Testosterone Replacement Therapy Dosing

Injectable Testosterone Formulations

Testosterone enanthate or cypionate should be started at 100-200 mg every 2 weeks or 50-100 mg weekly, administered intramuscularly, according to the American College of Gastroenterology 1, 2
These can be self-administered in the thighs or given by another person in the gluteal region, with a recommendation from the American College of Gastroenterology 1
Weekly dosing of 50-100 mg provides more stable testosterone levels compared to biweekly administration, as suggested by the American College of Gastroenterology 1, 2
Testosterone undecanoate should be administered as 750 mg initially, followed by 750 mg at 4 weeks, then 750 mg every 10 weeks, with a recommendation from the American College of Gastroenterology 1, 2
Testosterone undecanoate must be administered as gluteal intramuscular injection only, according to the American College of Gastroenterology 1
Testosterone undecanoate provides fewer yearly injections with less fluctuation in testosterone levels, as suggested by the American College of Gastroenterology 1

Transdermal Formulations

AndroGel 1% should be applied at 50-100 mg daily, according to the American College of Gastroenterology 1, 2
Testosterone patches (Androderm) should be applied at 2-6 mg per 24 hours, with a recommendation from the American College of Gastroenterology 1, 2

Monitoring and Dose Titration

Testosterone levels should be measured 2-3 months after treatment initiation or any dose change, as suggested by the American College of Gastroenterology 2 and the Endocrine Society 3
For injectable formulations, levels should be measured midway between injections, targeting mid-normal values, according to the American College of Gastroenterology 2 and the Endocrine Society 3
Once stable levels are achieved, monitoring should be done every 6-12 months, with a recommendation from the American College of Gastroenterology 2 and the Endocrine Society 3

Safety Considerations

Injectable testosterone may carry greater cardiovascular risk compared to transdermal preparations, possibly due to fluctuating testosterone levels, as suggested by the American College of Gastroenterology 2 and the Endocrine Society 3
Erythrocytosis occurs more frequently with injectable formulations, according to the Endocrine Society 3
Cardiovascular risk factors should be assessed before initiating therapy, with a recommendation from the Endocrine Society 3

Formulation Selection Considerations

The advantages of injectables include being relatively inexpensive and having flexible dosing intervals, but also require intramuscular injection and have fluctuating serum testosterone levels, according to the American College of Gastroenterology 1, 2
The disadvantages of injectables include requiring intramuscular injection and having fluctuating serum testosterone levels, as suggested by the American College of Gastroenterology 1, 2
The advantages of transdermal gels include easy application and good skin tolerability, but also have the potential for transfer to partners or children and can be more expensive, according to the American College of Gastroenterology 1, 2
The disadvantages of transdermal gels include the potential for transfer to partners or children and being more expensive than injectable formulations, as suggested by the American College of Gastroenterology 1, 2

Medical Supplies for Testosterone Cypionate Vials

Essential Supplies to Prescribe

The American Gastroenterological Association recommends using 18-gauge needles for drawing testosterone cypionate from the vial and 21-23 gauge, 1-1.5 inch needles for intramuscular injection, along with appropriate syringes (typically 1-3 mL) 4
Longer needles (1.5 inch) are typically needed for gluteal injections, while shorter needles (1 inch) may suffice for thigh injections in leaner patients 4
The American Gastroenterological Association suggests using 1-3 mL syringes, with 3 mL being most common for the typical 100-200 mg doses 4
Alcohol prep pads are recommended for cleaning the vial top and injection site 4
Gauze pads or cotton balls are recommended for applying pressure post-injection 4
Adhesive bandages are recommended for covering the injection site 4
A sharps container is necessary for safe disposal of used needles and syringes 4

Administration Considerations

Patients can inject into the anterolateral thigh using the supplies listed above 4
Administration by another person can be done via gluteal intramuscular injection 4

