- Drives a normal sex drive
Testosterone shapes other traits, too, like:
- Body hair
- A deeper voice
- Growth spurts
- Muscle growth
- Red blood cell production
- Steady mood
Testosterone usually peaks around age 20. After that, it slowly drops. As men age, they may notice smaller testicles and a lower sex drive. Lower testosterone can also mean:
- Less muscle
- Weaker bones
- Fewer red blood cells
Additionally, body fat often creeps up as testosterone goes down.
How is testosterone tested, and why?
The main way to check is with a testosterone blood test. This involves a blood draw, usually in the morning when testosterone is the highest. The draw takes just a few minutes and may cause a bit of discomfort, but it doesn’t last.
You can also test at home. Some kits let you collect a saliva or blood sample, which is then mailed to the lab. If you try one, follow the instructions closely. And always talk to your doctor about what the results mean.
It’s also important to know that there are different types of testosterone tests. This is because testosterone doesn’t float freely in your blood. It attaches to proteins, mainly albumin and sex hormone-binding globulin (SHBG). A tiny fraction remains free and active. Typically, SHBG holds testosterone tightly, while albumin holds it loosely. Free testosterone, plus the loosely held part, is called the “bioavailable” testosterone.
If you need to get your testosterone levels checked, your doctor might order one of these tests:
- Total testosterone: Measures all the testosterone in your blood, which includes the protein-bound component and the free component. This is usually the first test.
- Free testosterone: Useful when total testosterone is borderline, or when something affects sex hormone-binding globulin (SHBG) and makes the total number hard to read.
- Bioavailable testosterone: Used less often. Doctors may order it when SHBG looks off, or if free testosterone can’t be measured well.
Doctors often order a testosterone test if you:
- Have symptoms of testosterone imbalance (such as low libido, erectile dysfunction, fertility issues, etc.)
- Have had an abnormal testosterone level test before
- Take medicine that affects testosterone
- Use hormone therapy
In kids and teens, it can also help explain early or late puberty.
What are normal testosterone levels?
Here’s the truth: there’s no single normal number. Results change based on your age, the lab’s method, and the range that the lab uses.
One large study that compared labs between healthy non-obese men aged 19-39 found a range of about 264-916 ng/dL (9.2-31.8 nmol/L). Other research puts the adult range between 270 and 1,070 ng/dL, depending on age. Another source says the typical range is 300-1,000 ng/dL (10-35 nmol/L).
Let’s take a look at a study of over 1,000 men that tracked average testosterone by age chart (nmol/L):
Age (years) | Total testosterone (nmol/L) |
20-29 | 20.68 |
30-39 | 18.77 |
40-49 | 16.66 |
50-59 | 15.89 |
60-69 | 15.62 |
70+ | 12.28 |
Another study of men 20-44 found that normal testosterone levels in males (ng/ml) drop steadily with age:
Age (years) | Middle range of total testosterone (ng/dL) | Age-specific low-T cutoff (ng/dL) |
20-24 | 409–558 | 409 |
25-29 | 413–575 | 413 |
30-34 | 359–498 | 359 |
35-39 | 352–478 | 352 |
40-44 | 350–473 | 350 |
A separate study of men aged 40-79 also found testosterone dropping with age. Here’s what they found:
Age (years) | 95% reference range (ng/dL) |
40-49 | 251–914 |
50-59 | 216–876 |
60-69 | 196- 859 |
70-79 | 156-818 |
The researchers were clear about one thing: your health and habits matter, too. So these charts should not be read alone. Think of these numbers as examples, not hard rules. Your own lab’s range, plus your doctor’s read on your symptoms, matters more than any chart.
What factors affect testosterone levels?
The following things can affect your testosterone test.
Time of day
Testosterone rises and falls each day, especially in younger men. Testosterone levels are usually highest early in the morning and drop as the day goes on. In young men, evening levels can be 15-20% lower than morning levels, sometimes even more. That’s why doctors usually test between 8 and 10 AM. In fact, most normal ranges were built around morning testing. Doctors often ask you to fast before the test, too.
Age
As we talked about earlier, testosterone tends to drop as you get older.
Sex hormone-binding globulin (SHBG)
Changes in SHBG can change how your total testosterone result should be read. Low sex hormone-binding globulin can happen with:
- Obesity
- Insulin resistance
- Liver disease
- Type 2 diabetes
This can cause a low total testosterone reading, even if you don’t actually have low testosterone. In these cases, checking free testosterone can help clear things up.
What do abnormal testosterone results mean?
Abnormal testosterone levels don’t always mean something is wrong. Testosterone levels shift with time of day, illness, medicine, and even the test method. So results are best read along with your symptoms and health history.
Low testosterone
A low level, plus symptoms of low testosterone, may point to a condition called hypogonadism. Low testosterone usually has two causes. Either:
- The testes aren’t making enough (from injury, infection, chemo, radiation, or a genetic condition)
OR - The brain and pituitary gland aren’t sending strong enough signals (from pituitary problems, certain medicines, or other issues).
