Testosterone

Dosing from the Literature

Published for low testosterone: 75–100 mg a week by injection (Endocrine Society), or the label doses of gels and other forms. Not published: an approved dose above the normal range.

The rows below give each product's FDA label dose, the Endocrine Society guideline's injection doses (Bhasin et al., 2018), and what men's-health clinic protocols describe.

What It Is

Testosterone is the primary endogenous male sex hormone and the prototypical anabolic-androgenic steroid. In men, the Leydig cells of the testes make it, stimulated by the pituitary hormone LH (Mulhall et al., 2018). The Endocrine Society's harmonized normal range for total testosterone in healthy, nonobese men aged 19 to 39 is 264–916 ng/dL (Bhasin et al., 2018). Levels fall with age: in the Baltimore Longitudinal Study of Aging, about 20% of men over 60, 30% over 70 and 50% over 80 had total testosterone in the hypogonadal range (Harman et al., 2001).

Therapeutically, testosterone is supplied as a series of esterified derivatives (cypionate, enanthate, propionate, undecanoate) or as transdermal gels, pellets, and more recently subcutaneous autoinjectors. Esterification delays hydrolysis and extends the duration of action. The Depo-Testosterone label gives intramuscular testosterone cypionate a half-life of about 8 days, and a phase 2 study measured about 7 days (173 hours) after a 200 mg intramuscular dose of enanthate (Kaminetsky et al., 2015). The cypionate and enanthate labels dose them every 2 to 4 weeks (Depo-Testosterone and testosterone enanthate labels); the Endocrine Society guideline, weekly or every 2 weeks (Bhasin et al., 2018). The cypionate label warns against using it interchangeably with testosterone propionate, whose duration of action differs (Depo-Testosterone label).

Testosterone replacement therapy (TRT) is FDA-approved for the treatment of hypogonadism in men. It is the most-studied anabolic-androgenic steroid in human clinical populations, with a clinical evidence base spanning over 80 years and thousands of randomized controlled trials. The 2018 Endocrine Society Clinical Practice Guideline (Bhasin et al., J Clin Endocrinol Metab 2018; PMID 29562364) is the authoritative guidance document for US prescribing practice. The 2023 TRAVERSE trial (Lincoff et al., NEJM; PMID 37326322), enrolling 5,246 middle-aged and older men with hypogonadism and elevated cardiovascular risk, established that TRT does not increase major adverse cardiovascular events versus placebo — resolving two decades of cardiovascular-safety debate but also documenting an atrial fibrillation signal that informs modern risk-benefit conversations.

In the Kalios compound context, testosterone is included because it is the foundational reference point for male hormonal optimization protocols. Most peptide protocols in men — GH secretagogues, kisspeptin, PT-141, tesamorelin — either assume baseline testosterone is normal or are layered onto a TRT foundation. Understanding testosterone is therefore prerequisite to understanding most male-specific peptide protocols. TRT is a legitimate FDA-regulated prescription, is scheduled under DEA Schedule III, and requires medical supervision; it is fundamentally different from the gray-market research peptides that comprise most of this database.

Mechanism of Action

Testosterone is a steroid hormone whose main active metabolites are estradiol and dihydrotestosterone (DHT) (Xyosted label). In healthy men whose own hormones were suppressed, its effects on lean mass, muscle size and strength came from androgen action, while its effect on body fat came mainly through estradiol, and both shaped sexual function (Finkelstein et al., 2013; PMID 24024838). Understanding testosterone's mechanism requires understanding both its direct androgen effects and its metabolic downstream (DHT, estradiol).

