What is the correct administration of testosterone injection for a patient with hypogonadism?

Correct Administration of Testosterone Injection

Injection Technique and Site

Testosterone enanthate or cypionate should be injected deeply into the gluteal muscle using standard intramuscular technique, with careful aspiration to avoid intravascular injection. 1

• The gluteal muscle is the FDA-approved and traditional injection site, ensuring proper absorption and minimizing local reactions. 1
• Care must be taken to slowly inject the preparation deeply into the muscle, following usual precautions for intramuscular administration. 1
• Subcutaneous injection is an effective alternative that can be self-administered, is less painful, and achieves stable therapeutic testosterone levels comparable to intramuscular injection. 2, 3
  • SC injections produce serum testosterone levels that remain stable between weekly injections, with mean total testosterone of 627 ± 206 ng/dL throughout the dosing interval. 3
  • All patients in studies achieved therapeutic levels with SC administration, with only minor and transient local reactions in 14% of patients. 2
  • Patients overwhelmingly prefer SC over IM injections (20 out of 22 patients had marked preference for SC), citing reduced pain and ability to self-administer. 2

Dosing Regimen

The standard dosing is 200 mg every 2 weeks or 300 mg every 3 weeks for testosterone enanthate or cypionate. 4, 1, 5, 6

• The FDA-approved dosing range is 50-400 mg every 2-4 weeks, with doses above 400 mg per month rarely required due to the prolonged action of the preparation. 1
• Injections more frequently than every 2 weeks are rarely indicated with traditional IM dosing. 1
• For SC administration, weekly dosing of 50-150 mg (median 75-80 mg) is effective and maintains stable levels. 2, 3
• The 200 mg every 2 weeks and 300 mg every 3 weeks regimens are most effective in suppressing LH to normal levels while minimizing injection frequency. 6

Common Pitfall to Avoid

Do not use the 400 mg every 4 weeks regimen, as it fails to adequately suppress LH and produces subtherapeutic testosterone levels between injections. 6

Monitoring Protocol

Measure testosterone levels midway between injections (days 5-7 for biweekly dosing), targeting mid-normal values of 500-600 ng/dL. 4, 7, 8

• Peak serum levels occur 2-5 days after injection, with return to baseline typically observed 10-14 days after injection. 4
• Check testosterone levels 2-3 months after treatment initiation or any dose change. 4, 7, 8
• Once stable levels are confirmed on a given dose, monitoring every 6-12 months is typically sufficient. 4, 8
• Monitor hematocrit periodically and withhold treatment if >54%, as erythrocytosis risk is higher with injectable formulations compared to transdermal preparations. 4, 8
• For men over 40 years, monitor PSA levels before initiating therapy and periodically during treatment. 4

Practical Administration Details

Use a dry needle and dry syringe, as moisture may cause the solution to become cloudy (though this does not affect potency). 1

• Inspect the solution visually before administration—testosterone enanthate should be clear, colorless to pale yellow. 1
• Do not administer if particulate matter or discoloration is present. 1
• For SC injections, use weekly administration with doses of 50-150 mg, which is effective across a wide range of body mass index (19.0-49.9 kg/m²). 2

Pre-Treatment Requirements

Confirm diagnosis of hypogonadism by ensuring serum testosterone concentrations below 300 ng/dL measured in the morning (8-10 AM) on at least two separate days. 7, 1

• Obtain free testosterone by equilibrium dialysis, particularly in patients with obesity where SHBG may be low. 7
• Measure LH and FSH to distinguish primary from secondary hypogonadism, as this has critical treatment implications for fertility preservation. 4, 8
• Document baseline hematocrit before initiating therapy, as hematocrit >54% is an absolute contraindication. 4

Critical Contraindication

Testosterone therapy is absolutely contraindicated in men actively seeking fertility, as it suppresses spermatogenesis and causes azoospermia—these patients require gonadotropin therapy (hCG plus FSH) instead. 4