Getting a prescription for testosterone replacement therapy (TRT) requires two things: blood work showing low testosterone and symptoms that match. A doctor won’t prescribe based on one or the other alone. The standard diagnostic threshold most clinicians use is a total testosterone level below 300 ng/dL, confirmed on at least two separate morning blood draws, combined with a clinical picture that fits. The process from first appointment to filling a prescription typically takes a few weeks, though it can stretch longer if your results fall in a gray zone or additional testing is needed.
What Doctors Actually Measure
The first step is a blood test for total testosterone. The American Urological Association recommends using 300 ng/dL as the cutoff below which a diagnosis of low testosterone is supported, a figure drawn from evaluating randomized controlled trials where the median baseline testosterone of enrolled men was around 250 ng/dL.1The Journal of Urology. Evaluation and Management of Testosterone Deficiency: AUA Guideline Other medical societies worldwide use thresholds ranging from 230 to 350 ng/dL, so there is no single universally agreed-upon number. But in most American clinics, 300 ng/dL is the line your doctor will reference.
Your doctor will want at least two low readings before moving forward. The standard recommendation calls for early-morning fasting blood samples on two separate days, since testosterone peaks in the morning and can fluctuate day to day.2PubMed. Optimizing Diagnostic Accuracy and Treatment Decisions in Men With Testosterone Deficiency One interesting wrinkle: a study comparing fasting and non-fasting testosterone levels found no significant difference between the two, raising questions about whether fasting is strictly necessary.3PubMed. Is a fasting testosterone level really necessary for the determination of androgen status in men? Still, most doctors will ask you to fast and come in early as a default, partly because the guidelines haven’t been updated to reflect that finding and partly because consistency between draws matters.
If your total testosterone is borderline, hovering near that 300 line, your doctor may order a free testosterone test. Only about 2% of testosterone in your blood is “free,” meaning it’s not bound to proteins and is available for your body to use. Some men have normal total testosterone but low free testosterone, or vice versa, because a protein called sex hormone-binding globulin (SHBG) can skew the relationship between the two numbers. Measuring free testosterone in these borderline cases helps avoid both missed diagnoses and unnecessary prescriptions.4PubMed Central. Role of sex hormone-binding globulin in the free hormone hypothesis and the relevance of free testosterone in androgen physiology Conditions like obesity, liver disease, and aging can all shift SHBG levels, making free testosterone particularly useful for men whose total testosterone sits right at the edge.5PubMed. Accurate measurement of total and free testosterone levels for the diagnosis of androgen disorders
Symptoms Matter as Much as Numbers
A low number alone doesn’t guarantee a prescription. Your doctor needs to document that you’re experiencing symptoms consistent with testosterone deficiency. The classic ones include low sex drive, erectile difficulty, fatigue, loss of muscle mass, increased body fat, depressed mood, and difficulty concentrating. Some clinicians use screening questionnaires like the ADAM (Androgen Deficiency in the Aging Male) to systematically check for these symptoms. The ADAM questionnaire picks up most men who turn out to have low testosterone, with sensitivity reported at 88% or higher, but it also flags a lot of men who don’t, with specificity as low as 30%.6PubMed. Comparison of screening questionnaires for the diagnosis of hypogonadism That means the questionnaire is better at ruling out testosterone deficiency than confirming it, which is why the blood test is indispensable.
In practice, some doctors won’t use a formal questionnaire at all. They’ll simply ask about your symptoms during the consultation. What matters is that you’re honest and specific. “I’m tired all the time” is vague enough to come from a hundred causes. “My sex drive has dropped noticeably over the past year, I can’t maintain erections, and I’ve gained weight despite no change in diet” paints a clearer picture. The more specific you are, the easier it is for your doctor to connect the dots between your symptoms and your lab values.