• Androgen receptor (AR) activation — In many tissues testosterone's activity appears to depend on its reduction to DHT, which binds receptor proteins; the hormone-receptor complex moves to the nucleus and starts gene transcription (Depo-Testosterone label). The labels credit androgens with male sexual development and hair pattern, muscle and fat distribution, protein building and red-cell production (Depo-Testosterone label).
• 5α-reductase conversion to DHT — Two forms of 5α-reductase convert testosterone to DHT: type I mainly in the skin's sebaceous glands and the liver, type II mainly in the prostate, seminal vesicles, hair follicles and liver (Propecia label). On Xyosted, DHT ran at about 7% of testosterone (mean ratio 0.07) (Xyosted label). Balding scalp holds more DHT than hairy scalp; finasteride 1 mg, a type II inhibitor, lowered serum DHT by 65% within 24 hours, and testosterone rose about 15%, staying in the normal range (Propecia label).
• Aromatization to estradiol (E2) — More than 80% of circulating estradiol in men comes from aromatization of testosterone (Finkelstein et al., 2013; PMID 24024838). In men whose own hormones were suppressed, blocking estradiol with anastrozole raised body fat, and loss of estradiol contributed to falling sexual function (Finkelstein et al., 2013; PMID 24024838); the AUA guideline calls estradiol essential to bone density and advises against long use of aromatase inhibitors for that reason (Mulhall et al., 2018; PMID 29601923).
• Skeletal muscle protein synthesis — Androgens have been reported to increase protein building and decrease protein breakdown (Depo-Testosterone label). In 43 healthy men, 600 mg of testosterone enanthate a week for 10 weeks enlarged arm and leg muscles and raised strength even without exercise, and more with weight training (Bhasin et al., NEJM 1996; PMID 8637535); in men whose own testosterone was suppressed, lean mass and thigh muscle shrank on placebo or the lowest gel dose (Finkelstein et al., 2013; PMID 24024838).
• Erythropoiesis (hematocrit elevation) — The labels say androgens stimulate red-cell production (Depo-Testosterone label). In young and older men given graded weekly doses, hemoglobin and hematocrit rose with the dose, more in older men; changes in erythropoietin and soluble transferrin receptor levels did not differ across the dose groups, and the authors suggest the rise may be mediated by factors other than these (Coviello et al., 2008; PMID 18160461). The AUA guideline calls the rise the most frequent adverse event of testosterone therapy (Mulhall et al., 2018; PMID 29601923).
• HPG axis suppression — Testosterone given from outside inhibits the pituitary's LH by feedback, shutting down the body's own testosterone release, and at large doses its FSH, suppressing sperm production (Depo-Testosterone label); 200 mg of enanthate a week cut intratesticular testosterone by 94% within 3 weeks (Mulhall et al., 2018; PMID 29601923). hCG acts like LH on the testes' Leydig cells, and in one small study low-dose hCG given with testosterone kept intratesticular testosterone at baseline (Mulhall et al., 2018; PMID 29601923).
• Bone mineral density — Hypogonadism, like aging, brings reduced bone mass (Harman et al., 2001; PMID 11158037), and the AUA guideline lists bone density among what testosterone therapy may improve (Mulhall et al., 2018; PMID 29601923); in a review of treatment studies, effects on bone appeared after 6 months and continued for at least 3 years (Saad et al., 2011; PMID 21753068).
• CNS effects — In men 65 or older with low testosterone, a year of testosterone gel raised sexual desire and slightly improved mood, with no benefit in vitality (Snyder et al., 2016; PMID 26886521); the AUA guideline calls the evidence on cognitive function inconclusive (Mulhall et al., 2018; PMID 29601923).
• Cardiovascular effects — In 220 hypogonadal men with type 2 diabetes or metabolic syndrome, testosterone gel cut insulin resistance (HOMA-IR) by 15.2% at 6 months (Jones et al., 2011; PMID 21386088); the AUA guideline calls the evidence on diabetes measures and lipid profiles inconclusive (Mulhall et al., 2018; PMID 29601923). TRAVERSE found testosterone gel noninferior to placebo for major cardiac events in men with hypogonadism and heart disease or a high risk of it, with more atrial fibrillation, acute kidney injury and pulmonary embolism (Lincoff et al., 2023; PMID 37326322).
• Prostate effects — In a 36-month trial in older men with low testosterone, adding finasteride, which blocks DHT, limited the rise in prostate size and PSA seen with testosterone alone (Amory et al., 2004; PMID 14764753). An international expert consensus found that the evidence does not support an increased risk of prostate cancer with testosterone therapy (Morgentaler et al., 2016; PMID 27313122); the labels contraindicate it in known or suspected prostate cancer (Xyosted label), and the Endocrine Society evaluates prostate cancer risk during the first year of treatment (Bhasin et al., 2018; PMID 29562364).

