Monitoring hematocrit is crucial in testosterone replacement therapy (TRT) due to the potential for significant increases in hematocrit levels, which can lead to adverse cardiovascular events.
Hematocrit changes in TRT
- Hematocrit increase: All types of testosterone therapies, including gels, patches, oral tablets, and injectables, have been associated with statistically significant increases in mean hematocrit compared to placebo
- Formulation differences: Intramuscular testosterone cypionate/enanthate are associated with a significantly higher increase in mean hematocrit compared to patches, but no differences in hematocrit between other formulations were detected
- Hepcidin suppression: Testosterone administration is associated with suppression of serum hepcidin, a peptide that regulates iron. This suppression is dose-dependent and more pronounced in older men, corresponding to a greater rise in hematocrit
Clinical implications
- Cardiovascular risk: Increases in hematocrit from baseline are associated with an increased risk of major adverse cardiovascular events (MACE) compared to men whose hematocrit remains stable while receiving TRT
- Polycythemia risk: Elevated hematocrit can result in polycythemia, a condition that can increase blood viscosity and potentially lead to thromboembolic events.
Monitoring recommendations
- Regular monitoring: Guidelines recommend regular monitoring of hematocrit levels in patients receiving TRT. This includes measurements before treatment, at 3–6 months, 12 months, and every 12 months thereafter
- Dose adjustment: If hematocrit levels exceed 54%, it is recommended to discontinue TRT and perform phlebotomy until hematocrit decreases to a safe level. TRT can be reintroduced at a lower dose once hematocrit has normalized
In conclusion, monitoring hematocrit is essential in TRT due to the potential for significant increases in hematocrit levels, which can lead to adverse cardiovascular events. Regular monitoring and appropriate dose adjustments can help mitigate these risks.