From the Guidelines
For testosterone replacement therapy (TRT) injections, follow-up lab monitoring should typically occur every 3-6 months for the first year, and annually thereafter if stable, as recommended by the most recent guidelines 1.
Key Monitoring Parameters
- Total testosterone levels should be measured every 6-12 months while on testosterone therapy 1
- Complete blood count to monitor for erythrocytosis
- Comprehensive metabolic panel to assess liver function
- Lipid panel
- PSA (prostate-specific antigen) in men over 40
- Estradiol levels should be checked if gynecomastia develops
Important Considerations
- Hemoglobin and hematocrit are particularly important as TRT can increase red blood cell production, with phlebotomy recommended if hematocrit exceeds 54%
- Testosterone levels should be maintained in the mid-normal range (400-700 ng/dL) for most patients
- More frequent monitoring may be needed for patients with comorbidities like cardiovascular disease, sleep apnea, or prostate issues
- Adjustments to dosing frequency or amount should be based on both lab results and symptom improvement, as clinical response varies between individuals despite similar blood levels
Baseline Evaluation
- Determine base-line voiding history or use standardized questionnaire
- Determine history of sleep apnea
- Perform digital rectal examination
- Perform blood tests for base-line testosterone levels, PSA, and hematocrit or hemoglobin
- Perform prostate biopsy if PSA level is above 4.0 ng/ml or digital rectal examination is abnormal 1
From the FDA Drug Label
Laboratory tests: Hemoglobin and hematocrit levels (to detect polycythemia) should be checked periodically in patients receiving long-term androgen administration. Serum cholesterol may increase during androgen therapy. The follow-up lab monitoring for testosterone (IM) injections should include:
- Hemoglobin and hematocrit levels to detect polycythemia
- Serum cholesterol levels to monitor for potential increases during androgen therapy 2
From the Research
Follow-up Lab Monitoring for TRT Injections
- The aim of testosterone replacement therapy (TRT) is to improve symptoms and signs of testosterone deficiency by increasing serum testosterone levels to a physiologic range 3.
- TRT has been associated with multiple benefits, but it also carries risks, such as secondary polycythemia, which is a known adverse effect of TRT 4, 5.
- Secondary polycythemia is characterized by an increase in hematocrit (Hct) levels, which can lead to an increased risk of venous thromboembolic events (VTE) and major adverse cardiovascular events (MACE) 6, 7.
- Studies have shown that different testosterone formulations can have varying effects on Hct levels, with injectables tend to produce the greatest effect 4, 5.
- Regular laboratory monitoring is recommended to assess the risk of polycythemia and adjust the treatment accordingly 3, 6.
- The evidence suggests that men with polycythemia while on TRT have a higher risk of MACE and VTE, and that developing polycythemia is an independent risk factor for these events 7.
- Some studies recommend that formulations with the smallest effect on blood parameters be used in patients at risk for veno-thrombotic events 5.
- Blood donation or phlebotomy may not be sufficient to maintain a hematocrit below 54% in men on TRT, and repeat donations may be necessary to reduce the risk of vascular events 6.