What the Research Shows

Testosterone is among the most rigorously studied bioactive compounds in medicine. Key findings across decades of research:

• Supraphysiologic dose and muscle (Bhasin et al., NEJM 1996; PMID 8637535) — A randomized trial in 43 healthy men: 600 mg of testosterone enanthate a week for 10 weeks increased muscle size and strength even without exercise, and fat-free mass, muscle size and strength rose most with testosterone plus weight training. It tested one dose, not a dose range.
• Age-related decline (Harman et al., J Clin Endocrinol Metab 2001; PMID 11158037) — Baltimore Longitudinal Study of Aging. Demonstrated gradual testosterone decline with age, ~1–2% per year from 4th decade.
• TRT effects (T Trials, Snyder et al., NEJM 2016) — A coordinated set of seven double-blind placebo-controlled trials in symptomatic men 65 or older. A year of testosterone gave a moderate benefit in sexual function and some benefit in mood and depressive symptoms, and no benefit in vitality or walking distance; the companion trials reported effects on anaemia and bone density and none on cognition.
• Cardiovascular safety (TRAVERSE — Lincoff et al., NEJM 2023; PMID 37326322) — 5,246 men aged 45–80 with hypogonadism and CV risk; transdermal T vs placebo. Primary endpoint: noninferiority for MACE. Testosterone met noninferiority for MACE. Atrial fibrillation and nonfatal arrhythmia modestly increased.
• Endocrine Society 2018 Guidelines (Bhasin et al., J Clin Endocrinol Metab 2018; PMID 29562364) — It diagnoses hypogonadism only in men with symptoms and unequivocally, consistently low fasting morning testosterone, confirmed by a repeat test, and aims treatment at the mid-normal range; its harmonized normal range for healthy, nonobese men aged 19 to 39 is 264–916 ng/dL. The AUA guideline instead uses a total testosterone below 300 ng/dL on two early-morning tests and targets 450–600 ng/dL (Mulhall et al., 2018).
• Metabolic effects meta-analysis — TRT modestly improves fasting glucose, HbA1c, insulin resistance, and visceral adiposity in hypogonadal men. Small but measurable body-composition improvements.
• Bone density effects — TRT in hypogonadal men improves bone mineral density, particularly at the spine. Effect size smaller than bisphosphonates.
• Sexual function endpoints — Consistent improvement in libido, sexual activity, and erectile function in hypogonadal men across multiple trials. Effect size moderate.
• Prostate (long debate, current consensus) — An international expert consensus found that the evidence does not support an increased risk of prostate cancer with testosterone therapy (Morgentaler et al., 2016), and the AUA guideline tells patients there is no evidence linking the two (Mulhall et al., 2018). The labels still warn that men on androgens may be at increased risk and contraindicate testosterone in known or suspected prostate cancer (Xyosted label); the guidelines check prostate cancer risk during the first year of treatment (Bhasin et al., 2018).
• Cognitive endpoints — Mixed. TRT in hypogonadal men modestly improves verbal memory in some trials; other cognitive domains less consistently.
• Mood and depression — TRT can improve mood in hypogonadal men with depressive symptoms. Not a substitute for antidepressants in non-hypogonadal men with depression.
• Fertility preservation / HCG — The AUA guideline says clinicians may give hCG, 250 or 500 IU every other day, alongside testosterone: in one small study it kept intratesticular testosterone at baseline, and low-dose hCG has also been described as preserving sperm production in men on testosterone (Mulhall et al., 2018).
• Subcutaneous vs intramuscular — In a phase 2 study of 39 men with hypogonadism, weekly subcutaneous enanthate (50 or 100 mg) kept average testosterone in the normal range with lower peaks than a 200 mg intramuscular dose (Kaminetsky et al., 2015); the AUA guideline notes the subcutaneous route has been described for short-acting injections (Mulhall et al., 2018), and men's-health clinic protocols describe it for cypionate.

