How to initiate topical testosterone (testosterone) therapy in a patient with unknown testosterone pellet dose?

Initiating Topical Testosterone When Pellet Dose is Unknown

Start topical testosterone gel at 50 mg daily (AndroGel 1%) or equivalent transdermal formulation, then measure testosterone levels at 2-3 months to guide dose titration, regardless of the unknown pellet dose. 1

Initial Dosing Strategy

When transitioning from testosterone pellets of unknown dose to topical therapy, begin with standard starting doses rather than attempting to match the pellet dose:

• AndroGel 1% should be initiated at 50-100 mg daily 1
• Testosterone patches (Androderm) can be started at 2-6 mg per 24 hours 1
• The standard starting dose of 50 mg daily for gel formulations is appropriate for most patients, as this represents the lower end of the therapeutic range and minimizes risk of supraphysiologic levels 1

Rationale for Standard Starting Dose

• Testosterone pellets provide variable absorption rates that differ significantly from transdermal preparations, making dose conversion unreliable 2
• Pellet formulations release testosterone over 3-6 months with fluctuating levels, while transdermal preparations provide more stable day-to-day testosterone concentrations 2
• Starting at a standard dose allows for individualized titration based on measured serum levels rather than guessing at pellet equivalency 1

Monitoring Protocol

Measure testosterone levels 2-3 months after initiating topical therapy to guide dose adjustment:

• Draw morning testosterone (between 8-10 AM) including total testosterone and free testosterone by equilibrium dialysis 2
• Target mid-normal testosterone values (450-600 ng/dL) 1
• Once stable levels are confirmed on a given dose, monitor every 6-12 months 1

Dose Titration

• If testosterone levels are below target at 2-3 months, increase gel dose from 50 mg to 75-100 mg daily 1
• The dose range for AndroGel 1% extends up to 100 mg daily 1
• Recheck levels 2-3 months after any dose adjustment 1

Formulation Selection Considerations

Transdermal gels are preferred over patches for most patients:

• Gels provide easy application and good skin tolerability 1
• Patches cause skin irritation in approximately 66% of users compared to only 5% with gels 1
• However, gels carry risk of transfer to partners or children through prolonged skin contact, requiring precautions such as covering the application site or washing hands thoroughly 2, 3

Cost considerations:

• Transdermal preparations cost significantly more than injectable testosterone (annual cost $2,135 for transdermal vs $156 for intramuscular) 2
• Among transdermal options, 53% of patients prefer gels over patches primarily due to convenience and ease of use 2

Critical Safety Precautions

• Warn patients explicitly about transfer risk to children and partners - unintentional transfer can cause precocious puberty in children 3
• Instruct patients to apply gel to clean, dry skin on shoulders, upper arms, or abdomen (not genitals) 2
• Cover application site with clothing after gel dries 2
• Wash hands immediately after application 2
• Monitor hematocrit and blood pressure, as testosterone can cause erythrocytosis and hypertension 4

Common Pitfalls to Avoid

• Do not attempt to calculate pellet-to-topical dose equivalency - the pharmacokinetics are too different to make reliable conversions 2
• Do not skip the 2-3 month follow-up - absorption from gels can be variable, and some patients may require dose adjustment 2
• Do not measure testosterone levels too early - allow 2-3 months for steady-state levels to be achieved 1