From the Guidelines
In patients on transdermal testosterone therapy, hematocrit or hemoglobin levels should be monitored along with PSA levels. This is based on the recommendation that at baseline, blood tests should be performed to measure PSA and the hematocrit or hemoglobin level, and a digital rectal examination should be performed 1. Testosterone therapy can stimulate erythropoiesis, potentially leading to polycythemia, which increases the risk of thromboembolic events.
Some key points to consider when monitoring patients on transdermal testosterone therapy include:
- Baseline hematocrit or hemoglobin should be measured before starting treatment, then at 3-6 months, and annually thereafter if stable 1.
- If hematocrit rises above the reference range, consideration should be given to temporarily withholding testosterone-replacement therapy, reducing the dosage, or performing phlebotomy 1.
- Monitoring for signs of prostate cancer is mandatory, given the widespread concern that testosterone treatment may stimulate the growth of an occult cancer 1.
- Other important considerations include assessing voiding symptoms, sleep apnea, and performing regular physical examinations, including digital rectal examinations 1.
It is essential to note that the goal of testosterone replacement therapy is to achieve mid- to upper-normal testosterone levels, and treatment should be individualized based on the patient's response to therapy 1. By monitoring these values and adjusting treatment as needed, healthcare providers can help ensure the safety and efficacy of testosterone replacement therapy while minimizing potential complications.
From the FDA Drug Label
Monitor serum testosterone, prostate specific antigen (PSA), hemoglobin, hematocrit, liver function tests and lipid concentrations periodically (5.1,5.3,5.9,5.13) The laboratory values that should be monitored while on testosterone therapy, in addition to a PSA level, are:
- Serum testosterone
- Hemoglobin
- Hematocrit
- Liver function tests
- Lipid concentrations 2
From the Research
Laboratory Values to Monitor
In addition to a PSA level, the following laboratory values should be monitored while on transdermal testosterone therapy:
- Hematocrit levels, as polycythemia is a common adverse effect of testosterone replacement therapy (TRT) and may predispose patients to adverse vascular events 3, 4, 5
- Hemoglobin concentration, as elevated levels may indicate polycythemia and increase the risk of major adverse cardiovascular events (MACE) and venous thromboembolic events (VTE) 3, 4
Rationale for Monitoring
Monitoring hematocrit and hemoglobin levels is essential to assess the risk of polycythemia and its associated complications, such as MACE and VTE 4, 5. The current guidelines recommend regular laboratory monitoring and discontinuing TRT or reducing the dose if the hematocrit exceeds 54% (hemoglobin ≥180 g/L) 3. However, some studies suggest that this threshold may not be appropriate for all patients, and other values may be more suitable in particular patient groups 5.
Clinical Considerations
When monitoring laboratory values, clinicians should consider the individual patient's risk factors and clinical presentation 6, 7. Testosterone replacement therapy should only be initiated after a thorough evaluation of the patient's symptoms and biochemical testosterone deficiency, and regular monitoring should be performed to assess the efficacy and safety of treatment 7.