What hormone lab should I order for a patient undergoing gender transition?

Hormone Laboratory Monitoring for Transgender Patients

For transgender patients on hormone therapy, order testosterone and estradiol levels every 3-6 months during the first year, then annually if stable, along with baseline and periodic monitoring of complete blood count, comprehensive metabolic panel, lipid panel, and glucose/HbA1c. 1, 2

Initial Baseline Laboratory Assessment

Before initiating hormone therapy, obtain the following baseline labs 1, 2:

• Complete blood count (CBC) - establishes baseline hemoglobin/hematocrit before expected changes 3, 1
• Comprehensive metabolic panel - includes liver function tests and creatinine 1, 2
• Lipid panel - assesses cardiovascular risk factors 1, 2
• Glucose or hemoglobin A1c - screens for diabetes risk 1, 2
• Morning serum total testosterone - establishes baseline hormone levels 1
• Estradiol (if initiating feminizing therapy) - provides baseline reference 2

Ongoing Hormone Level Monitoring

For Transgender Women (Feminizing Therapy)

• Target testosterone <50 ng/dL to achieve adequate suppression 2
• Target estradiol in the cisgender female reference range (typically 100-200 pg/mL) 2
• Check levels every 3-6 months during the first year, then annually if stable 2
• Morning testosterone levels are preferred for consistency 1

For Transgender Men (Masculinizing Therapy)

• Target testosterone 300-1,000 ng/dL (typical physiological range for cisgender men) 3
• Check levels every 3-6 months during the first year, then annually if stable 3, 2
• Morning levels provide the most accurate assessment 1

Critical Safety Monitoring Labs

Hematologic Monitoring

• CBC every 3-6 months initially for transgender men on testosterone, as hemoglobin typically increases to male reference range within 3 months 3
• Watch for erythrocytosis (elevated hematocrit) in transgender men - this is the most common hematologic complication 3
• RBC indices stabilize within 6 months of hormone therapy initiation 4
• For transgender women, expect hemoglobin to decrease by 3.0-5.5% 2

Metabolic and Cardiovascular Monitoring

• Lipid panel every 3-6 months initially, then annually 1, 2
  • In transgender men: expect increased LDL and triglycerides, decreased HDL 3
  • In transgender women: HDL may increase beyond the first year 4
• Liver function tests - especially important with oral estrogen formulations 1, 2
• Glucose/HbA1c monitoring - testosterone can affect insulin sensitivity 1

Electrolyte Monitoring (Specific to Anti-Androgen Use)

• Potassium levels if using spironolactone at doses >50 mg daily, or if taking ACE inhibitors, ARBs, NSAIDs, or digoxin 2
• At starting doses of 25 mg spironolactone, routine potassium monitoring is unnecessary in young healthy individuals 2

Laboratory Value Interpretation: Critical Pitfall

After >1 year of hormone therapy, interpret laboratory values based on the patient's affirmed gender, not assigned sex at birth. 3 For example:

• A transgender man on testosterone with hemoglobin of 17 g/dL should be compared to male reference ranges, not flagged as "high" based on female ranges 5, 3
• Consider using cystatin C instead of creatinine for kidney function assessment, as it is less dependent on muscle mass changes from hormone therapy 3

Timeline for Laboratory Changes

Most analytes reach stable levels within 6 months (RBC indices, creatinine), while others continue changing long-term 4:

• RBC indices stabilize by 6 months 4
• HDL and platelets may increase beyond 1 year in transgender women 4
• LDL may increase beyond 1 year in transgender men 4

If hormone therapy is discontinued, laboratory values typically return to baseline around 10 weeks 4

Monitoring Schedule Algorithm

1. Baseline (before starting hormones): CBC, CMP, lipids, glucose/HbA1c, testosterone, estradiol 1, 2
2. 3 months: Testosterone and estradiol levels, CBC 3, 2
3. 6 months: Full panel (CBC, CMP, lipids, hormones) 2
4. Every 3-6 months during year 1: Hormone levels and CBC 2
5. Annually after year 1 (if stable): Full panel 2