Human Data

The human TRT evidence base is vast. Key studies:

• Bhasin 1996 NEJM — 600 mg a week of testosterone enanthate and muscle in healthy men, with and without exercise.
• T Trials (2010s) — Seven coordinated NIH-funded trials in older hypogonadal men.
• TRAVERSE (2023; NEJM; PMID 37326322) — Cardiovascular safety pivotal trial.
• TIMES2 (Jones et al.) — TRT in men with T2D and metabolic syndrome.
• Registry studies — Long-term observational data on TRT outcomes across large health-system populations.
• Kaminetsky 2015 SubQ autoinjector study — Phase 2 subcutaneous T enanthate autoinjector validation (Xyosted pathway).
• Harman 2001 BLSA — Longitudinal natural history data on age-related T decline.
• Pharmacokinetic studies across ester types — Comparative PK of cypionate, enanthate, undecanoate, propionate, and transdermal formulations.
• Hematocrit monitoring literature — Multiple trials documenting TRT erythropoietic effect and polycythemia management strategies.
• PSA monitoring studies — Standard protocols for PSA surveillance during TRT.
• Fertility / HCG adjunct trials — Validation of HCG for preserving spermatogenesis during TRT.

Reconstitution & Storage

Testosterone cypionate and enanthate come as ready-made oil solutions, so nothing is mixed: cypionate in cottonseed oil at 100 or 200 mg/mL, in 1 mL and 10 mL vials (Depo-Testosterone label), and enanthate in sesame oil at 200 mg/mL, in 5 mL multi-dose vials (testosterone enanthate label).

• Storage — The labels list 20–25°C, protected from light (Depo-Testosterone label); Xyosted is kept at room temperature and not refrigerated or frozen (Xyosted label).
• Warming before injection — Crystals that form during storage below the labeled temperature redissolve when the vial is warmed and shaken, or rotated between the palms (Depo-Testosterone and testosterone enanthate labels).
• Injection technique (IM) — The labels describe slow, deep injection into the gluteal muscle, avoiding injection into a vessel (Depo-Testosterone and testosterone enanthate labels); the AUA guideline also lists the lateral upper thigh (Mulhall et al., 2018).
• Injection technique (SubQ) — Xyosted delivers 0.5 mL under the skin of the abdomen only (Xyosted label), through a five-eighths-inch 27-gauge needle (Kaminetsky et al., 2015).
• Injection frequency trade-off — The AUA guideline prefers smaller doses at shorter intervals, such as 100 mg weekly over 200 mg every 2 weeks, to limit time above or below the normal range, and links polycythemia and high estradiol at least partly to peak levels (Mulhall et al., 2018).
• Site reactions — Local injection-site reactions occur in 7–33% of men on short-acting injections (Mulhall et al., 2018); the Aveed label alternates left and right buttock between injections (Aveed label).
• Inspection — The labels describe a clear, colorless to pale yellow solution and say injectables are checked by eye for particles and discoloration before use; Xyosted is not used if cloudy or holding particles, while the enanthate label notes that a wet needle or syringe can cloud the solution without affecting potency (testosterone enanthate and Xyosted labels).

