Before Testosterone Replacement Therapy, Look Under the Hood.
Updated: 4 days ago
Why low testosterone is often a symptom—not the whole story.
Created by Chris Caffrey, ACNP, PMHNP, Functional Medicine-trained
July 12th 2026
Key Takeaways:
Low testosterone is often a signal, not the whole problem. Sleep, body fat, metabolic health, stress, medications, and lifestyle can all influence testosterone levels.
TRT should be based on symptoms, labs, and the full clinical picture. A low number alone is not enough to justify treatment.
When appropriately prescribed, TRT can meaningfully improve quality of life. Benefits may include better libido, energy, strength, muscle mass, body composition, and overall well-being.
TRT requires ongoing monitoring. Testosterone levels, hematocrit, blood pressure, prostate considerations, cardiovascular risk, fertility goals, symptoms, and side effects all matter.
TRT works best as part of a broader health strategy. Hormone therapy cannot replace good sleep, resistance training, adequate protein, metabolic health, and other fundamentals.
Most men do not wake up one morning and suddenly stop feeling like themselves. The change is usually gradual. Workouts that once left you energized now take longer to recover from. The weight around your waist becomes more stubborn, motivation starts slipping, libido changes, and the energy you once took for granted is not quite there anymore.
Eventually, someone mentions testosterone.
A quick internet search can make the answer seem obvious. Within minutes, social media has diagnosed you, recommended three supplements, prescribed testosterone, and promised to return you to the man you were at 25.
Unfortunately, the human body has never been particularly interested in simple stories.
Testosterone absolutely matters. But a low testosterone level can represent two very different things: sometimes testosterone deficiency is the problem, and sometimes it is more like a check-engine light telling us that something else deserves attention.
Understanding that difference is where good medicine begins.
Does Any of This Sound Familiar?
Men with testosterone deficiency may experience:
Lower libido or fewer spontaneous erections
Difficulty maintaining muscle or strength
Increased abdominal fat
Poorer exercise recovery
Fatigue or reduced stamina
Lower motivation or mood
Difficulty concentrating or feeling mentally sharp
A general sense of simply not feeling like themselves
The frustrating part is that many of these symptoms can also occur with poor sleep, sleep apnea, thyroid problems, depression, chronic stress, obesity, insulin resistance, medication effects, nutritional deficiencies, and other medical conditions.
That is why testosterone deficiency should not be diagnosed from symptoms alone. Current guidelines recommend combining compatible symptoms with consistently low testosterone measurements, generally confirmed with repeat morning testing.[1,2]
What could improvement actually look like?
For a man with true testosterone deficiency, successful treatment may mean improved sexual function, easier maintenance of lean muscle, stronger bones, improved anemia in selected patients, and a better overall sense of well-being. Some men describe it much more simply: they begin to feel like themselves again.[1,4]
That does not mean testosterone is a cure for every tired man over 40. Fatigue and brain fog are especially nonspecific symptoms, and TRT will not necessarily fix them if testosterone was never the real problem.
The goal is not to create the highest testosterone number possible. The goal is to understand what is happening and help you function and feel better while protecting your long-term health.
How I Approach Testosterone at Flexup Wellness
Before deciding whether testosterone belongs in your treatment plan, I want to understand why the testosterone is low in the first place.
That begins with the person, not the prescription.
During the initial consultation, we look at your symptoms, previous laboratory results, medications, sleep, nutrition, exercise, body composition, metabolic health, medical history, stress, and long-term goals. Fertility is also important because testosterone treatment can significantly affect sperm production.
Laboratory evaluation may include total testosterone, free testosterone, SHBG, LH, FSH, prolactin when indicated, a blood count, thyroid testing, metabolic markers, and prostate assessment when appropriate.
That may sound like alphabet soup, but each test can help answer a different question.
For example, LH and FSH are signals produced by the brain and pituitary gland that tell the testicles to make testosterone and sperm. Looking at those hormones can help distinguish whether low testosterone is primarily coming from the testicles themselves or whether the signal from the brain is inadequate.[1]
The goal is not to order every laboratory test available. It is to order the right tests for the right person.