Finding the Cause
Once low testosterone is confirmed, your doctor will want to figure out why it’s low. This step determines both your diagnosis and, in some cases, your treatment options. The distinction comes down to where in the hormonal chain the problem sits. In primary hypogonadism, the testes themselves aren’t producing enough testosterone, and your brain’s signaling hormones (LH and FSH) are elevated because they’re trying to compensate. In secondary hypogonadism, the problem is in the brain’s pituitary gland or hypothalamus, so LH and FSH are low or inappropriately normal.7The Journal of Clinical Endocrinology & Metabolism. Characteristics of Secondary, Primary, and Compensated Hypogonadism in Aging Men: Evidence from the European Male Ageing Study
Your doctor will order LH and FSH levels alongside your testosterone to make this distinction.2PubMed. Optimizing Diagnostic Accuracy and Treatment Decisions in Men With Testosterone Deficiency They may also check prolactin, thyroid function, iron levels, and sometimes order imaging of the pituitary gland if secondary hypogonadism is suspected, because a benign pituitary tumor is one treatable cause that would change your management entirely. Conditions like obstructive sleep apnea can also drive testosterone down, and treating the sleep apnea sometimes improves levels on its own. Doctors are advised to screen for sleep apnea symptoms before starting TRT, since testosterone therapy can worsen untreated severe cases.8PubMed Central. Obstructive Sleep Apnea and Testosterone Deficiency
The Gray Zone of Age-Related Low Testosterone
Here’s where the process gets more complicated, and where you may encounter resistance. TRT has been approved in the U.S. since the 1950s for men with “classical” hypogonadism, meaning there’s a recognized disease of the testes, pituitary, or hypothalamus causing the deficiency.9PubMed Central. Testosterone Therapy for the Treatment of Age-Related Hypogonadism: Risks with Uncertain Benefits The more contentious group is older men, or men with obesity and other health conditions, whose testosterone has drifted below 300 ng/dL without a clear disease causing it. No testosterone product is FDA-approved for this “age-related” decline, and professional societies disagree on whether these men should be treated.
The Endocrine Society’s guidelines allow for testosterone therapy in these men as a shared decision between doctor and patient, classifying age-related decline as a form of organic hypogonadism and obesity-related decline as functional hypogonadism. An Australian position statement took a harder line, recommending against testosterone therapy for men whose low levels are explained by aging or comorbidities alone.10PubMed. Clinical practice update on testosterone therapy for male hypogonadism: Contrasting perspectives to optimize care In practice, many American doctors will prescribe TRT to symptomatic men with confirmed low testosterone regardless of whether a classical cause is identified, but some will push you to address weight, sleep, and other reversible factors first.
Lifestyle Changes Your Doctor May Recommend First
Before writing a prescription, some doctors will suggest lifestyle interventions, particularly if your testosterone is borderline rather than deeply low or if you have modifiable risk factors like obesity. Weight loss, regular exercise, better sleep, and stress reduction can all raise testosterone levels.11Sexual Medicine Reviews. Alternatives to Testosterone Therapy: A Review The connection between obesity and low testosterone is especially strong and bidirectional: excess body fat drives testosterone down, and low testosterone promotes fat gain. For some men, losing a meaningful amount of weight can push testosterone back into the normal range without medication.
This isn’t your doctor stalling. Guidelines from multiple medical societies recommend considering these alternatives before jumping to TRT, especially since the therapy is typically lifelong once started. If your levels are well below 300 ng/dL and you have pronounced symptoms, most doctors won’t ask you to lose 30 pounds before offering treatment. But if you’re at 280 ng/dL with a BMI of 35, don’t be surprised if your doctor wants to see what three to six months of lifestyle changes can do.
Choosing a Treatment Formulation
Once your doctor decides to prescribe, you’ll discuss which form of testosterone to use. The main options are topical gels, intramuscular injections, subcutaneous pellets, patches, and nasal gels. Each has trade-offs in convenience, cost, and side effect profile.
Injectable testosterone (usually cypionate or enanthate) produces the highest testosterone levels but also carries the highest rate of a side effect called erythrocytosis, where red blood cell counts climb too high. In one comparative study, about two-thirds of men on injections developed a hematocrit above 50%, compared with roughly 13% on gels and 35% on pellets.12PubMed Central. Comparison of the Effects of Testosterone Gels, Injections, and Pellets on Serum Hormones, Erythrocytosis, Lipids, and Prostate-Specific Antigen The peaks and valleys of injection cycles contribute to this. Gels deliver a steadier daily dose but require careful application to avoid transferring testosterone to partners or children through skin contact. Pellets, implanted under the skin every few months, offer convenience but require a minor in-office procedure for each dose.
