From the Guidelines
The best time to check testosterone levels after an injection is midway between injections, targeting a mid-normal value (500-600 ng/dL) 1.
Key Considerations
- For patients receiving testosterone injections, levels should be measured midway between injections 1.
- The timing of testosterone measurements will vary depending on the preparation, but for injections, mid-cycle testing is recommended 1.
- Morning testing (between 8-10 AM) is generally preferred as testosterone naturally fluctuates throughout the day 1.
Rationale
Testosterone ester medications like cypionate and enanthate have a predictable release pattern in the body, with levels rising after injection, peaking within 1-2 days, and then gradually declining 1.
Important Points to Note
- Consistency is important—try to have your blood drawn at approximately the same time of day and same point in your injection cycle for each test 1.
- Your healthcare provider may adjust this timing based on your specific treatment goals, symptoms, and testosterone formulation 1.
- The goal of testing at mid-cycle is to provide the most representative picture of your average hormone levels 1.
From the Research
Time to Check Testosterone After Injection
- The timing of checking testosterone levels after injection is not explicitly stated in the provided studies, but it can be inferred based on the pharmacokinetics of different testosterone formulations.
- For intramuscular injections of testosterone esters, such as testosterone enanthate, plasma testosterone levels typically peak shortly after injection and then decline rapidly, becoming subnormal in the days before the next injection 2.
- In contrast, intramuscular injections of testosterone undecanoate have a more favorable pharmacokinetic profile, with plasma testosterone levels remaining stable and within the normal range for 12 weeks after injection 2.
- For subcutaneous testosterone injections, serum testosterone levels have been shown to remain stable between injections, with mean levels remaining well within the normal range 3.
- The American Family Physician recommends measuring testosterone levels after initiation of therapy to ensure that levels rise appropriately and to monitor for potential complications 4.
- The frequency of monitoring testosterone levels may vary depending on the individual patient and the specific formulation used, but it is generally recommended to check levels periodically to ensure that they remain within the normal range 5, 6.