What lab tests are required to start testosterone therapy?

Required Laboratory Tests for Testosterone Therapy Initiation

Prior to starting testosterone therapy, clinicians should measure total testosterone, hemoglobin/hematocrit, and PSA (in men over 40) to minimize risks and establish baseline values for monitoring. 1

Essential Baseline Laboratory Tests

Confirmation of Testosterone Deficiency

• Total testosterone levels (at least two morning measurements showing levels <300 ng/dL) 2
• Free testosterone (if total T is borderline or if conditions affecting sex hormone-binding globulin exist) 2
• Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) to distinguish primary from secondary hypogonadism 2

Cardiovascular and Hematologic Risk Assessment

• Hemoglobin/hematocrit (mandatory baseline measurement) 1, 2, 3
  • If hematocrit exceeds 50%, consider withholding therapy until etiology is investigated 1
  • Elevated hematocrit increases blood viscosity and risk of thromboembolic events 2, 3
• Assessment of cardiovascular risk factors (both fixed and modifiable) 1
  • Fixed: age, male gender
  • Modifiable: dyslipidemia, hypertension, diabetes, current smoking

Prostate Health Evaluation

• Prostate-specific antigen (PSA) in men over 40 years 1, 3
  • If elevated PSA at baseline, a second test is recommended to rule out spurious elevation 1
  • If two PSA levels raise suspicion for prostate cancer, consider reflex testing (4K or phi) and prostate biopsy with/without MRI before starting therapy 1
• Digital rectal examination to assess prostate 2

Additional Considerations

Fertility Assessment

• For men concerned about future fertility:
  • Testicular examination to evaluate size, consistency, and descent 1
  • Serum FSH measurement to assess underlying reproductive health status 1
  • Consider semen analysis if FSH is elevated 1
  • Genetic testing (karyotype and Y-chromosome analysis) for men with severe oligospermia or non-obstructive azoospermia 1

Metabolic Parameters

• Lipid profile (baseline cholesterol assessment) 2
• Fasting glucose or HbA1c (especially in patients with risk factors for diabetes) 2, 4

Monitoring Schedule After Initiation

• Testosterone levels: 2-3 months after starting therapy and after any dose changes 2
• Hemoglobin/hematocrit: 1-2 months after initiation, every 3-6 months during first year, then annually 2
• PSA: Follow-up according to standard prostate cancer screening guidelines 1

Important Cautions

• Injectable testosterone is associated with greater treatment-induced increases in hemoglobin/hematocrit compared to other formulations 1, 2
• If hematocrit exceeds 54% during therapy, intervention is warranted (dose reduction or temporary discontinuation) 1
• Testosterone therapy is contraindicated in men with breast or prostate cancer 3
• Testosterone therapy may suppress spermatogenesis and affect fertility 1, 3

By following these laboratory testing guidelines before initiating testosterone therapy, clinicians can establish appropriate baselines, identify contraindications, and develop a monitoring plan to optimize benefits while minimizing risks of treatment.