What laboratory tests should a 38-year-old male with hypogonadism undergo prior to starting testosterone therapy?

Laboratory Tests Required Before Starting Testosterone Therapy in a 38-Year-Old Male with Hypogonadism

Before initiating testosterone therapy in a 38-year-old male with hypogonadism, several essential laboratory tests must be performed, including luteinizing hormone (LH), prolactin, hemoglobin/hematocrit, and assessment of cardiovascular risk factors. 1

Core Laboratory Tests

• Luteinizing Hormone (LH): Measure serum LH levels to determine if hypogonadism is primary (testicular) or secondary (hypothalamic-pituitary) in origin. This helps establish the etiology and guides treatment approach. 1

• Prolactin: Measure serum prolactin levels, especially in patients with low testosterone combined with low or low/normal LH levels to screen for hyperprolactinemia, which could indicate pituitary tumors. 1

• Hemoglobin/Hematocrit: Baseline measurement is mandatory before starting therapy. If hematocrit exceeds 50%, consider withholding testosterone therapy until the cause is investigated. 1, 2

• Cardiovascular Risk Assessment: Evaluate for atherosclerotic cardiovascular disease (ASCVD) risk factors, including both fixed (age, male gender) and modifiable factors (dyslipidemia, hypertension, diabetes, smoking). 1

Additional Tests Based on Age and Clinical Factors

• PSA (Prostate-Specific Antigen): For men over 40 years of age, PSA should be measured to exclude prostate cancer. Since the patient is 38, this may not be immediately required but should be considered if there are any prostate-related concerns. 1, 2

• Estradiol: Measure if the patient presents with breast symptoms or gynecomastia prior to starting testosterone therapy. 1

Fertility Considerations

• Follicle-Stimulating Hormone (FSH): If the patient is interested in preserving fertility, measure FSH to assess reproductive health status. 1

• Semen Analysis: Consider if the patient has fertility concerns, especially with elevated FSH levels which may indicate impaired spermatogenesis. 1

• Reproductive Genetics Testing: Offer karyotype testing and Y-chromosome analysis for microdeletions if severe oligospermia (<5 million sperm/mL) or non-obstructive azoospermia is detected. 1

Special Considerations

• Pituitary MRI: Consider if total testosterone is <150 ng/dL with low or low/normal LH levels, regardless of prolactin levels, to rule out non-secreting adenomas. 1

• Lipid Profile: Consider baseline measurement as part of cardiovascular risk assessment. 2, 3

• Liver Function Tests: Consider baseline assessment, particularly if oral testosterone formulations are being considered. 3, 4

Monitoring During Treatment

Once therapy begins, regular monitoring is essential:

• Hemoglobin/Hematocrit: Re-evaluate 3-6 months after starting treatment, then annually. If hematocrit exceeds 54% during treatment, intervention is required (dose reduction or temporary discontinuation). 1, 2

• Testosterone Levels: Monitor to ensure levels reach the mid-normal range. 5

Potential Pitfalls and Caveats

• Polycythemia Risk: Injectable testosterone is associated with the greatest treatment-induced increases in hemoglobin/hematocrit. 1, 2

• Fertility Impact: Testosterone therapy can suppress spermatogenesis through feedback inhibition of pituitary FSH. Patients interested in future fertility should be counseled about this risk. 1, 2

• Cardiovascular Risk: Some studies have reported increased risk of major adverse cardiovascular events with testosterone therapy, though evidence is inconclusive. 2

• Prostate Cancer Screening: While not required for men under 40 without risk factors, baseline PSA may still be considered as part of comprehensive evaluation. 1, 6