Key takeaways
- Low energy, low mood, and poor sleep have many causes. Among common symptoms, the ones tied most closely to low testosterone are sexual: lower desire, fewer morning erections, and erectile dysfunction.
- A diagnosis takes both symptoms and consistently low levels on two fasting, morning blood tests. About 30% of men with one low result test normal on repeat.
- Guidelines set the lower limit of total testosterone at 264 or 300 ng/dL. Free testosterone and SHBG clarify a borderline result; LH and FSH show where the problem starts.
- Obesity, illness, and medications such as opioids can suppress testosterone, and addressing the cause can raise it.
- FDA-approved testosterone is for men whose low levels come with an associated medical condition. Its safety and efficacy for age-related low testosterone have not been established, and compounded testosterone is not FDA-approved.
Tired by mid-afternoon. Less interest in sex. Workouts that don't pay off the way they used to. Many men over 40 wonder whether low testosterone is behind it. Sometimes it is. Often something else is going on. The way to find out is to match your symptoms with properly timed blood tests.
Which symptoms actually point to low testosterone
The most familiar symptoms are also the least specific. The Endocrine Society lists low energy, low motivation, depressed mood, poor concentration, disturbed sleep, reduced muscle, and increased body fat as nonspecific. They occur with low testosterone, and also with obesity, sleep apnea, depression, and other medical conditions.
Among common symptoms, the ones tied most closely to testosterone are sexual. The European Male Ageing Study surveyed men aged 40 to 79 about a range of symptoms. Only three tracked consistently with low levels: lower sexual desire, fewer morning erections, and erectile dysfunction.
Even those are not proof. In that study, 25% to 35% of men with normal testosterone had these sexual symptoms too. Just 2.1% of the men had both the sexual symptoms and low testosterone. That figure was 0.6% for men in their 50s and 5.1% for men in their 70s. The combination was 13 times as common in men with obesity as in men at a normal weight.
Other signs raise more suspicion:
- Breast tenderness or enlargement
- Hot flashes or sweats
- Loss of underarm or pubic hair
- Infertility or a low sperm count
- Low bone density, or a fracture after a minor fall
How low testosterone is diagnosed
A diagnosis takes two things together: symptoms, and testosterone that is clearly and consistently low. The Endocrine Society recommends against routinely screening men in the general population, so testing usually starts with symptoms.
The blood draw has rules, because testosterone shifts through the day and from day to day.
- Morning. In one study, men aged 30 to 40 had levels 20% to 25% lower at 4 p.m. than at 8 a.m. At age 70 the gap was about 10%.
- Fasting. Food and glucose can lower the reading.
- Twice. About 30% of men whose first result is low have a normal result on repeat. Guidelines call for two tests on separate mornings.
- When you are well. Illness and some medications, such as opioids, can suppress testosterone for a time. Testing waits until you have recovered.
One low number is not a diagnosis. A single reading can be low because of the time of day, a recent meal, or a recent illness. The FDA-approved label for a testosterone gel (AndroGel 1.62%) tells prescribers to confirm low morning levels on at least two separate days first.
What counts as low? The American Urological Association uses a total testosterone below 300 ng/dL. The Endocrine Society uses the lower limit of a standardized range, 264 to 916 ng/dL, drawn from healthy, nonobese men aged 19 to 39. A result of 280 is low by one standard and normal by the other. That is why we never read the number alone.
What the rest of the panel shows
Total testosterone is the starting point, but most of it travels bound to proteins, mainly SHBG (sex hormone-binding globulin) and albumin. Only 2% to 4% circulates free.
SHBG changes the picture. Obesity and type 2 diabetes lower SHBG. That can pull total testosterone below the normal range while free testosterone may stay normal. Aging raises SHBG, so an older man's total can look fine while his free testosterone is low. The Endocrine Society calls for a free testosterone when the total is borderline or SHBG is likely to be off.
LH and FSH, the pituitary hormones that signal the testicles, show where the problem starts.
- High LH and FSH with low testosterone point to the testicles. This is called primary hypogonadism.
- Low or normal LH and FSH point to the pituitary or hypothalamus, called secondary hypogonadism. Next steps include a prolactin level, iron studies, and sometimes pituitary imaging.