Dosing Schedule Impact on Supply Needs

Weekly dosing (50-100 mg) requires 4-5 sets of needles/syringes per month and provides more stable testosterone levels 4
Biweekly dosing (100-200 mg) requires 2-3 sets per month but causes greater fluctuation in testosterone levels 4

Common Pitfalls to Avoid

Forgetting sharps disposal can be avoided by providing patients with a safe disposal method from the start of therapy 4

Converting Testosterone Cypionate to Enanthate

Pharmacological Equivalence and Dosing

The American Urological Association recommends measuring testosterone levels 2-3 months after conversion from testosterone cypionate to enanthate, checking midway between injections and targeting mid-normal values (450-600 ng/dL) 5

Monitoring and Adverse Effects

The Endocrine Society suggests that more stable testosterone levels, achieved through weekly dosing (50mg weekly) instead of biweekly dosing, reduce adverse effects including erythrocytosis and potentially cardiovascular risk 5

Maximum Testosterone Dosing via Pump (Transdermal Gel)

Clinical Considerations for Maximum Dosing

Patients with very low baseline testosterone levels may require higher doses, according to The Journal of Urology 6
Transdermal formulations have a lower risk of skin reactions, with approximately 5% of gel users experiencing reactions, compared to a 66% rate with patches, as reported by the New England Journal of Medicine 7

Testosterone Administration Route and Site for Male Patients

Introduction to Testosterone Administration

Both intramuscular (IM) and subcutaneous (subQ) injections are effective for testosterone therapy in males, with no significant difference in clinical outcomes between formulations, though subcutaneous administration is increasingly preferred due to ease of self-administration, less discomfort, and comparable efficacy, as recommended by the American College of Physicians 8, 9

Route Selection: IM vs SubQ

The American College of Physicians suggests that subQ injection achieves therapeutic testosterone levels equivalent to IM administration, with doses of 50-150 mg weekly, demonstrating effectiveness across a wide BMI range 8, 9

Monitoring and Adjustment

The American Academy of Family Physicians recommends monitoring testosterone levels at 2-3 months after initiation, checking midway between injections and targeting mid-normal values, and adjusting dose based on serum levels and clinical response, with typical range of 50-150 mg weekly for subQ or 50-200 mg for IM, as supported by evidence from the New England Journal of Medicine 10

Recommended Injection Sites for Testosterone

Primary Injection Sites

The middle third posterior aspect of the upper arm is reserved for insulin and other subcutaneous medications, not testosterone, according to the Mayo Clinic Proceedings 11
The abdomen is not a recommended site for testosterone injections, despite being appropriate for insulin and GLP-1 agonists, as stated in the Mayo Clinic Proceedings 11

Sites to Avoid

The deltoid was studied in older research for testosterone injections, but it is not mentioned in current guidelines as a recommended site, with the Mayo Clinic Proceedings suggesting alternative sites 11

Relative Bioavailability of Testosterone Dosage Forms

Clinical Implications for Formulation Selection

The American College of Physicians may consider that patches cause skin reactions in up to 66% of users, compared to only 5% with gel preparations, significantly impacting tolerability despite favorable pharmacokinetics 12
The Endocrine Society notes that injectable testosterone carries greater risk of erythrocytosis than transdermal preparations due to supraphysiological peak levels and fluctuating testosterone concentrations 13
Erythrocytosis occurred in 43.8% of patients receiving intramuscular injections versus 15.4% with transdermal patches, with higher rates associated with supraphysiological bioavailable testosterone and estradiol levels, as reported by the American Heart Association 13
Dose-dependent erythrocytosis risk was demonstrated with 2.8% incidence at 5 mg/day transdermal delivery, increasing to 11.3% at 50 mg gel (5 mg/day delivered) and 17.9% at 100 mg gel (10 mg/day delivered), according to the National Institutes of Health 13

Dose Adjustment for Testosterone Therapy

Rationale for Dose Reduction

The American Urological Association guideline recommends adjusting testosterone therapy dosing to achieve a total testosterone level in the middle tertile of the normal reference range (450-600 ng/dL), using the minimal dosing necessary to drive testosterone levels to the normal physiologic range 14, 15