Your doctor’s recommendation will depend on your lifestyle, your tolerance for injections, your insurance coverage, and your baseline hematocrit. There’s no single “best” formulation. Many men start on gels for their ease and steady levels, then switch to injections for cost or preference reasons.
What Happens After You Start
TRT isn’t a quick fix. Different benefits show up on different timelines. Improvements in sex drive tend to appear within about three weeks and plateau around six weeks. Mood improvements begin within a few weeks but can take four to seven months to reach their maximum. Changes in body composition, like gaining lean mass and losing fat, take three to four months to become noticeable and continue for six months to a year. Effects on bone density don’t show up for at least six months and continue for years.13PubMed Central. Onset of effects of testosterone treatment and time span until maximum effects are achieved If you’re expecting to feel dramatically different within days, recalibrate. Some men notice energy and mood shifts early, but the full picture takes months to develop.
Your doctor will schedule follow-up blood work to confirm that your levels have reached the target range. The timing depends on your formulation. For gels, levels are typically checked two to four weeks after starting, with the blood draw timed two to eight hours after application. For short-acting injections, assessment happens after three to four injection cycles. For pellets, an initial check at two to four weeks is followed by another at ten to twelve weeks.14PubMed Central. An Individualized Approach to Managing Testosterone Therapy in the Primary Care Setting One study of men on testosterone gel found that while 70% had adequate levels two hours after application, only about 37% maintained them by the following morning, which is why timing the blood draw matters and why dose adjustments are common early on.15PubMed. Monitoring testosterone replacement therapy with transdermal gel: when and how?
Beyond testosterone levels, your doctor will monitor your hematocrit (red blood cell concentration), PSA (prostate-specific antigen), and lipid panel at regular intervals. If your hematocrit climbs above roughly 54%, guidelines suggest either reducing your testosterone dose or considering phlebotomy, though there’s growing debate about whether repeated phlebotomy is actually helpful. Removing blood lowers hematocrit in the short term but can deplete iron stores and paradoxically shift oxygen-delivery dynamics in ways that may not reduce clotting risk as intended.16Endocrine Connections. Testosterone therapy-induced erythrocytosis: can phlebotomy be justified?
Cardiovascular and Prostate Safety
For years, the biggest cloud hanging over TRT was the question of heart risk. The TRAVERSE trial, the largest randomized controlled trial ever conducted on testosterone therapy, largely put this concern to rest. In over 5,000 men with hypogonadism and either existing cardiovascular disease or high risk for it, major cardiac events occurred at about the same rate whether men received testosterone or placebo.17PubMed. Cardiovascular Safety of Testosterone-Replacement Therapy A meta-analysis pooling 30 randomized trials echoed this, finding no increased risk of cardiovascular events, stroke, heart attack, or death with TRT compared to placebo.18PubMed. Association between testosterone replacement therapy and cardiovascular outcomes: A meta-analysis of 30 randomized controlled trials The TRAVERSE trial did flag slightly higher rates of atrial fibrillation, acute kidney injury, and pulmonary embolism in the testosterone group, so monitoring remains important even though the headline cardiovascular concern has faded.19PubMed Central. Long Term Cardiovascular Safety of Testosterone Therapy: A Review of the TRAVERSE Study
Prostate cancer has been the other major worry. Data from the TRAVERSE trial showed no significant difference in prostate cancer rates between men on testosterone and those on placebo over several years of follow-up. PSA levels rose modestly with treatment, but the increase plateaued by about twelve months, and prostate cancer incidence, including high-grade cases, was essentially the same in both groups.20JAMA Network Open. Prostate Safety Events During Testosterone Replacement Therapy in Men With Hypogonadism: A Randomized Clinical Trial A separate meta-analysis of the broader literature also found no link between TRT and increased prostate cancer risk or clinically meaningful PSA elevation.21PubMed. Endogenous and exogenous testosterone and the risk of prostate cancer and increased prostate-specific antigen (PSA) level: a meta-analysis Your doctor will still monitor PSA, but the old fear that testosterone “feeds” prostate cancer has not held up in controlled studies.
Fertility Is a Separate Conversation
If you’re planning to have children, bring this up before starting TRT. Exogenous testosterone tells your brain that plenty of hormone is available, which shuts down the signals (LH and FSH) that drive sperm production. Many men on TRT see their sperm count drop to zero or near-zero. This effect is usually reversible, but recovery isn’t guaranteed and can take months to over a year.
