Can I prescribe weekly testosterone injections for a patient with low morning total testosterone (<300 ng/dL) and symptoms such as low libido or erectile dysfunction, without fertility concerns?

Weekly Testosterone Injections for Hypogonadism

Yes, you can prescribe weekly testosterone injections for a patient with confirmed hypogonadism (morning total testosterone <300 ng/dL on two separate occasions) and symptoms of low libido or erectile dysfunction, provided the patient has no fertility concerns. Weekly dosing of testosterone cypionate or enanthate at 50-100 mg intramuscularly provides more stable testosterone levels than the traditional biweekly regimen and is supported by current guidelines. 1, 2

Diagnostic Confirmation Required Before Prescribing

Before initiating weekly injections, ensure the following criteria are met:

• Two separate morning testosterone measurements (8-10 AM) both <300 ng/dL to confirm persistent hypogonadism, as single measurements are insufficient due to diurnal variation and assay variability 1, 3
• Presence of specific symptoms: diminished libido and/or erectile dysfunction are the primary indications with proven benefit (standardized mean difference 0.35 for sexual function improvement) 1
• Measure LH and FSH to distinguish primary from secondary hypogonadism, which has critical implications for fertility counseling 1
• Confirm the patient does not desire fertility, as testosterone therapy causes azoospermia and is absolutely contraindicated in men seeking to conceive 1, 2

Weekly Dosing Regimen

Start with testosterone cypionate or enanthate 50-100 mg intramuscularly once weekly. 2 This dosing provides several advantages over the traditional biweekly regimen:

• More stable testosterone levels throughout the week, avoiding the "roller coaster" effect of biweekly injections where levels peak supraphysiologically at days 2-5 and return to baseline by days 13-14 1, 4, 5
• Lower risk of erythrocytosis compared to higher-dose biweekly injections, as weekly dosing reduces time spent in supraphysiologic ranges 1, 2
• Better symptom control with fewer fluctuations in energy and mood 2

The traditional biweekly regimen of 200 mg every 2 weeks is also acceptable but produces wider fluctuations, with many patients achieving androgen concentrations above normal ranges between days 2-7, then declining to basal levels by days 13-14. 6, 5

Administration Options

• Intramuscular injection sites: Anterolateral thigh (patient can self-administer) or gluteal muscle (requires assistance) 2
• Subcutaneous injection is an increasingly preferred alternative at the same weekly dose (50-100 mg), as it achieves therapeutic levels equivalent to intramuscular administration, is relatively painless, and allows easy self-injection 7
• Needle specifications: Use 18-gauge for drawing, 21-23 gauge 1-1.5 inch needles for intramuscular injection 2

Target Testosterone Levels and Monitoring

Target mid-normal testosterone levels of 450-600 ng/dL during treatment. 1, 3

• Initial monitoring: Measure testosterone levels at 2-3 months after initiation or any dose change 1, 2, 3
• Timing of blood draw for weekly injections: Measure midway between injections (days 3-4 after injection) targeting 500-600 ng/dL 1, 3
• Ongoing monitoring: Once stable, check testosterone every 6-12 months 1, 3
• Hematocrit monitoring: Check at each visit; withhold therapy if >54% and consider phlebotomy in high-risk cases 1, 2
• PSA and digital rectal exam: Monitor in men over 40 years 1, 2

Expected Outcomes

Set realistic expectations with your patient:

• Sexual function and libido: Small but significant improvements (standardized mean difference 0.35), typically seen within 3-6 months 1
• Quality of life: Modest improvements, primarily in sexual function domains 1
• Minimal or no benefit for physical functioning, energy, vitality, depressive symptoms, or cognition, even with confirmed hypogonadism 1
• Reevaluate at 12 months: If no improvement in sexual function, discontinue therapy to prevent unnecessary long-term exposure 1

Absolute Contraindications

Do not prescribe weekly testosterone injections if the patient has:

• Active desire for fertility preservation (use gonadotropin therapy instead: hCG plus FSH) 1, 2
• Hematocrit >54% at baseline 1, 2
• Active or treated male breast cancer 1
• Recent cardiovascular event within past 3-6 months (myocardial infarction or stroke) 1, 2
• Untreated severe obstructive sleep apnea 1

Critical Pitfalls to Avoid

• Never prescribe testosterone without confirming two separate morning testosterone measurements <300 ng/dL, as approximately 20-25% of men receiving testosterone therapy do not meet diagnostic criteria 1, 3
• Never start testosterone without explicitly confirming the patient does not desire fertility, as suppression of spermatogenesis can be prolonged and potentially irreversible 1
• Never use testosterone for weight loss, energy improvement, or athletic performance in men with normal testosterone levels—these are not evidence-based indications 1
• Do not ignore mild erythrocytosis (hematocrit 50-52%) in elderly patients or those with cardiovascular disease, as even modest elevations increase thrombotic risk 1

Alternative Formulation Consideration

If the patient prefers to avoid injections, transdermal testosterone gel 1.62% at 40.5 mg daily is the preferred first-line alternative, as it provides more stable day-to-day levels and carries significantly lower risk of erythrocytosis (15.4% vs 43.8% with injectable testosterone). 1, 2 However, gel costs approximately $2,135 annually versus $156 for intramuscular injections. 1