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Side Effects & Risks

• Erythrocytosis / polycythemia — The AUA guideline calls a rise in hemoglobin and hematocrit the most frequent adverse event of testosterone therapy. In five placebo-controlled trials it pooled, there were 19 polycythemia events among 1,094 men on testosterone and 1 among 1,093 on placebo; rises were largest with injections, and in one retrospective series 19% of men on injections, 12.5% on pellets and 5.4% on gels developed it (Mulhall et al., 2018). The Endocrine Society defines erythrocytosis as a hematocrit above 54% (Bhasin et al., 2018).
• Fertility suppression — The AUA guideline says testosterone therapy interrupts normal sperm production and can leave men with very low or no sperm counts. In the contraception studies it cites, sperm counts in 1,549 healthy men recovered in 67% within 6 months of stopping and in all within 24 months, but there are no good data for men with low testosterone, and some infertile men may never recover. It says clinicians may give hCG, 250 or 500 IU every other day, alongside testosterone; in one small study that kept intratesticular testosterone at baseline (Mulhall et al., 2018).
• Testicular atrophy — Listed among reactions reported in men who abuse anabolic steroids (Depo-Testosterone label).
• Estradiol elevation (aromatization) — Estradiol rises with testosterone: in men whose own hormones were suppressed and replaced with graded doses of testosterone gel, mean estradiol went from 3.6 to 33.3 pg/mL as testosterone went from 44 to 805 ng/dL (Finkelstein et al., 2013). The AUA guideline measures estradiol in men who develop breast symptoms or gynecomastia on treatment and in all men on an aromatase inhibitor (Mulhall et al., 2018).
• Gynecomastia — The labels say it may develop and occasionally persists in men treated for hypogonadism (Depo-Testosterone label).
• Acne and seborrhea — Both are on the labels' list of adverse reactions (Depo-Testosterone label); 2.7% of men reported acne in Xyosted's one-year study (Xyosted label).
• Androgenetic alopecia acceleration — Male pattern baldness is on the labels' list of adverse reactions (Depo-Testosterone label). Balding scalp holds more DHT than hairy scalp, and finasteride, which blocks DHT production, is approved for male pattern hair loss in men; its label lists sexual side effects that can continue after stopping, and depression and suicidal thoughts (Propecia label).
• Prostate effects — PSA and prostate volume rise slightly on treatment and plateau at 12 months (Saad et al., 2011); 12% of men in Xyosted's one-year study had a PSA increase (Xyosted label). An international expert consensus found that the evidence does not support an increased risk of prostate cancer (Morgentaler et al., 2016); the labels still warn that men on androgens may be at increased risk, contraindicate testosterone in known or suspected prostate cancer, and call for prostate cancer evaluation before and during treatment (Xyosted label).
• Cardiovascular (TRAVERSE summary) — In 5,246 men aged 45 to 80 with hypogonadism and heart disease or a high risk of it, a major cardiac event (cardiovascular death, nonfatal heart attack or stroke) occurred in 7.0% on testosterone gel and 7.3% on placebo, and each part of that composite was similar; atrial fibrillation, acute kidney injury and pulmonary embolism were more frequent on testosterone (Lincoff et al., 2023). The labels warn that testosterone can raise blood pressure, which can raise cardiovascular risk over time, and report blood clots in the legs and lungs (Xyosted label).
• Sleep apnea exacerbation — The labels warn that testosterone may worsen sleep apnea in some men, especially those with obesity or chronic lung disease (Xyosted label).
• Mood changes — In the T Trials, men 65 or older reported slightly better mood and fewer depressive symptoms on testosterone (Snyder et al., 2016); in healthy men given 600 mg a week for 10 weeks, mood and behavior did not change (Bhasin et al., 1996). The labels link anabolic steroid abuse to hostility, aggression and other serious psychiatric effects (Depo-Testosterone label), and the Xyosted label reports depression and suicidal thoughts and behavior in its trials (Xyosted label).
• Lipids — In a meta-analysis of 30 placebo-controlled trials, testosterone made inconsequential changes to all lipid fractions in men with low testosterone (Haddad et al., 2007); the labels say lipid changes may call for adjusting lipid drugs or stopping testosterone (Xyosted label). Oral methyltestosterone lowered HDL cholesterol (Shoskes et al., 2016), and dyslipidemia is among reactions reported with anabolic steroid abuse (Depo-Testosterone label).
• Liver toxicity — The labels tie peliosis hepatis, liver tumors and cholestatic hepatitis to prolonged high doses of oral 17-α-alkyl androgens such as methyltestosterone, and report multiple liver adenomas after long-term intramuscular enanthate; Xyosted and the oral undecanoate Jatenzo are not known to cause these effects (Xyosted and Jatenzo labels).
• Skin-to-skin transfer (gels) — The gel labels carry a boxed warning: children exposed to testosterone gel by skin contact have shown virilization, and women can be exposed too. The labels tell users to wash their hands after applying it, cover the site with clothing once dry, and wash the site before skin-to-skin contact (AndroGel label).
• Contraindications — The labels contraindicate testosterone in men with breast cancer or known or suspected prostate cancer and in pregnant women (Xyosted label), and the cypionate label adds serious heart, liver or kidney disease (Depo-Testosterone label). The Endocrine Society recommends against it in men planning fertility in the near term or with a prostate nodule, a PSA above 4 ng/mL (above 3 at high risk) without urological evaluation, elevated hematocrit, untreated severe obstructive sleep apnea, severe urinary symptoms, uncontrolled heart failure, a heart attack or stroke in the last 6 months, or thrombophilia (Bhasin et al., 2018).
• WADA / competitive sport — Banned under S1 (Anabolic Agents). Detection is standard via urinary T/E ratio and Carbon Isotope Ratio Mass Spectrometry.
• DEA Schedule III — A Schedule III controlled substance under the Controlled Substances Act (Depo-Testosterone label). Prescription-only; possessing it without a valid prescription is unlawful under federal law (21 U.S.C. § 844).