The following are also linked to low testosterone:
- Obesity
- Type 2 diabetes
- Serious illness
- Drugs like opioids and steroids
Signs of low testosterone include:
- Low sex drive
- Trouble with erections (erectile dysfunction)
- Tiredness
- Less muscle
- Mood changes
High testosterone
This is less common in adult men. Possible causes include:
- Testosterone therapy or steroid use
- Tumors on the adrenal glands or testicles
- Genetic condition called congenital adrenal hyperplasia
- Hyperthyroidism
Signs of high testosterone include:
- Acne
- Mood swings
- Enlarged prostate
A high result is usually retested, and your doctor will look at your medicines, symptoms, and other hormone levels, too.
Know more: What are the Signs of High Testosterone in a Man?
What should you do next?
If your testosterone test comes back low, your doctor will likely repeat the test in the morning to make sure.
A diagnosis of low testosterone should be based on symptoms plus more than one low reading, not just one test.
If a testosterone deficiency is confirmed, more tests like luteinizing hormone (LH) and follicle-stimulating hormone (FSH) can help find out if the problem starts in the testes or in the brain and pituitary gland.
If your testosterone test comes back high, your doctor will probably check any testosterone medicine, steroids, or supplements you’re taking. And then retest. More hormone tests or scans may follow if your testosterone levels stay high or your doctor suspects a health condition.
Either way, remember this: one number does not tell the whole story. Your symptoms, when you were tested, repeated results, and other hormone levels all matter too.
Conclusion
A testosterone test can tell you a lot, but only with the full picture. Normal testosterone is a range, not one fixed number. And that range shifts with age, the test method, and who the lab studied to build it.
If your doctor orders a testosterone test, expect a morning blood draw. And know that a low result usually gets retested before anyone calls it low testosterone. If low testosterone is confirmed, tests like luteinizing hormone (LH) and follicle-stimulating hormone (FSH) can help find the cause.
The goal isn’t just to learn if your testosterone is “high” or “low.” It’s to understand what that number means for you.
FAQs
The standard way is a morning blood test that checks total testosterone. Some at-home kits let you collect a blood or saliva sample yourself and mail it to a lab. If your results are borderline, your doctor may also check free or bioavailable testosterone.
It depends on why your testosterone levels are low in the first place. Things like your weight, sleep, and certain medicines can play a role. But the right next step depends on your specific cause. This is why testing and a talk with your doctor should come first.
Common signs of low testosterone include:
- Low sex drive
- Trouble with erections (erectile dysfunction)
- Tiredness
- Less muscle mass
- Mood changes
These signs overlap with other health issues too. That’s why a low test result plus these symptoms is what usually points to a diagnosis.
Signs your testosterone levels are in a healthy range include:
- A normal sex drive
- Steady mood and energy
- Typical muscle mass for your age
“Good” testosterone levels really just mean levels that fit your age and health.
The cost depends on your provider, your insurance, and whether you go through a doctor’s office or an at-home kit. Prices vary a lot, so it’s worth checking with your insurance and lab directly.
There’s no single cutoff for everyone. But unexpectedly high testosterone levels, especially with signs like acne, mood swings, or an enlarged prostate, is usually retested.
Your doctor will look at your medicines and other hormone levels too, not just one number.
At-home kits usually need a small blood or saliva sample that you collect yourself and mail to a lab. Follow the kit’s steps closely, and always review your results with a doctor instead of reading them alone.
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- Age-related decline in total testosterone levels among young men: insights from a large single-center observational study | Nature
- Physiology, Testosterone | NIH
- Laboratory Assessment of Testicular Function | NIH
- Total Testosterone | University of Rochester Medicine
- What Is a Normal Testosterone Level for Young Men? Rethinking the 300 ng/dL Cutoff for Testosterone Deficiency in Men 20-44 Years Old | American Urological Association
- Falsely elevated serum testosterone measurements resulting from testosterone topical gel contamination of the venipuncture site: Case Series and retrospective review | ScienceDirect
- Testosterone Levels Test | MedlinePlus
- Evaluation and Management of Testosterone Deficiency (2024) | American Urological Association
- Harmonized Reference Ranges for Circulating Testosterone Levels in Men of Four Cohort Studies in the United States and Europe | Oxford Academic
- The prevalence of low sex steroid hormone concentrations in men in the Third National Health and Nutrition Examination Survey (NHANES III) | PubMed Central
- Hypogonadism in Men | Endocrine Society
- Testosterone Deficiency | JAMA Network
- Hormonal treatment of acne vulgaris: an update | PubMed Central
- A surprising diagnosis in a man with high testosterone levels | Endocrine Abstracts
- Testosterone Therapy for Hypogonadism Guideline Resources | Endocrine Society
