Laboratory Monitoring for Men on Testosterone Therapy
Men on testosterone therapy require baseline and ongoing monitoring of testosterone levels, hematocrit/hemoglobin, and PSA, with initial follow-up at 1-2 months, then every 3-6 months during the first year, and annually thereafter. 1
Baseline Laboratory Tests (Before Starting Therapy)
Essential Tests
- Morning total testosterone levels measured on at least two separate occasions to confirm deficiency 2
- Hematocrit or hemoglobin to screen for polycythemia; withhold therapy if hematocrit exceeds 50% 1, 2
- PSA testing for all men over 40 years of age to exclude occult prostate cancer 1, 2
- Digital rectal examination should accompany PSA testing 1
Additional Tests Based on Clinical Context
- Luteinizing hormone (LH) to distinguish primary from secondary hypogonadism 2
- Prolactin if testosterone is low with low/normal LH to screen for hyperprolactinemia 2
- Follicle-stimulating hormone (FSH) in men interested in fertility preservation 2
- Estradiol if breast symptoms or gynecomastia are present 2
- Lipid profile to assess cardiovascular risk (optional but recommended) 1, 2
Special Screening Considerations
- Voiding symptoms assessment using International Prostatic Symptoms Score 1
- Sleep apnea history should be documented 1
- Pituitary MRI if total testosterone <150 ng/dL with low/normal LH 2
Follow-Up Monitoring Schedule
Timing of Follow-Up Visits
- First follow-up at 1-2 months after starting therapy to assess efficacy and adjust dosage 1, 3
- Every 3-6 months during the first year 1
- Annually thereafter once stable 1, 4
Parameters to Monitor at Each Visit
Laboratory Tests:
- Testosterone levels targeted to mid-to-upper normal range 1
- Hematocrit or hemoglobin at every visit; if hematocrit rises above reference range (particularly >54%), adjust or withhold therapy 1, 4, 5
- PSA monitoring at each follow-up visit 1, 2
- Lipid profile to monitor cardiovascular risk 4
Clinical Assessment:
- Symptomatic response to treatment 1
- Voiding symptoms 1
- Sleep apnea symptoms 1
- Gynecomastia 1
- Digital rectal examination 2
Critical Monitoring Thresholds and Actions
Hematocrit Management
Injectable testosterone carries the highest risk of erythrocytosis compared to other formulations 2, 6. Men receiving 200 mg biweekly injections have significantly higher rates of hematocrit elevation above 54% (8%) compared to 100 mg weekly (1%) 6. If hematocrit exceeds 54%, consider phlebotomy or dose adjustment 4.
PSA Monitoring Thresholds
PSA velocity requires close attention: an increase >1.0 ng/mL during the first six months or >0.4 ng/mL per year thereafter warrants urologic referral for possible biopsy 2. Substantial PSA increases require investigation for prostate cancer 1.
Testosterone Level Interpretation
For men on injection therapy, interpret results based on timing since last injection—peak levels occur 2-5 days after injection 2. Target testosterone levels to the mid-to-upper normal range for optimal response 1.
Common Pitfalls to Avoid
- Testing timing: Only 9% of practitioners obtain testosterone levels during the recommended morning window (7 AM-12 PM) 7, which can lead to inaccurate diagnosis
- Baseline hematocrit >50%: Therapy must be withheld until etiology is investigated 1, 2
- Starting therapy without recent testing: Many men initiate testosterone without appropriate baseline laboratory evaluation 8
- Fertility counseling: Testosterone therapy suppresses spermatogenesis; recovery typically requires 6 months or longer after cessation 4, 2