Supportive Nutrition & Supplements

The AUA guideline counsels all men with low testosterone on lifestyle changes as a treatment strategy (Mulhall et al., 2018).

• Protein — The labels say androgens improve nitrogen balance only when calorie and protein intake is sufficient (Depo-Testosterone label).
• Resistance training — In healthy men given 600 mg of testosterone enanthate a week, those who also lifted weights three times a week gained more fat-free mass, muscle size and strength than men in either group without exercise (Bhasin et al., 1996).
• Body composition / body fat — In the Baltimore Longitudinal Study of Aging, total testosterone was lower in men with a higher body mass index (Harman et al., 2001).
• Linked to low testosterone — The AUA guideline lists chronic narcotic use and chronic corticosteroid use among histories that call for a testosterone test (Mulhall et al., 2018), and the labels list toxic damage from alcohol among causes of testicular failure (Xyosted label).

What to Expect — Timeline

Individual response varies. The time course below comes from a review of treatment studies (Saad et al., 2011) and the AUA guideline (Mulhall et al., 2018).

• Week 1–2 — Insulin sensitivity may improve within a few days; red-cell and body-composition changes come later (Saad et al., 2011).
• Week 3–6 — Sexual interest rose after about 3 weeks and plateaued by 6, quality of life improved within 3–4 weeks, effects on depressive mood appeared after 3–6 weeks, and effects on lipids after about 4 weeks (Saad et al., 2011).
• Week 6–12 — Hematocrit generally rises over the first 6 months, then plateaus (Mulhall et al., 2018); the AndroGel labels re-check it 3 to 6 months after starting (AndroGel label). Changes in erections and ejaculation could take up to 6 months (Saad et al., 2011).
• Month 3–6 — Changes in fat mass, lean mass and muscle strength appeared within 12–16 weeks, and effects on depressive mood peaked after 18–30 weeks (Saad et al., 2011).
• Month 6–12 — Body-composition changes stabilized at 6–12 months, red-cell effects peaked at 9–12 months, and PSA and prostate volume rose slightly and plateaued at 12 months; effects on bone were detectable after 6 months (Saad et al., 2011).
• Year 1+ — Body-composition changes can continue marginally for years and bone effects for at least 3 (Saad et al., 2011); the AUA guideline measures testosterone and hematocrit every 6–12 months on stable treatment (Mulhall et al., 2018).
• Cessation — In contraception studies of 1,549 healthy men, sperm counts recovered in 67% within 6 months of stopping testosterone and in all within 24 months; the AUA guideline notes there are no high-quality data on recovery in men with low testosterone, and reports that hCG alone or with a SERM has helped men recover testosterone and sperm production after testosterone or anabolic steroid use (Mulhall et al., 2018).
• Non-responders — For men whose testosterone normalizes but whose symptoms do not improve, the AUA guideline discusses stopping therapy 3 to 6 months after it began (Mulhall et al., 2018).