If testosterone replacement turns out to be appropriate, ongoing TRT management through Flexup Wellness is $129 per month after the initial consultation, with continued clinical follow-up, laboratory monitoring, and individualized dose adjustments with supplies.
Prescribing testosterone is the easy part. Doing it properly is the important part.
Testosterone as the Check-Engine Light
Imagine driving home and seeing the check-engine light appear.
That little amber light tells you something deserves attention, but it does not tell you exactly what happened. Maybe it is a loose gas cap. Maybe it is a failing sensor. Maybe your engine has chosen that particular Tuesday to begin negotiating its retirement.
Low testosterone can work the same way.
Sometimes the testicles simply are not producing enough testosterone. Other times, lower testosterone may occur alongside excess body fat, untreated sleep apnea, poor sleep, certain medications, metabolic disease, significant illness, or problems involving the pituitary gland.
This is why I am less interested in asking:
“How do we raise your testosterone?”
and more interested in asking:
“Why did your testosterone become low?”
Those questions sound similar, but they can lead to very different treatment plans.
Testosterone Does Not Work in Isolation
Hormones are less like independent contractors and more like a very active group chat.
Your brain, pituitary gland, testicles, thyroid, liver, fat tissue, muscles, and other organs are constantly communicating with one another. Testosterone is one important voice in that conversation, but it is not the entire conversation.
Take body composition. Excess visceral fat, the fat stored deeper around the abdominal organs, is metabolically active. Obesity is associated with lower testosterone levels, while lower testosterone can make maintaining muscle and improving body composition more difficult.[1,2]
Sleep matters as well. A man sleeping five hours per night or living with untreated sleep apnea may experience fatigue, poor recovery, difficulty concentrating, metabolic dysfunction, and sexual symptoms that overlap considerably with testosterone deficiency.
Certain medications can also suppress testosterone production, including opioids and glucocorticoids. Occasionally the problem originates in the pituitary gland, which is why the hormonal signals upstream from testosterone matter.
This is where looking at the whole picture becomes useful. Sometimes improving weight, sleep, metabolic health, exercise, or another underlying issue improves the hormonal environment enough that testosterone replacement is not necessary.
Other times, we correct those issues and testosterone remains genuinely deficient.
That is when TRT becomes a very different conversation.
When Testosterone Really Is the Answer
Some men truly have hypogonadism, meaning the body cannot produce adequate testosterone to meet normal physiologic needs.
This may occur because of testicular dysfunction, pituitary disease, previous chemotherapy, injury, genetic conditions, or other causes. In these situations, testosterone replacement is not a shortcut around healthy living. It is replacing something the body is no longer producing adequately.
When prescribed appropriately, TRT can improve sexual desire and erectile function and can favorably affect lean body mass, bone density, and anemia in selected men.[1,4]
What it cannot do is replace the fundamentals.
Testosterone will not magically cancel out chronic sleep deprivation, years of inactivity, excessive alcohol intake, poor nutrition, or uncontrolled metabolic disease. If those things are working against you, they still deserve attention.
Think of TRT as one tool in the toolbox, not the entire construction crew.
Is TRT Safe?
This is usually where the conversation gets more serious, and it should.
Testosterone can be used safely in appropriately selected men, but it requires thoughtful screening and ongoing monitoring. Like any meaningful medical therapy, it has potential benefits and potential risks.
Cardiovascular health
One of the most important recent studies was the TRAVERSE trial, which followed more than 5,000 men with hypogonadism who either had cardiovascular disease or were at increased cardiovascular risk.
The study found that testosterone therapy did not increase the overall rate of major cardiovascular events compared with placebo.[3]
That was reassuring, but it does not mean testosterone is risk-free. Some adverse events, including atrial fibrillation and pulmonary embolism, occurred more frequently in the testosterone group. Testosterone products also require attention to blood pressure and other cardiovascular risk factors.