For men who need both testosterone therapy and preserved fertility, doctors sometimes prescribe alternatives like clomiphene citrate or human chorionic gonadotropin (hCG), which stimulate the body’s own testosterone production without suppressing sperm. For men who’ve already been on TRT and want to restore fertility, a combination of hCG and FSH can help. In one study of 77 men with a history of testosterone use, about 74% showed improvement in sperm concentration after this kind of recovery protocol, whether or not they continued testosterone therapy alongside it.22PubMed. Optimal restoration of spermatogenesis after testosterone therapy using human chorionic gonadotropin and follicle-stimulating hormone The takeaway: fertility is manageable, but you need to plan for it upfront rather than discovering the problem later.
Telemedicine and Direct-to-Consumer Options
The rise of telehealth has made it easier to access TRT without visiting a specialist in person. Telemedicine platforms can provide guideline-concordant management and may be particularly useful for men who feel uncomfortable discussing sexual health symptoms face to face, or who live far from an endocrinologist or urologist.23PubMed Central. Testosterone replacement therapy in the era of telemedicine You’ll typically complete an online consultation, get a lab order for local blood work, and have a video follow-up to review results.
There are real limitations, though. A telemedicine doctor can’t perform a physical exam, including a digital rectal exam for prostate assessment or a testicular exam that might reveal a varicocele or other structural issue. Because all forms of testosterone are classified as Schedule III controlled substances in the United States, prescribing them remotely carries additional regulatory requirements that vary by state.23PubMed Central. Testosterone replacement therapy in the era of telemedicine Some direct-to-consumer platforms have drawn criticism for prescribing testosterone with less thorough diagnostic workups than guidelines recommend. If you go the telemedicine route, look for platforms that require two confirmed low testosterone readings, evaluate your symptoms formally, check LH and FSH, and schedule regular follow-up labs. A platform that sends you testosterone after a single questionnaire and one blood draw is cutting corners.
Prescription Drug Monitoring and Controlled Substance Rules
Because testosterone is a Schedule III controlled substance, your prescription will be tracked. Many states have implemented prescription drug monitoring programs (PDMPs) that require providers to check a database before prescribing controlled medications.24Sexual Medicine. Effect of Prescription Drug Monitoring Programs on Testosterone Prescriptions This adds a minor step to the process but shouldn’t affect legitimate prescriptions. Your pharmacist may need to order the specific formulation, since not all pharmacies stock every testosterone preparation. Refills typically require a new prescription or a refill authorization, and your doctor may require updated blood work before authorizing refills at certain intervals.
If you travel frequently, keep in mind that carrying injectable testosterone across state lines or internationally may require documentation. A copy of your prescription and a letter from your doctor can prevent problems at airports or border crossings. Some countries have stricter regulations around anabolic steroids than the U.S., so check before traveling abroad with your medication.
When Your Doctor Says No
Not every man who wants TRT will get it, and there are legitimate medical reasons a doctor might decline. Active or recently treated prostate or breast cancer, untreated severe sleep apnea, an elevated hematocrit before treatment even starts, uncontrolled heart failure, and a desire for near-term fertility are all situations where most guidelines recommend against starting testosterone. A very high red blood cell count at baseline is a red flag because TRT will push it higher.
If your testosterone is above 300 ng/dL but you have symptoms you believe are related to low testosterone, your doctor may not diagnose you with hypogonadism at all. Some men in this situation seek a second opinion, particularly from a urologist or endocrinologist who may interpret borderline cases differently than a primary care physician. The free testosterone test can sometimes clarify the picture in these borderline situations, as we discussed earlier. If your total testosterone is 320 ng/dL but your free testosterone is genuinely low, some specialists will consider treatment.25PubMed Central. Testosterone Deficiency – Establishing A Biochemical Diagnosis
The most productive approach is to go into the appointment prepared: know your symptoms, be ready to discuss your medical history honestly, and understand that the process involves multiple blood draws and possibly some waiting. Doctors who are cautious about TRT aren’t trying to gatekeep for its own sake. They’re following a diagnostic framework designed to make sure the treatment will help rather than expose you to risk for a condition you don’t actually have.