Quick Compare — Testosterone vs HCG vs Enclomiphene vs Nandrolone

The most relevant comparators for testosterone in a male-hormonal-optimization context are (a) HCG (restores endogenous T without HPG suppression), (b) enclomiphene (SERM that raises endogenous T), and (c) nandrolone (a non-aromatizing anabolic steroid used off-label alongside TRT).

Practical interpretation:

• Testosterone vs HCG — Not substitutes. hCG acts like LH and stimulates the Leydig cells to make testosterone; TRT replaces testosterone directly. The AUA guideline describes low-dose hCG alongside testosterone to keep intratesticular testosterone and sperm production (Mulhall et al., 2018).
• Testosterone vs enclomiphene — SERMs block estradiol's negative feedback on LH, so the body makes more of its own testosterone; if testosterone stays low while LH is high, the testes are likely the problem and a higher SERM dose is unlikely to help (Mulhall et al., 2018). Enclomiphene is not FDA-approved (Drugs@FDA).
• Testosterone vs nandrolone — Not substitutes. Men's-health clinic protocols describe adding nandrolone to TRT at moderate doses; nandrolone decanoate is discontinued in the US (Drugs@FDA).
• Guideline view — The AUA guideline says testosterone should not be prescribed to men trying to conceive, and lists aromatase inhibitors, hCG, SERMs, or a combination for men with low testosterone who want to keep their fertility (Mulhall et al., 2018).

→ See HCG profile  •  → See Enclomiphene profile

Practical User Notes

• Confirmed diagnosis — The AUA guideline diagnoses testosterone deficiency from a total testosterone below 300 ng/dL on two early-morning tests plus symptoms or signs (Mulhall et al., 2018); the Endocrine Society requires symptoms plus consistently low fasting morning levels, confirmed by a repeat test (Bhasin et al., 2018), and the labels require two low morning levels on separate days (Depo-Testosterone label).
• Frequency over dose — The AUA guideline prefers smaller, more frequent injections, such as 100 mg weekly over 200 mg every 2 weeks, to limit time above or below the normal range (Mulhall et al., 2018).
• SubQ vs IM — In a phase 2 study of 39 men with hypogonadism, weekly subcutaneous enanthate (50 or 100 mg) restored normal testosterone with less variation than 200 mg intramuscular, through a 27-gauge needle (Kaminetsky et al., 2015); Xyosted is the approved subcutaneous form (Xyosted label).
• HCG and fertility — The AUA guideline lists hCG, aromatase inhibitors and SERMs as options for men with low testosterone who want to keep their fertility, and says clinicians may give hCG, 250 or 500 IU every other day, alongside testosterone (Mulhall et al., 2018).
• Estradiol suppression — In men whose own hormones were suppressed, blocking estradiol with anastrozole raised body fat and contributed to falling sexual function (Finkelstein et al., 2013); the AUA guideline advises against long aromatase-inhibitor use because of bone loss (Mulhall et al., 2018).
• Hematocrit management — The AUA guideline acts at a hematocrit of 54% or more, first by adjusting the dose (Mulhall et al., 2018); the Endocrine Society withholds testosterone until hematocrit returns to normal, then resumes at a lower dose, and calls phlebotomy also effective (Bhasin et al., 2018).
• PSA monitoring — The AUA guideline measures PSA before treatment in men over 40, then follows prostate cancer screening guidance by shared decision (Mulhall et al., 2018).
• Switching products — FDA does not rate cypionate and enanthate as therapeutically equivalent (Shoskes et al., 2016), and the AndroGel labels say their doses cannot be substituted with other topical testosterone products (AndroGel label).
• First level check — The AUA guideline measures testosterone after three to four cycles of a short-acting injection, and 2–4 weeks after starting a gel (Mulhall et al., 2018); Xyosted reached steady state by week 6, when its label measures the trough (Xyosted label).
• Warning signs on the labels — The labels describe leg pain, swelling, warmth and redness (possible deep vein thrombosis) and sudden shortness of breath (possible pulmonary embolism), and stop testosterone if a clot is suspected (Depo-Testosterone label).