A secondary pattern can uncover a pituitary problem that needs its own care. It is also the pattern seen with potentially reversible causes: obesity, other illness, and medications such as opioid pain medicines or corticosteroids.
When treatment is indicated, and when it isn't
The Endocrine Society recommends testosterone therapy for men who have both symptoms and confirmed low levels, to correct the symptoms of deficiency. For men 65 and older it is more cautious, suggesting an individual decision after a discussion of risks and benefits. Before starting, the American Urological Association calls for a blood count and, in men over 40, a PSA (prostate-specific antigen) test.
FDA status matters too. The FDA says testosterone is approved only for men whose low levels come with an associated medical condition. Examples include disorders of the testicles or pituitary. Product labels state that safety and efficacy in age-related low testosterone have not been established. The FDA kept that language in 2025. Compounded testosterone preparations are not FDA-approved products.
Trial results help set expectations. The Testosterone Trials enrolled 788 men aged 65 and older with clearly low levels. They used testosterone gel or a placebo for a year. Testosterone improved sexual desire, sexual activity, and erectile function. Mood improved slightly. Energy and thinking did not improve.
The Endocrine Society recommends against testosterone in several situations, including:
- Planning to father a child in the near term, because testosterone can suppress sperm production
- Breast or prostate cancer, or an elevated PSA that has not been evaluated
- A high red blood cell count (hematocrit)
- Untreated severe sleep apnea or uncontrolled heart failure
- A heart attack or stroke within the past six months
A normal level, or a single low one, is not a reason to treat. The cause deserves attention too. In men with obesity, a diet producing a 9.8% weight loss was linked to an average rise in total testosterone of 83 ng/dL. The American Urological Association advises lifestyle counseling for every man with low testosterone.
On treatment, monitoring continues. Testosterone can raise red blood cell counts and blood pressure, and in 2025 the FDA extended blood pressure warnings to all testosterone products. The same update reported that the TRAVERSE trial found no increase in adverse cardiovascular outcomes in men treated for low testosterone. The trial was not entirely reassuring. Heart rhythm problems needing treatment (5.2% versus 3.3%) and acute kidney injury (2.3% versus 1.5%) were more common with testosterone.
How to get an accurate test
- Book the draw for early morning, ideally between 7 and 10 a.m., and fast beforehand unless you have been told not to.
- Wait until any illness has passed.
- Bring your medication list, including pain medicines and corticosteroids.
- Tell us if you plan to have children; there are other approaches we can discuss.
- Expect a second test before any decision.
At Reset You MD, we start with your symptoms and history, then order morning labs. The panel includes total and free testosterone with SHBG, plus other markers your history calls for. If treatment makes sense, the dose is individualized and we recheck labs along the way.
The bottom line
Symptoms start the conversation. They don't finish it. Low testosterone is diagnosed when symptoms and two properly timed morning tests agree. If this sounds like you, book a complimentary consultation. We'll review your history, recommend the right labs, and tell you plainly whether treatment or another next step fits.
Sources
- Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 2018;103:1715-1744.
- Mulhall JP, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline (2018; validity confirmed 2024). American Urological Association.
- Grossmann M, Jayasena CN, Anawalt BD. Approach to the Patient: The Evaluation and Management of Men ≥50 Years With Low Serum Testosterone Concentration. J Clin Endocrinol Metab 2023;108:e871-e884.
- Brambilla DJ, et al. The Effect of Diurnal Variation on Clinical Measurement of Serum Testosterone and Other Sex Hormone Levels in Men. J Clin Endocrinol Metab 2009;94:907-913.
- Snyder PJ, et al. Lessons From the Testosterone Trials. Endocr Rev 2018;39:369-386.
- U.S. FDA: FDA issues class-wide labeling changes for testosterone products, February 28, 2025
- ANDROGEL (testosterone gel) 1.62% prescribing information, ASCEND Therapeutics U.S., revised October 2025 (DailyMed, U.S. National Library of Medicine)
- U.S. FDA: Compounding and the FDA: Questions and Answers
Website content is for general education and does not replace individualized medical advice, diagnosis, or treatment. Individual results vary. This article is general education from a Florida physician and does not create a doctor–patient relationship; talk with your own clinician about your situation.