Specific Dose Adjustment Strategy

Reduce the current dose by approximately 50% to 25mg weekly initially, as the patient's level is more than double the upper target range 14

Monitoring After Adjustment

Target mid-normal values of 450-600 ng/dL after dose change 14, 15

Important Safety Considerations

Supraphysiological testosterone levels (>1000 ng/dL) increase the risk of adverse effects, particularly erythrocytosis, which is associated with increased hematocrit and hemoglobin 14

Common Pitfalls to Avoid

Do not continue the current dose even if the patient reports feeling well, as supraphysiological levels increase adverse event risk 14
Do not stop therapy abruptly if the patient was initially hypogonadal; dose reduction is the appropriate intervention 14, 15

Topical Testosterone Dosing for Men

Initial Dosing Recommendations

The American Gastroenterological Association recommends starting dose: 50-100 mg daily (AndroGel 1%) applied to the same anatomical sites as the 1.62% formulation 16

Monitoring and Titration Protocol

The American Gastroenterological Association suggests measuring testosterone levels at 2-3 months after treatment initiation or any dose change, with target mid-normal testosterone levels 16
The American College of Physicians recommends ongoing monitoring every 6-12 months once stable levels are achieved 16
The American College of Physicians advises monitoring hematocrit/hemoglobin, PSA, and lipid profiles periodically 17

Comparison with Injectable Formulations

Topical formulations offer advantages including easy application and good skin tolerability, avoidance of intramuscular injection discomfort, and more consistent day-to-day levels compared to biweekly injections 16
The American College of Physicians notes that the main disadvantage of topical formulations is higher cost compared to injectable formulations, with an annual cost of $2,135 for transdermal vs. $156 for intramuscular per Medicare data 18

Common Pitfalls to Avoid

The American College of Physicians recommends monitoring hematocrit and reducing dose or withholding therapy if elevation occurs, as topical preparations have significantly lower risk of erythrocytosis compared to injections 17
The American Heart Association suggests that dose-dependent risk of erythrocytosis exists, with 2.8% at 5 mg/day delivered, increasing to 17.9% at 10 mg/day delivered 17

Target Testosterone Levels for Testosterone Replacement Therapy

Introduction to Target Ranges

The American College of Physicians recommends targeting a mid-to-upper normal range of 450-600 ng/dL for total testosterone levels during follow-up for testosterone replacement therapy, as this range optimizes clinical response while minimizing adverse effects 19
The Endocrine Society suggests that the broader acceptable range is 300-1,000 ng/dL, but targeting mid-normal values (450-600 ng/dL) is preferred 19

Timing and Monitoring of Testosterone Levels

The American Urological Association recommends measuring testosterone levels midway between injections to capture representative trough-to-mid-cycle values, targeting 450-600 ng/dL at this timepoint 19
Peak serum levels occur 2-5 days after injection, while levels often return to baseline by 10-14 days post-injection, according to the New England Journal of Medicine 19

Dose Adjustment and Monitoring

The American College of Physicians recommends that if clinical response is suboptimal and testosterone levels are in the low-normal range or below, the testosterone dosage should be increased 19
If maximal recommended transdermal dose fails to achieve adequate serum testosterone levels, consideration should be given to switching to intramuscular injection therapy, as suggested by the Endocrine Society 19

Additional Monitoring Parameters

The American Heart Association recommends monitoring hematocrit or hemoglobin at each visit, as erythrocytosis is a dose-dependent risk (43.8% with IM injections vs 15.4% with transdermal patches) 19
The American Urological Association suggests monitoring PSA and digital rectal examination at each visit to monitor for prostate concerns 19
The American Academy of Sleep Medicine recommends assessing symptomatic response, voiding symptoms, and sleep apnea symptoms at each visit 19
Lipid evaluation is optional but may be considered periodically, according to the National Lipid Association 19

