What baseline and follow‑up laboratory tests are recommended for a patient on testosterone therapy?

Routine Blood Work for Testosterone Therapy

For men on testosterone therapy, obtain baseline and follow-up testing of testosterone levels, hematocrit/hemoglobin, and PSA (in men ≥40 years), with monitoring every 3-6 months during the first year, then annually thereafter. 1

Baseline Laboratory Testing

Before initiating testosterone therapy, the following tests are essential:

Hormonal Assessment

• Testosterone levels (morning total testosterone) should be measured to confirm hypogonadism, ideally on at least 2 separate occasions 1, 2
• Gonadotropins (LH/FSH) should be measured to distinguish primary from secondary hypogonadism, though this is frequently underutilized in clinical practice (only 12% of patients receive this testing) 3

Prostate Monitoring

• PSA (prostate-specific antigen) measurement is mandatory at baseline 1, 4
• Digital rectal examination should be performed 1
• Prostate biopsy is required if baseline PSA >4.0 ng/mL or if digital rectal examination is abnormal 1

Hematologic Assessment

• Hematocrit or hemoglobin must be measured at baseline to detect pre-existing polycythemia 1, 5
• Testosterone therapy is contraindicated if hematocrit >50% 2

Additional Baseline Assessments

• Voiding history or standardized questionnaire for lower urinary tract symptoms 1
• Sleep apnea screening through history 1

Follow-Up Monitoring Schedule

First Year: Intensive Monitoring

• 1-2 months: Efficacy evaluation with testosterone level measurement for dosage adjustment if suboptimal response 1
• Every 3-6 months: Comprehensive monitoring including testosterone, hematocrit/hemoglobin, and PSA 1, 4

After First Year: Annual Monitoring

• Annually: Continue monitoring testosterone levels, hematocrit, and PSA in men ≥40 years 1, 4

Critical Monitoring Parameters

Testosterone Levels

• Target mid-normal range testosterone levels during treatment 2
• Adjust dosing based on levels and symptom response 1

Hematocrit Monitoring (High Priority for Safety)

• Testosterone-induced erythrocytosis (TIE) occurs frequently: 57% of patients reach hematocrit >0.46,23% exceed 0.50, and 5% exceed 0.54 6
• 46% of patients who develop elevated hematocrit do so within the first year, emphasizing the importance of close first-year monitoring 6
• Risk factors for TIE: Higher baseline BMI and higher baseline hematocrit values predict development of erythrocytosis 6
• Hematocrit increases are particularly pronounced with testosterone undecanoate (mean increase of 0.06) 6
• The FDA label specifically warns that hemoglobin and hematocrit should be checked periodically to detect polycythemia 5

PSA Monitoring and Prostate Cancer Surveillance

Multiple thresholds exist for triggering prostate biopsy during testosterone therapy 1:

• Biopsy indicated if PSA rises above 4.0 ng/mL (standard threshold) 1

• Alternative criteria include:

  • PSA increase >1.5 ng/mL/year or >0.75 ng/mL/year over 2 years (Endocrine Society approach) 1
  • PSA increase >1.0 ng/mL in first 6 months OR >0.4 ng/mL/year thereafter 1
  • PSA increase of 1.0 ng/mL in any single year 1

• Digital rectal examination should be performed at each monitoring visit 1

• Low threshold for biopsy if digital rectal examination shows nodule, asymmetry, or increased firmness 1

Clinical Symptom Assessment

At each follow-up visit, assess for:

• Urinary symptoms (worsening lower urinary tract symptoms) 1
• Sleep apnea (new onset or exacerbation) 1
• Gynecomastia (development or worsening) 1
• Sexual function and other hypogonadal symptoms for efficacy assessment 1

Common Pitfalls and Caveats

Inadequate Baseline Testing

Only 40% of men receive the recommended ≥2 testosterone measurements before therapy initiation, and only 46% receive follow-up testosterone measurements after starting therapy 3. This increases risk of overdiagnosis and inappropriate therapy use.

Insufficient Hematocrit Monitoring

Given that TIE can develop beyond the first year of therapy, annual monitoring must continue indefinitely, not just during the initial treatment period 6. Patients with higher baseline BMI and hematocrit require particularly vigilant monitoring 6.

PSA Monitoring Gaps

The mean PSA increase with testosterone therapy is small (0.30-0.43 ng/mL), but substantial increases warrant immediate evaluation 1. Different expert groups use varying PSA velocity thresholds, but all agree that changes on digital rectal examination or PSA >4.0 ng/mL require urologic evaluation 1.

Age-Specific Considerations

PSA and prostate monitoring should be performed at least annually in men ≥40 years receiving testosterone therapy 4. Younger patients may not require the same intensity of prostate surveillance but still need hematocrit monitoring.