What are the target hemoglobin (Hb) and hematocrit (Hct) levels in patients receiving testosterone therapy?

From the FDA Drug Label

1. 3 Polycythemia Increases in hematocrit, reflective of increases in red blood cell mass, may require lowering or discontinuation of testosterone. Check hematocrit prior to initiating treatment. It would also be appropriate to re-evaluate the hematocrit 3 to 6 months after starting treatment, and then annually If hematocrit becomes elevated, stop therapy until hematocrit decreases to an acceptable concentration.

The goal hematocrit while on testosterone is not explicitly stated, but it is recommended to stop therapy if hematocrit becomes elevated.

• The FDA label does not provide a specific target range for hemoglobin or hematocrit.
• It is recommended to check hematocrit prior to initiating treatment, 3 to 6 months after starting treatment, and then annually 1.
• If hematocrit becomes elevated, therapy should be stopped until it decreases to an acceptable concentration.
• In one clinical trial, a clinically notable increase in hemoglobin (≥ 19 g/dL) or hematocrit (≥ 58%) was reported in 2.3% and 2.8% of patients in the 100 mg dose group, respectively 1.

From the Research

For individuals on testosterone therapy, the goal hemoglobin and hematocrit levels should generally remain within the male reference range, with hemoglobin typically between 14-17.5 g/dL and hematocrit between 41-50%. If levels exceed these ranges, particularly if hematocrit rises above 54%, medical intervention may be necessary. This could include temporarily reducing testosterone dosage, switching to a different formulation (such as changing from intramuscular to transdermal), increasing the interval between doses, or performing therapeutic phlebotomy to remove excess red blood cells. Elevated levels are concerning because they increase blood viscosity and potentially raise the risk of thrombotic events like stroke or heart attack, as noted in a study published in 2024 2.

Key Considerations

• Regular monitoring is essential, typically every 3-6 months during the first year of therapy and then annually if levels remain stable, as suggested by a study in 2023 3.
• Staying well-hydrated before blood tests is important as dehydration can artificially elevate hematocrit readings.
• The choice of testosterone preparation can influence the extent of hematocrit increases, with some formulations potentially leading to less significant increases in hematocrit levels, as discussed in a review from 2025 4.
• Therapeutic phlebotomy, while sometimes recommended for reducing hematocrit in patients with testosterone therapy-induced erythrocytosis, lacks strong evidence supporting its efficacy and safety, and its potential pros and cons should be carefully weighed, as highlighted in a study from 2024 2.

Monitoring and Intervention

• Monitoring hematocrit levels is crucial during testosterone therapy to prevent complications associated with erythrocytosis.
• The incidence of severe erythrocytosis (hematocrit >54%) is rare, occurring in about 0.6% of patients on testosterone therapy, as found in a study published in 2023 3.
• Interventions such as adjusting testosterone dosage or formulation can help manage elevated hematocrit levels, and the decision to intervene should be based on individual patient risk factors and the potential benefits and harms of continuing testosterone therapy, as considered in a review from 2025 4.