Bloodwork & Monitoring

The AUA and Endocrine Society guidelines and the labels set out the monitoring below; practitioner protocols add some tests.

• Pre-TRT baseline — Two early-morning total testosterone measurements, LH, prolactin when LH is low or low-normal, hemoglobin and hematocrit (below 50% before starting), PSA in men over 40, and estradiol in men with breast symptoms (Mulhall et al., 2018); free testosterone when total is near the lower limit or SHBG is altered (Bhasin et al., 2018).
• At 3 months — Practitioner protocols describe repeating total testosterone (midway between injections), hematocrit, estradiol and PSA. The AUA guideline first measures testosterone 2–4 weeks after starting, or after three to four cycles of a short-acting injection (Mulhall et al., 2018); the AndroGel labels re-check hematocrit 3 to 6 months after starting (AndroGel label).
• At 6 months — Practitioner protocols describe repeating the full baseline panel.
• Then every 6–12 months — Total testosterone and hematocrit; PSA by shared decision under the AUA's prostate cancer screening guideline (Mulhall et al., 2018). The labels also check blood pressure and the lipid profile periodically (Xyosted label).
• Hematocrit 54% or higher — The AUA guideline adjusts the dose first when testosterone levels are high, and refers men with normal levels to a hematologist for possible phlebotomy (Mulhall et al., 2018); the Endocrine Society withholds testosterone until hematocrit is normal, then resumes at a lower dose (Bhasin et al., 2018).
• PSA rise >1.4 ng/mL in first year or >4 ng/mL absolute — The Endocrine Society refers to a urologist for a confirmed rise of more than 1.4 ng/mL above baseline in the first 12 months, a confirmed PSA above 4.0 ng/mL, or an abnormal rectal exam (Bhasin et al., 2018).
• Estradiol — Measured in men who develop breast symptoms or gynecomastia on treatment and in all men on an aromatase inhibitor (Mulhall et al., 2018).
• Bone density (DEXA) — Practitioner protocols describe a repeat scan at 1–2 years; the Endocrine Society repeats bone density tests after 1–2 years of testosterone in hypogonadal men with osteoporosis who are not at high fracture risk, before deciding on osteoporosis drugs (Bhasin et al., 2018).
• Sleep apnea — The Endocrine Society recommends against starting testosterone in untreated severe obstructive sleep apnea (Bhasin et al., 2018), and the labels warn it may worsen sleep apnea (Xyosted label).
• Fertility workup — The AUA guideline gives men interested in fertility a reproductive evaluation, with a testicular exam and FSH, before treatment, does not prescribe testosterone to men trying to conceive, and lists hCG, aromatase inhibitors and SERMs as options to keep fertility (Mulhall et al., 2018).

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References

1. Lincoff AM, Bhasin S, Flevaris P, Mitchell LM, Basaria S, Boden WE, Cunningham GR, Granger CB, Khera M, Thompson IM Jr, Wang Q, Wolski K, Davey D, Kalahasti V, Khan N, Miller MG, Snabes MC, Chan A, Dubcenco E, Li X, Yi T, Huang B, Pencina KM, Travison TG, Nissen SE; TRAVERSE Study Investigators. Cardiovascular Safety of Testosterone-Replacement Therapy. N Engl J Med. 2023;389(2):107-117. PMID: 37326322. DOI: 10.1056/NEJMoa2215025.
2. Bhasin S, Brito JP, Cunningham GR, Hayes FJ, Hodis HN, Matsumoto AM, Snyder PJ, Swerdloff RS, Wu FC, Yialamas MA. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715-1744. PMID: 29562364.
3. Bhasin S, Storer TW, Berman N, Callegari C, Clevenger B, Phillips J, Bunnell TJ, Tricker R, Shirazi A, Casaburi R. The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men. N Engl J Med. 1996;335(1):1-7. PMID: 8637535.
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