There is a significant gap between testosterone replacement therapy as it exists in the clinical literature and testosterone replacement therapy as it is commonly practiced.
The clinical literature describes a structured process: careful baseline evaluation, standardized dosing initiation, defined monitoring intervals, reassessment of both lab values and symptoms, and ongoing attention to the conditions that testosterone therapy can affect — hematocrit, estradiol, PSA, cardiovascular status. The guidelines from the Endocrine Society, the British Society for Sexual Medicine, and the American Urological Association describe this process in considerable detail.
What patients often encounter instead is a lab test, a prescription, and a refill with minimal follow-up.
Getting TRT right is not complicated. It requires doing the same things consistently, at the right intervals, and interpreting the results in the context of the patient rather than the reference range. This post describes what that looks like.
The Baseline Evaluation
Before initiating testosterone therapy, a proper baseline establishes several things simultaneously. It confirms the diagnosis, identifies the likely etiology, rules out contraindications, and creates a reference point against which treatment response can be measured.
Confirming the diagnosis. The Endocrine Society recommends confirming low total testosterone on at least two separate morning fasting measurements before initiating treatment. Testosterone is diurnal — levels are highest in the morning and fall through the day. A single afternoon measurement is not a reliable baseline. Two morning measurements on separate days, both below the clinical threshold (typically 300 ng/dL or the lab’s lower reference limit), with consistent symptoms, is the appropriate confirmation standard.
Total versus free testosterone. Total testosterone includes both bound (to SHBG and albumin) and free (unbound) fractions. Only free testosterone enters cells and exerts hormonal effects. In men with elevated SHBG — which is common with aging, liver disease, and thyroid disorders — total testosterone can be at the lower end of normal while free testosterone is clinically low. Men with low SHBG (metabolic syndrome, obesity) may have total testosterone in the normal range with normal free testosterone. Both values matter and should be assessed together at baseline.
LH and FSH. Measuring LH and FSH at baseline distinguishes primary from secondary (central) hypogonadism and has treatment implications. Low testosterone with elevated LH and FSH suggests primary testicular failure. Low testosterone with low or inappropriately normal LH and FSH suggests a secondary (hypothalamic or pituitary) cause that may warrant imaging of the pituitary before initiating testosterone replacement.
PSA and digital rectal exam. Testosterone replacement is contraindicated in men with active prostate cancer. PSA is measured at baseline and monitored on treatment. The historical concern about testosterone causing prostate cancer has not been borne out by evidence — the saturation model suggests that prostate tissue androgen receptors are fully occupied at low testosterone levels and that supra-physiologic testosterone does not proportionately increase prostate cancer risk. But baseline PSA matters, and men with PSA above 4 ng/mL or with abnormal DRE should have urological evaluation before starting TRT.
Hematocrit. Testosterone stimulates erythropoiesis. Polycythemia is the most common dose-dependent side effect of testosterone therapy and is clinically significant because elevated hematocrit increases blood viscosity and thrombotic risk. Baseline hematocrit should be measured and men with hematocrit above 50% should not initiate TRT until the cause is investigated.
Estradiol. Testosterone is aromatized to estradiol. Excessive aromatization — particularly in men with elevated adipose tissue — can produce symptomatic estradiol elevation: gynecomastia, water retention, and mood changes. Baseline estradiol establishes the starting point for monitoring.
Metabolic panel, lipids, and consideration of sleep apnea. Because functional hypogonadism and organic hypogonadism often coexist in the same patient, a baseline metabolic assessment and sleep history are appropriate. Untreated severe sleep apnea significantly worsens on exogenous testosterone (erythropoiesis increases, and sleep apnea severity may worsen). Identifying and treating sleep apnea before or alongside TRT initiation is appropriate care.
The First 90 Days
Testosterone therapy does not produce effects overnight. The clinical literature suggests that different symptoms respond on different timescales.
Sexual function — libido and the frequency of sexual thoughts — typically begins to improve within 3 to 6 weeks. Erectile function may take longer, 3 to 6 months, and may be partially responsive in men where vascular or neurological factors contribute.
Energy, mood, and sense of wellbeing typically improve over 3 to 6 weeks. This is often the first effect men notice and is frequently the most motivating.
Body composition — reduced fat mass, increased lean mass — begins to change over 3 to 6 months and continues for up to a year. These changes are gradual and require consistent treatment and reasonable baseline activity.
Bone mineral density changes require 1 to 2 years of treatment to measure reliably by DEXA.
Understanding this timeline matters because men who start testosterone therapy expecting immediate transformation in all domains may discontinue prematurely if early effects are subtle.
The first follow-up lab check is typically at 6 to 8 weeks after initiating or adjusting therapy. At this point the goals are: confirming that testosterone levels are in the target range (generally mid-normal: 400 to 700 ng/dL for most men), checking hematocrit, and assessing symptom response.
The 6-Month Check-In Structure
The 6-month monitoring interval is the clinical standard for ongoing TRT management and maps directly to the rhythm of well-designed telehealth TRT programs.
At 6 months, the monitoring typically includes:
Total testosterone and free testosterone. The goal is mid-physiologic range. Levels above 700–900 ng/dL suggest the dose should be reduced. Levels below 300–350 ng/dL suggest inadequate dosing, poor adherence, or absorption issues with topical preparations.
Hematocrit. The clinically significant threshold is typically 54%. Above this level, dose reduction or a therapeutic phlebotomy may be warranted. Hematocrit tends to peak in the first 6 to 12 months of treatment and then stabilize.
PSA. Testosterone does not cause prostate cancer, but it may unmask occult prostate cancer by stimulating growth that was already occurring. A PSA rise of more than 1.4 ng/mL in any 12-month period, or absolute PSA above 4 ng/mL, warrants urological referral regardless of baseline.
Estradiol. Symptomatic estradiol elevation (gynecomastia, bloating, mood instability) is common enough that targeted monitoring is warranted, especially in men with obesity or metabolic syndrome who have higher baseline aromatase activity.
Symptom reassessment. Lab values are not the primary outcome. The primary outcome is how the patient feels. Standardized symptom questionnaires — the Aging Males’ Symptoms scale is widely used — provide a structured framework for tracking symptom trajectory.
Where Telehealth Has Changed Access
The most significant change the telehealth model has brought to TRT is access, not protocol.
Men who previously could not get a testosterone evaluation without a primary care physician referral to a urologist or endocrinologist — a process that could take months in many healthcare systems — can now initiate the evaluation process online, receive a home blood collection kit, complete labs without a clinic visit, and have a synchronous or asynchronous consultation with a licensed clinician.
The quality of this access varies considerably by platform. Platforms that follow the evaluation and monitoring protocols described in this post provide genuinely better care than many patients previously received. Platforms that initiate TRT from a single testosterone value without appropriate baseline work and without structured monitoring fall short of the standard.
The home blood collection kit — the Tasso device or similar at-home capillary blood collection — has been a meaningful practical enabler. Eliminating the requirement to visit a phlebotomy lab for every monitoring check removes a meaningful adherence barrier. Men who would not reliably make 6-month clinic appointments for blood draws will reliably activate a home kit.
The clinical essentials have not changed. What has changed is the infrastructure around them.
Next up: Series 10 finale — the full arc, from Berthold’s four roosters in 1849 to the transdermal spray of 2025. 175 years compressed into one post.
