From the Research
Anastrozole (Arimidex) is typically dosed at 0.5 to 1 mg once or twice weekly for hypogonadal males on testosterone therapy who develop elevated estradiol levels. The medication works by inhibiting the aromatase enzyme that converts testosterone to estradiol, helping to manage estrogen-related side effects like gynecomastia, fluid retention, and mood changes. Treatment should be initiated when estradiol levels exceed 40-50 pg/mL or when estrogen-related symptoms appear despite normal levels, as suggested by the most recent study on the management of estrogen levels in men treated with testosterone therapy 1.
Key Considerations
- Dosing should be individualized based on laboratory monitoring, with estradiol levels checked 4-6 weeks after starting treatment.
- The goal is to maintain estradiol between 20-30 pg/mL, as excessively low levels can negatively impact bone health, lipid profiles, and cognitive function, as noted in a study on the coadministration of anastrozole with testosterone pellets 2.
- Patients should be monitored for potential side effects including joint pain, decreased bone mineral density, and lipid abnormalities.
- Anastrozole should only be used when clinically indicated by symptoms or laboratory values, not as routine prophylaxis with testosterone therapy, as highlighted in a survey of ISSM members on the treatment of estrogen levels in hypogonadism 1.
Monitoring and Adjustment
- Estradiol levels should be monitored regularly to adjust the dosage of anastrozole and maintain optimal levels.
- The use of anastrozole in combination with testosterone therapy can help sustain therapeutic testosterone levels and increase the interval between testosterone pellet insertions, as shown in a study on the coadministration of anastrozole with testosterone pellets 2.
- The most common medication prescribed for symptomatic hyperestrogenemia is anastrozole, but starting doses can vary significantly, ranging from 1 mg weekly to 1 mg daily, as reported in a survey of ISSM members 1.
Clinical Decision Making
- The decision to use anastrozole should be based on individual patient needs and symptoms, rather than as a routine part of testosterone therapy.
- Clinicians should consider the potential benefits and risks of anastrozole, including its effects on bone health, lipid profiles, and cognitive function, as well as its potential side effects, when making treatment decisions, as discussed in a review of evidence-based medicine on testosterone replacement therapy 3.