Should testosterone gel (transdermal testosterone) be held prior to a lab draw?

Testosterone Gel Does Not Need to Be Held Prior to Lab Draw

For patients on transdermal testosterone gel, levels can be measured at any time without holding the medication, though timing relative to application affects interpretation. 1

Key Monitoring Principles

Timing Flexibility

• Transdermal testosterone preparations can be measured at any time of day without holding the dose 1
• This differs fundamentally from injectable testosterone, which requires specific timing (midway between injections) 1

Understanding Gel Pharmacokinetics

Peak vs. Trough Considerations:

• Peak testosterone levels occur approximately 6-8 hours after gel application (for patches specifically noted) 1
• Testosterone concentrations vary substantially with gel use, although not in a predictable way 1
• Recent research shows serum levels are significantly higher at +2 hours compared to +23 hours post-application 2

Steady-State Achievement:

• Serum testosterone reaches steady-state within the first 24 hours of gel application 3, 4
• Levels remain relatively stable day-to-day compared to injectable formulations 1

Practical Monitoring Approach

Initial Monitoring (First 2-3 Months)

• Draw testosterone levels 2-3 months after treatment initiation or any dose change 1
• Can be drawn at any time during the dosing interval 1
• Target mid-normal range (500-600 ng/dL) 1

Maintenance Monitoring

• Once stable levels confirmed, monitor every 6-12 months 1
• Continue drawing at any convenient time 1

Advanced Monitoring Strategy (Optional)

For patients with suboptimal response or dose optimization:

• Consider measuring at both +2 hours (peak) and +23 hours (trough) to assess adequacy throughout the day 2
• This dual-timepoint approach identifies patients who achieve adequate peak levels but drop below therapeutic range before next application 2
• In one study, 70% achieved adequate levels at +2 hours, but only 36.7% maintained adequate levels at +23 hours 2

Critical Caveats

Variable Absorption:

• Gel absorption is inherently variable and unpredictable between patients 1
• Approximately 60% of applied testosterone remains on skin after 8 hours, but only 14% after washing 5
• This variability is why levels can be checked anytime—there's no consistent pattern to predict 1

Morning Baseline Testing (Pre-Treatment Only):

• Morning draws (8-10 AM) are only required for diagnostic purposes before starting therapy, not for monitoring 1
• Once on gel therapy, this timing requirement no longer applies 1

Application Site Considerations:

• Surface area of application has modest impact (23% higher levels with four-site vs. one-site application) 4
• This reinforces that gel pharmacokinetics are complex and not strictly time-dependent 4

Bottom Line

Do not hold testosterone gel before lab draw. The guideline explicitly states levels can be measured at any time for patients on transdermal preparations, acknowledging the inherent variability in gel absorption makes strict timing unnecessary. 1 The goal is to confirm therapeutic levels are achieved and maintained, not to capture a specific pharmacokinetic timepoint.