The Testosterone (TRT) Dose Calculator is a clinical tool designed for healthcare professionals to model dosing schedules for various testosterone replacement therapy formulations. It assists in protocol design by estimating weekly dosage, injection volumes, and potential serum level fluctuations for injectable esters, as well as estimating absorbed dosage for common transdermal products. It also provides a framework for interpreting follow-up lab results to guide dose adjustments.

• Dose per Injection (mg): The specific mass of testosterone ester administered in a single injection.
• Volume per Injection (mL): The volume of carrier oil required for the specified milligram dose, based on the product’s concentration (mg/mL).
• Total Weekly Dose (mg): The total amount of testosterone ester administered over a seven-day period, a standard metric for comparing protocols.
• Estimated Serum Levels (ng/dL): The tool provides rough estimations for trough (lowest point before next dose), peak (highest point after dose), and average serum testosterone levels. These are based on population pharmacokinetic models and individual results will vary.
• Lab Interpretation: For the Clinical Advisor tab, the tool offers potential interpretations for trough testosterone, estradiol, and hematocrit values, flagging results outside of typical target ranges for clinical consideration.

1. Injectable Dose Tab:

• Select the specific Testosterone Ester (e.g., Cypionate, Enanthate).
• Choose the Concentration of the product being used (e.g., 200 mg/mL).
• Enter either the intended Dose per Injection (mg) or the Volume per Injection (mL). The other field will auto-populate.
• Select the desired Injection Frequency (e.g., every 7 days).
• Click “Calculate” to see the full protocol summary.

2. Transdermal Dose Tab:

• Select the specific Transdermal Product (e.g., AndroGel 1.62%).
• Enter the number of Daily Applications (pumps or packets).
• Click “Calculate” to view the estimated applied and absorbed dose.

3. Clinical Advisor Tab:

• Enter the patient’s follow-up lab results for Trough Total Testosterone, Estradiol (E2), and Hematocrit (%).
• Click “Analyze” to receive suggestions based on established clinical targets.

Testosterone replacement therapy aims to restore serum testosterone levels to the normal physiologic range, typically targeting a mid-normal trough level (e.g., 450-650 ng/dL) in young, healthy men. Dosing is highly individualized.

Injectable Esters: Starting doses for testosterone cypionate or enanthate are often in the range of 100-200 mg every 1-2 weeks. However, more frequent administration of smaller doses (e.g., 50-100 mg weekly or 25-50 mg twice weekly) can produce more stable serum levels and may reduce side effects like high peak-related estradiol conversion or erythrocytosis. Shorter-acting esters like propionate require more frequent injections (every 1-3 days), while very long-acting esters like undecanoate are administered weeks apart.

Transdermal Gels: These provide a more stable, non-fluctuating daily dose. The initial dose is typically determined by the product’s prescribing information (e.g., two pumps of AndroGel 1.62%). Doses are adjusted based on follow-up lab work after 2-4 weeks.

When switching between different testosterone formulations, consider the pharmacokinetic properties of each product.

• Injectable to Injectable (Same Ester): To increase stability, a 100mg/week protocol can be switched to 50mg every 3.5 days without changing the total weekly dose.
• Injectable to Transdermal: Discontinue the injectable and start the transdermal product the day the next injection was due. A typical weekly injectable dose of 100 mg corresponds roughly to an absorbed daily dose of 5-7 mg from a transdermal product.
• Transdermal to Injectable: The first injection can be administered the day after the last transdermal application. Titrate dose based on lab work after 4-6 weeks.

Guidance on missed doses should be provided to the patient based on their specific protocol. General advice includes:

• For weekly injections: If the dose is missed by 1-2 days, administer it as soon as remembered and resume the normal schedule. If it is almost time for the next scheduled dose, skip the missed dose and resume the regular schedule. Do not double the dose.
• For transdermal gels: If a daily application is missed, apply it as soon as remembered unless it is almost time for the next dose. Do not apply double the amount to make up for a missed dose.

Testosterone therapy requires careful monitoring for potential adverse effects. All treatment decisions must be made by a qualified healthcare professional.

• Erythrocytosis: Testosterone can increase hematocrit. A hematocrit level exceeding 52-54% increases the risk of thromboembolic events. Monitoring is crucial, and may require dose reduction or therapeutic phlebotomy.
• Cardiovascular Risk: The potential for increased cardiovascular risk with testosterone therapy is a subject of ongoing research and debate. It should be used with caution in men with pre-existing cardiovascular disease.
• Transference Risk (Transdermals): Gel and solution products can be transferred to partners or children through skin contact, leading to virilization. Patients must be counseled on proper application and hygiene to prevent this.

1. Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715-1744. View Guideline
2. DEPO-TESTOSTERONE (testosterone cypionate) injection, solution [prescribing information]. Pfizer Inc. View on FDA.gov
3. ANDROGEL (testosterone gel) 1.62% [prescribing information]. AbbVie Inc. View on FDA.gov
4. AVEED (testosterone undecanoate) injection [prescribing information]. Endo Pharmaceuticals Inc. View on FDA.gov