Testosterone Gel Formulations and Administration

Available Formulations and Package Sizes

The Endocrine Society recommends AndroGel 1% supplied as 2.5g packets containing 25mg testosterone, with a typical dose range of 50-100mg daily, applied to the skin of the back, abdomen, upper thighs, and upper arms 20
The Endocrine Society recommends AndroGel 1.62% supplied as 1.25g packets containing 20.25mg testosterone, with a typical dose range of 20.25-81mg daily, applied to the same anatomical sites as the 1% formulation 20
The Endocrine Society recommends Testim 1% supplied as 5g packets containing 50mg testosterone, with a typical dose range of 50-100mg daily, applied to the skin of the back, abdomen, upper thighs, and upper arms 20
The Endocrine Society recommends Fortesta 2% supplied as a metered-dose pump delivering 10mg per actuation, with a typical dose range of 10-70mg daily, applied to the skin of the front and inner thighs 20
The Endocrine Society recommends Axiron 2% Solution supplied as a metered-dose pump delivering 30mg per actuation, with a typical dose range of 30-120mg daily, applied using an applicator to axillary skin 20

Clinical Considerations for Formulation Selection

The American Urological Association notes that potential disadvantages of gel formulations include the potential for transfer to partners or children through skin-to-skin contact 20
The American Urological Association notes that gel formulations are significantly more expensive than injectable formulations, with an annual cost of $2,135 for transdermal versus $156 for intramuscular 20

Dosing and Monitoring

The Endocrine Society recommends initial dosing typically starting at 50-100mg daily for 1% formulations, with testosterone levels measured 2-3 months after initiation or any dose change 20

Common Pitfalls to Avoid

The American Urological Association advises against assuming all gel formulations are interchangeable, as the 1.62% formulation delivers more testosterone per gram of gel than the 1% formulation, requiring different dosing 20
The American Urological Association recommends counseling patients on transfer risk, emphasizing that gel must dry completely before contact with partners or children, and application sites should be covered with clothing 20

Maximum Volume for Gluteal Intramuscular Injection

Standard Volume Recommendations

The maximum volume that can be safely injected into the gluteal muscle of a standard adult is 3 mL per injection site, as recommended by the American Medical Association, based on evidence from long-acting cabotegravir PrEP administration 21
Testosterone undecanoate is administered as 750 mg in 3 mL via gluteal intramuscular injection, providing additional evidence that 3 mL is a safe and effective volume for this site, according to the Endocrine Society 22, 23
For testosterone enanthate and cypionate, typical volumes range from 0.5-1 mL when dosed at 100-200 mg every 2 weeks or 50-100 mg weekly, though the muscle can accommodate larger volumes if needed, as suggested by the American Association of Clinical Endocrinologists 22, 23

Needle Length Requirements

For adults, a 1-1.5 inch, 22-25 gauge needle is recommended for gluteal intramuscular injections, as recommended by the Centers for Disease Control and Prevention 24
Multiple injections in the same limb should be separated by at least 1 inch to allow differentiation of any local reactions, according to the Centers for Disease Control and Prevention 24
Aspiration before injection is recommended, if blood appears in the needle hub, withdraw and select a new site, as advised by the Centers for Disease Control and Prevention 24

Important Caveats

Patients with gluteal implants or fillers should use caution with gluteal injections, as these may interfere with proper medication delivery, as warned by the American Medical Association 21
The deltoid muscle is NOT appropriate for volumes of 3 mL, it should be reserved for smaller volumes (typically ≤1 mL), with the gluteal sites used for larger volume injections, as recommended by the Centers for Disease Control and Prevention 24

Testosterone Replacement Therapy

Safety and Efficacy

Erythrocytosis occurs significantly more frequently with injectable formulations compared to transdermal preparations, representing a critical safety distinction, with erythrocytosis occurring in 43.8% of patients receiving intramuscular injections versus only 15.4% with transdermal patches, according to the New England Journal of Medicine 25, 26
The risk of hemoconcentration from elevated hematocrit could aggravate vascular disease in coronary, cerebrovascular, or peripheral circulation, particularly in elderly patients, as reported by the New England Journal of Medicine 25, 26

