What baseline blood work should be ordered for a 21-year-old female-to-male (FTM) patient initiating hormone therapy?

Baseline Blood Work for Female-to-Male Hormone Therapy

For a 21-year-old patient initiating testosterone therapy, you should order: complete blood count (CBC) with hemoglobin/hematocrit, comprehensive metabolic panel (CMP) including liver enzymes and creatinine, lipid panel, hemoglobin A1c, and baseline testosterone level. 1

Essential Baseline Laboratory Tests

Hematologic Assessment

• Measure hemoglobin and hematocrit before starting testosterone therapy, as testosterone will increase red blood cell production and hemoglobin levels toward male reference ranges within 6 months 1
• Baseline hematocrit >50% warrants investigation before initiating therapy 1
• This establishes a reference point since hemoglobin typically increases to male reference ranges in patients on testosterone 1

Metabolic and Hepatic Function

• Order a comprehensive metabolic panel including liver enzymes (AST, ALT, alkaline phosphatase) and creatinine 1
• Liver enzyme measurements shift toward the affirmed gender reference range after 12 months of testosterone therapy 1
• Creatinine levels will increase toward male reference ranges due to increased muscle mass (approximately 4 kg increase in lean body mass after 1 year) 1

Cardiovascular Risk Assessment

• Obtain a lipid panel to assess baseline cardiovascular risk factors 1
• High-density lipoprotein values significantly increase beyond 1 year on testosterone, while alanine aminotransferase values also increase 1
• Screen for modifiable cardiovascular risk factors including dyslipidemia, hypertension, diabetes, and smoking status 1

Endocrine Baseline

• Measure baseline testosterone level to document pre-treatment values 1
• This provides a reference point for monitoring therapeutic response and ensures levels reach physiologic male ranges during treatment 1

Glucose Metabolism

• Check hemoglobin A1c to screen for diabetes or prediabetes 1
• The reference range for hemoglobin A1c is not sex-specific, but baseline assessment is important for cardiovascular risk stratification 1

Important Clinical Considerations

Monitoring Framework

• After initiating testosterone, laboratory values will shift toward male reference ranges over time, with most changes stabilizing within 6-12 months 1
• For patients on testosterone >12 months, interpret most laboratory values using male reference ranges 1
• If testosterone is discontinued for >3 months, laboratory values typically revert to female reference ranges 1

Common Pitfalls to Avoid

• Do not use cystatin C routinely for baseline assessment unless specifically indicated, as it is less dependent on muscle mass but not widely available 1
• Electrolyte monitoring uses non-sex-specific reference ranges, though fluctuations may occur if spironolactone is used concurrently 1
• Document the dose, route, and duration of testosterone therapy in the medical record, as these factors influence how laboratory values should be interpreted over time 1

Risk Stratification

• Assess for metabolic syndrome components, as these are associated with increased cardiovascular risk 2
• Consider screening for insulin resistance if metabolic abnormalities are present 2
• Baseline assessment allows for personalized risk evaluation before initiating therapy 1