The lesson is not that monitoring is unnecessary. The lesson is that good monitoring is part of good TRT.
Hematocrit
Testosterone stimulates red blood cell production. For some men with anemia, that can be beneficial.
Sometimes, however, hematocrit rises too high.
Hematocrit is simply the percentage of your blood made up of red blood cells. If that number becomes excessive, treatment may need to be adjusted, which is why periodic blood counts are an important part of ongoing therapy.[1,2]
Prostate health
For decades, men were told that testosterone replacement would inevitably fuel prostate cancer. The current evidence is considerably more nuanced.
Available data have not demonstrated that appropriately prescribed testosterone therapy causes prostate cancer in carefully selected men, but prostate health still deserves appropriate evaluation and monitoring.[1,2]
That is a much more useful position than either extreme: “testosterone causes prostate cancer” or “there is absolutely nothing to worry about.”
Medicine is rarely that binary.
Fertility: The Conversation Men Need Before Starting TRT
This is one of the most important things to understand before beginning treatment.
External testosterone tells the brain that plenty of testosterone is already present. The brain responds by reducing LH and FSH signaling to the testicles, and sperm production can fall dramatically.
In plain English:
TRT can significantly reduce fertility.
Men currently trying to conceive should generally not receive traditional exogenous testosterone therapy, and men who may want children in the future should discuss that possibility before treatment begins.[1,2]
There are alternative approaches that may be more appropriate when maintaining fertility is important.
This is one of those conversations that is considerably easier to have before the first prescription than six months afterward.
What Is the Best Type of Testosterone?
There is no universally best option.
Injectable testosterone remains widely used because it is effective, relatively affordable, and allows precise adjustment of the dose. Many men who initially dislike the idea of injections find that small injections at home quickly become routine.
Other options include topical gels and FDA-approved oral testosterone undecanoate products. Modern oral testosterone is different from older oral anabolic steroids associated with significant liver toxicity, although oral therapy has its own considerations, including cost, dosing frequency, absorption, and blood-pressure monitoring.
The best treatment is not whichever version is receiving the most attention online.
It is the one that fits your physiology, lifestyle, risks, preferences, and goals.
The Laboratory Number Is Not the Finish Line
One of the easiest mistakes in hormone medicine is becoming obsessed with the testosterone number.
A laboratory value is useful, but it is not the patient.
If your testosterone rises beautifully on paper while you still feel miserable, we need to ask why. The American Urological Association recommends reconsidering ongoing therapy when testosterone levels normalize but symptoms do not meaningfully improve.[2]
That principle matters to me.
I am not interested in treating laboratory reports. I am interested in helping people function better, feel better, and understand what is happening inside their bodies.
Sometimes testosterone really is the missing piece.
Sometimes low testosterone is the check-engine light pointing toward something else.
And sometimes both are true.
The challenge is not deciding whether testosterone is good or bad. The challenge is figuring out what your body is trying to tell us.
That is how I approach TRT at Flexup Wellness.
The goal was never simply to turn off the warning light.
The goal is to take care of the engine.
If you have been wondering whether low testosterone could be contributing to how you feel, the first step is not automatically starting testosterone. It is taking the time to understand the symptoms, confirm the laboratory findings, identify potential causes, and determine whether TRT actually belongs in the plan.
References
Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism. 2018;103(5):1715–1744.
Mulhall JP, Trost LW, Brannigan RE, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline. Journal of Urology. 2018;200(2):423–432. Updated guidance available through the American Urological Association.
Lincoff AM, Bhasin S, Flevaris P, et al. Cardiovascular Safety of Testosterone-Replacement Therapy. New England Journal of Medicine. 2023;389:107–117.
Snyder PJ, Bhasin S, Cunningham GR, et al. Effects of Testosterone Treatment in Older Men. New England Journal of Medicine. 2016;374:611–624.
U.S. Food and Drug Administration. Class-Wide Labeling Changes for Testosterone Products. 2025.
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