Testosterone levels are determined through a blood test, as testosterone uses the blood stream to travel around your body. The amount of testosterone in your blood is measured in several different ways.
In the US, testosterone is measured in nanograms per decilitre of blood (ng/dL). Typically, levels of around 264–914 ng/dL (according to one landmark study) are considered normal in healthy adult men. You can see that it allows for a lot of variation!
In the UK, testosterone tends to be measured in nanomoles per litre (nmol/L) for total testosterone (all the testosterone in your blood) and in picomoles per litre (pmol/L) for free testosterone (the testosterone that is available for your body to use).
Levels of total testosterone higher than 12 nmol/L or free testosterone higher than 225 pmol/L are considered normal.
Interestingly, your testosterone levels change a lot over the course of the day. They are highest in the morning (so most blood tests to measure testosterone usually take place then) and drop when you’ve just had a meal.
How Do Testosterone Levels Change with Age?
Your testosterone levels peak in your late teens, around 17–19 years old. However, your levels generally stay high for the next couple of decades. Healthy young men produce about 6mg of testosterone every day.
Around the age of 30 your testosterone levels naturally begin to decline, but it’s a very gradual process. For most men it’s a decrease of only 1% per year. By the age of 70 the testosterone production of the average man is 30% below its peak. Yet it’s estimated that at least 75% of older men still have testosterone levels in the normal range.
Here are the results of one endocrinology study, demonstrating how testosterone levels decline in healthy men after the age of 40 (figures are for total testosterone in the body):
Testosterone levels in 40s: 252–916 ng/dL
Testosterone levels in 50s: 215–878 ng/dL
Testosterone levels in 60s: 196–859 ng/dL
Testosterone levels in 70s: 156–819 ng/dL
So, you can see that older men may have lower testosterone levels than the average for men as a whole, while still being in good health overall.
How Can I Know if I Have Low Testosterone Levels?
While it’s perfectly possible for your testosterone to be on the lower end of “normal” without it impacting your health, if your testosterone levels drop below that range you may experience some health problems.
Symptoms of Low Testosterone
The symptoms of low testosterone (sometimes called “low-T”) reflect the role that the hormone plays in your body. As testosterone is essential for your fertility, energy levels, and muscle and bone strength, low-T can impact these areas of your health.
You may suffer from:
- Loss of sex drive and erectile dysfunction
- Fatigue and problems sleeping
- Decreased muscle mass and brittle bones
- Loss of body and facial hair
- Depression, irritability, or memory loss
If you are experiencing some of these symptoms, you can always visit your GP and ask to have your testosterone levels checked. They will consult with you about your symptoms and may recommend a blood test. Your doctor will consider whether or not your testosterone levels meet the threshold to need treatment, based on two morning fasting blood tests – plus a physical assessment and symptom check.
It’s worth bearing in mind that many of the symptoms above can be the result of lifestyle issues such as poor diet, lack of exercise, or smoking. Your doctor might recommend making changes here, to see if that improves your symptoms, before suggesting treatment for low testosterone. Testosterone levels can also be affected by underlying health conditions such as diabetes, liver disease, or kidney disease.
Treatment for Low Testosterone
The treatment for low-T is known as Testosterone Replacement Therapy (TRT). TRT involves delivering extra testosterone to your body so that your levels of the hormone can recover, causing your symptoms to ease.
In TRT, the testosterone is usually administered via an injection, gel, or skin patch. With the gel, it’s important that women and children don’t touch the area too soon after it has been applied – in order to avoid transfer and potential harm.
Treatment can be for the long term, if your body doesn’t recover the ability to produce enough testosterone for good health. In addition, it’s important to talk to your doctor about the potential risks of TRT, which include prostate enlargement, greater risk of blood clots, and poor cardiovascular health. That way you can make an informed decision.
Key Takeaways
Normal testosterone levels naturally decline with age: what’s typical at 19 isn’t typical at 59. As the decrease in testosterone is so gradual, most men won’t experience severe symptoms. However, if you are concerned that you may have the symptoms of low-T, you’ve got nothing to lose by consulting with your doctor and putting your mind at rest.
FAQs
What is testosterone?
Testosterone is a hormone found predominantly in the male body, and is crucial to the development of the male sex organs, as well as the growth of body hair and muscle mass, and the driving of the libido (or sex drive).
What are normal testosterone levels?
Testosterone levels can vary widely from man to man, with the ‘normal’ or healthy range of testosterone in adult men being around 264–914 ng/dL (US measurement: nanograms per decilitre of blood). Normal, healthy levels change with age, from 252–916 ng/dL in your 40s to 156-819 ng/dL in your 70s.
Why do testosterone levels decrease with age?
Testosterone levels naturally decrease as men grow older, but at a very slow, almost unnoticeable rate (around 1% loss each year, after about the age of 30). Testosterone is crucially important to men during puberty, but becomes relatively less important in later years, hence its declining levels in the body.
What do I do if I have low testosterone levels?
Sometimes low testosterone levels can cause problems, such as a loss of sex drive and erectile dysfunction, problems with energy and sleeping, decreased muscle mass, brittle bones, loss of body and facial hair, and even depression, irritability, and/or memory loss. If you are experiencing any of these symptoms, see a doctor. You may be recommended to make lifestyle changes such as increasing exercise, improving diet, or quitting smoking. However, Testosterone Replacement Therapy (TRT) is an option for men whose low T-levels are not so easily improved.
¹Thomas G. Travison, Hubert W. Vesper, Eric Orwoll, Frederick Wu, Jean Marc Kaufman, Ying Wang, Bruno Lapauw, Tom Fiers, Alvin M. Matsumoto, Shalender Bhasin (2017). Harmonized Reference Ranges for Circulating Testosterone Levels in Men of Four Cohort Studies in the United States and Europe: https://academic.oup.com/jcem/article/102/4/1161/2884621
²Harvard Men’s Health Watch – Testosterone, aging, and the mind: https://www.health.harvard.edu/newsletter_article/testosterone_aging_and_the_mind
While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.