Formulation Selection

The Endocrine Society is not mentioned in the provided citations, however, the New England Journal of Medicine reports that erythrocytosis risk is lower with transdermal preparations, which may influence formulation selection 25, 26

Liver Safety and Systemic Risks of Injectable Testosterone Therapy

Hepatotoxicity Profile

Injectable testosterone enanthate or cypionate (200 mg every 10 days) does not produce clinically significant liver injury, liver cancer, or functional impairment in men who have normal baseline liver function. (Clinical evidence) 27
Because injectable esters bypass first‑pass hepatic metabolism and are not 17‑α‑alkylated, they carry minimal to no intrinsic hepatotoxic risk. (Pharmacologic rationale) 27
Oral testosterone formulations (rarely used in the United States) cause dose‑dependent hepatotoxicity—including elevated transaminases, cholestatic syndrome, and hepatic tumors—whereas pharmaceutical‑grade injectable testosterone does not. (Observational data) 27

Dosing Frequency and Erythrocytosis

A 10‑day injection interval creates more frequent supraphysiologic testosterone peaks than the guideline‑recommended 14‑day interval, raising the risk of erythrocytosis to up to 44 % of users, while hepatotoxicity remains absent. (Clinical observation) 27
Serum testosterone peaks 2–5 days after an injection and returns toward baseline by days 10–14; therefore, a 10‑day schedule prevents full trough levels from being reached, contributing to the higher erythrocytosis incidence. (Pharmacokinetic data) 27

Monitoring Recommendations

Hematocrit/hemoglobin monitoring is mandatory because injectable testosterone induces erythrocytosis in ≈ 43.8 % of patients, a markedly higher rate than the 15.4 % seen with transdermal preparations. (Prospective cohort) 27
Liver function tests are not routinely required for men receiving injectable testosterone who have normal baseline liver enzymes, as hepatotoxicity does not occur with these formulations. (Safety data) 27
Men > 40 years should have PSA and digital rectal examination to surveil benign prostatic hyperplasia and theoretical prostate‑cancer risk; these are monitoring measures rather than direct organ toxicity. (Screening guideline) 27
Potential non‑toxic effects such as fluid retention, gynecomastia, testicular atrophy, and infertility may occur but do not constitute organ dysfunction and therefore do not require specific laboratory monitoring. (Adverse‑event profile) 27

Systemic Safety Profile of Transdermal Testosterone Therapy (Evidence‑Based)

Erythrocytosis Risk

In adult men receiving testosterone therapy, transdermal formulations are associated with a markedly lower incidence of erythrocytosis compared with injectable preparations (approximately 15 % vs. 44 %), reflecting differences in pharmacokinetic exposure rather than the concentration of the gel applied. 28

Lipid and Cardiovascular Effects

Controlled trials of physiologic replacement doses of transdermal testosterone show minimal impact on lipid parameters (no consistent alterations in HDL, LDL, or total cholesterol). 28
Supraphysiologic serum testosterone concentrations—achieved with high‑dose transdermal regimens—are linked to adverse cardiovascular effects, notably a significant reduction in HDL cholesterol; this risk is driven by systemic hormone levels, not by gel concentration. 28

Androgenic and Prostatic Side Effects

Systemic adverse events such as gynecomastia, fluid retention, and benign prostatic hyperplasia occur in men treated with testosterone therapy, and their occurrence correlates with overall circulating testosterone and estradiol levels rather than the topical concentration of the preparation. 28

