By Eric Ruiz, MSN, APRN, FNP-BC, RNC-OB · Family Nurse Practitioner, Axis Health
Feeling tired all the time, losing interest in sex, or noticing that workouts don't pay off the way they used to? Many men wonder whether low testosterone ("low T") is to blame. Sometimes it is, and sometimes something else is going on. Here's how to tell the difference, and why a simple blood test is the only way to know for sure.
What Is Low Testosterone?
Testosterone is the main male sex hormone. It supports sex drive, erections, muscle and bone strength, red blood cell production, energy, and mood. Levels naturally decline slowly with age, but some men drop low enough to cause symptoms. Doctors call this testosterone deficiency or male hypogonadism.
The American Urological Association (AUA) defines testosterone deficiency as low testosterone levels combined with symptoms or signs that go along with it. A low number on its own, or symptoms on their own, isn't enough to make the diagnosis.
Common Symptoms of Low T
The most specific signs involve sexual health. According to the Endocrine Society's clinical guideline, symptoms that point more strongly toward low testosterone include:
Low sex drive (libido)
Fewer spontaneous or morning erections
Erectile dysfunction
Breast tenderness or enlargement
Loss of body hair or needing to shave less often
Very small or shrinking testes
Low bone density or a fracture from a minor injury
Hot flashes or sweats
Other symptoms are common but less specific, meaning they can have many causes:
Fatigue and low energy
Low mood, irritability, or trouble concentrating
Reduced muscle mass and strength
Increased body fat, especially around the waist
Poor sleep
Reduced motivation or drive
Why Symptoms Alone Aren't Enough
Many of these symptoms overlap with other conditions, including depression, thyroid disease, sleep apnea, diabetes, chronic stress, poor sleep, excess alcohol, and side effects of certain medications such as opioids. That's why a proper evaluation looks at the whole picture rather than jumping straight to treatment.
How Low Testosterone Is Diagnosed
Diagnosis requires both symptoms and confirmed low blood levels. Current guidelines recommend:
Morning blood tests. Testosterone is highest in the early morning, so blood should be drawn then (ideally before about 10 a.m.).
At least two separate tests. Levels vary from day to day, so a low result should be repeated on a different morning to confirm it.
A clear cutoff. The AUA uses a total testosterone level below 300 ng/dL as a reasonable cutoff to support the diagnosis.
Testing when you're well. Acute illness can temporarily lower testosterone, so testing is best done when you're otherwise healthy.
Depending on your results, your provider may also check luteinizing hormone (LH), prolactin, a complete blood count, PSA, and other labs. These help find the cause of low testosterone and make sure treatment would be safe for you.
When Should You Get Checked?
Consider an evaluation if you have:
Ongoing low libido or erectile changes
Persistent fatigue that doesn't improve with better sleep and lifestyle changes
Type 2 diabetes, obesity, or a history of using opioids or anabolic steroids
A history of testicular injury, chemotherapy, or pituitary problems
Unexplained bone loss or a low-impact fracture
What Happens Next?
If testing confirms low testosterone, the next step is a conversation about your goals, your health history, and your options. Testosterone therapy isn't right for everyone. For example, men who are trying to conceive need a different approach, because testosterone therapy can lower sperm production. If treatment is started, it should include regular follow-up and lab monitoring to keep it safe and effective.
Get Answers at Axis Health
At Axis Health in Wilbraham, MA, every evaluation starts with a one-on-one consultation, a review of your symptoms and health history, and in-office lab work. If you've been wondering whether low T could be behind how you feel, we can help you find out. Book a consultation or learn more about our testosterone therapy services.
This article is for general education and isn't a substitute for personal medical advice. Talk with a qualified healthcare provider about your symptoms and treatment options.
References
Mulhall JP, Trost LW, Brannigan RE, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline. J Urol. 2018;200(2):423-432. Validity confirmed 2024. auanet.org
Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715-1744. PubMed
Cleveland Clinic. Low Testosterone (Male Hypogonadism). clevelandclinic.org