How often should testosterone levels be checked in patients with hypogonadism (low T) on testosterone (T) injections?

Testosterone Monitoring Frequency for Patients on Testosterone Injections

Check testosterone levels at 2-3 months after starting injections or any dose change, then every 6-12 months once stable therapeutic levels are confirmed. 1

Initial Monitoring Phase

For patients starting testosterone injections, the first clinical follow-up should occur at 1-2 months to assess treatment efficacy and symptom response, with formal testosterone level testing at 2-3 months. 2, 3 This initial period is critical because:

• Nearly half of men on testosterone therapy never have their levels checked after starting treatment, leading to suboptimal dosing or unnecessary exposure 1
• Approximately 49% of men with documented low testosterone before treatment remain biochemically hypogonadal after starting therapy, suggesting inadequate dosing or non-compliance 4

Timing of Blood Draw for Injectable Testosterone

For standard testosterone cypionate or enanthate injections, measure levels midway between injections (typically day 5-7 for weekly injections), targeting mid-normal range values. 1, 2, 3 This timing is essential because:

• Peak serum testosterone occurs 2-5 days after intramuscular injection 1, 2, 3
• Levels return to baseline by 10-14 days post-injection 1, 2
• Measuring at the midpoint provides the most accurate assessment of therapeutic adequacy 1, 2

Long-Term Monitoring Schedule

Once stable testosterone levels are confirmed on a given dose, monitoring every 6-12 months is typically sufficient. 1 The American Gastroenterological Association specifically recommends:

• Testing at 3-6 month intervals during the first year 3
• Annual monitoring thereafter if levels remain stable 3

Dose Adjustment Criteria

If clinical response is suboptimal and testosterone levels are in the low-normal range at the midpoint between injections, increase the dose. 1, 3 Key considerations include:

• Target testosterone levels should be in the mid-to-upper normal range for optimal symptom relief 3
• If maximal dosing fails to achieve adequate levels, consider switching from transdermal to intramuscular therapy (or vice versa) 1

Critical Safety Monitoring

At each monitoring visit, check hematocrit/hemoglobin and PSA in addition to testosterone levels. 1, 3 Safety parameters require:

• If hematocrit rises above the reference range, temporarily withhold therapy, reduce dose, or perform phlebotomy 1, 2, 3
• Monitor PSA with urologic referral if PSA increases >1.0 ng/mL in the first 6 months or >0.4 ng/mL per year thereafter 1
• Assess for prostate-related issues given concerns about converting occult prostate cancer to clinically apparent disease 3

Common Pitfalls to Avoid

The most critical error is failing to check post-treatment testosterone levels entirely—only 36% of men starting testosterone therapy have any follow-up level drawn. 4 Additional pitfalls include:

• Drawing levels at the wrong time in the injection cycle, leading to misinterpretation of peak or trough values 1, 2
• Failing to recognize that some patients exhibit abnormally high levels beyond the physiological range even with standard dosing 5
• Not reassessing patients who discontinue therapy early (40% stop after 1-2 prescriptions), as this may indicate inadequate dosing rather than treatment failure 4