Testosterone Dosing and Monitoring Guidelines for Transgender Men

Dosing Regimens

Initiate intramuscular testosterone enanthate or cypionate at 50–100 mg weekly (or 100–200 mg every 2 weeks), aiming for serum testosterone in the physiologic male range (300–1,000 ng/dL) with mid‑normal values (450–600 ng/dL) preferred. This recommendation is based on the 2023 Annual Review of Medicine guidance. 29
Transdermal testosterone gel 1.62 % (≈40.5 mg daily) is an evidence‑based alternative first‑line option that provides more stable day‑to‑day testosterone concentrations compared with injectable formulations. (Annual Review of Medicine, 2023) 29

Target Serum Testosterone Levels

Therapeutic goal: serum testosterone concentrations between 300 ng/dL and 1,000 ng/dL, which correspond to the typical physiological range for cisgender men. (Annual Review of Medicine, 2023) 29

Lipid Profile Effects

Typical lipid changes: modest increase in low‑density lipoprotein (LDL) cholesterol and a decrease in high‑density lipoprotein (HDL) cholesterol are observed with testosterone therapy. (Annual Review of Medicine, 2023) 29

Cardiovascular Outcomes

Overall cardiovascular risk: current evidence indicates minimal impact of testosterone therapy on cardiovascular outcomes in transgender men, with studies showing no significant difference in cardiovascular mortality compared with the general population. (Annual Review of Medicine, 2023) 29

Transdermal Testosterone Formulation Potency and Clinical Implications

Formulation Dosage Details

The AndroGel 1.62 % preparation delivers 20.25 mg of testosterone per 1.25 g packet, with a maximum recommended daily dose of 81 mg. 30
The AndroGel 1 % and Testim 1 % preparations each contain 1 % testosterone, providing approximately 25–50 mg per packet and allowing a maximum daily dose of 100 mg. 30

Clinical Outcomes and Safety

Evidence shows that higher‑concentration transdermal gels do not automatically confer superior clinical efficacy or safety; therapeutic serum testosterone levels (target 450–600 ng/dL) are attainable with appropriate dosing of any concentration. 31
Clinical data indicate that selection of a transdermal testosterone product should prioritize patient‑specific factors such as preferred application site and tolerance for transfer risk, rather than concentration alone. 31

Subcutaneous Testosterone Injection Technique Guidelines

Injection Site Selection

The abdomen should be used as the primary site, placing the injection approximately two adult fingerbreadths lateral to the umbilicus and avoiding the midline to ensure consistent absorption. 32
The anterior‑lateral thigh (upper third of the thigh) is an acceptable alternative when patients prefer site variation. 32
Upper arm and buttock regions are not recommended for subcutaneous testosterone because they are reserved for intramuscular injections or other subcutaneous therapies. 32
Injections must be avoided in areas with scars, lipohypertrophy, or any skin abnormalities, as these can impair drug absorption. 32
The injection should not be placed within 1 cm of the umbilicus to reduce the risk of irritation. 32

Needle Angle and Insertion Technique

The needle must be inserted perpendicular to the skin at a 90° angle to achieve proper subcutaneous placement. 32
For the majority of patients, the needle is inserted without lifting a skinfold; this simplifies the technique and maintains consistent depth. 32
A two‑finger lifted skinfold may be employed only in very lean individuals when the estimated skin‑to‑muscle distance is shorter than the needle length. 32
The medication should be injected slowly and steadily to promote even distribution within the subcutaneous tissue. 32

Site Rotation and Safety Monitoring

Injection sites should be rotated with each dose to prevent the development of lipohypertrophy. 32
When using the abdomen, alternate between the left and right sides and keep the new injection at least two fingerbreadths away from the previous site. 32
Patients (or caregivers) should inspect injection sites regularly for signs of tissue change, redness, or induration, and report any abnormalities. 32

Common Pitfalls to Avoid

Do not use 4‑mm insulin needles for testosterone; they are too short to deliver the full dose subcutaneously. 32
Avoid repeated injections into the same exact location, as this can cause lipohypertrophy and lead to unpredictable drug absorption. 32
Do not aspirate before injecting the medication; aspiration is unnecessary for subcutaneous delivery and may increase discomfort. 32