Anastrozole Use in Testosterone Replacement Therapy

Introduction to Anastrozole and TRT

The American Urological Association guideline on testosterone deficiency makes no mention of aromatase inhibitor co-administration, focusing instead on testosterone formulations, monitoring, and contraindications 6
No major endocrine or urology society (American Urological Association, Endocrine Society, American College of Physicians) has published formal protocols for anastrozole use alongside testosterone therapy 1

Before initiating any anastrozole-TRT combination, evaluate baseline fracture risk and bone mineral density, as anastrozole increases bone loss risk 1
Monitor PSA and digital rectal examination for prostate health, hematocrit or hemoglobin levels, lipid profile, and voiding symptoms assessment before starting anastrozole-TRT combination 7
Anastrozole should NOT be used in premenopausal women for hormone management, and is relatively contraindicated in patients with history of osteoporosis or severe bone loss 1

The guideline-supported approach is testosterone therapy alone with appropriate monitoring, with transdermal testosterone gel (40.5 mg daily) as the preferred first-line formulation 8
Target mid-normal testosterone levels (500-600 ng/dL) and monitor testosterone levels 2-3 months after initiation, then every 6-12 months once stable 8

Bone health is a major concern, as anastrozole increases fracture risk (11.0% vs 7.7% with tamoxifen in breast cancer trials) 4
Fertility considerations - men interested in future fertility should avoid this combination entirely, as both testosterone and anastrozole can affect spermatogenesis 8