What laboratory tests are recommended for the evaluation of gynecomastia?

Laboratory Tests for Gynecomastia Evaluation

For patients with gynecomastia, a comprehensive laboratory evaluation should include testosterone, estradiol, sex hormone-binding globulin (SHBG), luteinizing hormone (LH), follicular stimulating hormone (FSH), thyroid stimulating hormone (TSH), prolactin, human chorionic gonadotropin (hCG), alpha-fetoprotein (AFP), and liver and renal function tests. 1

Initial Assessment and Diagnostic Algorithm

1. Confirm true gynecomastia:

   • Distinguish from pseudogynecomastia (fatty tissue deposition) through physical examination
   • True gynecomastia presents as firm or rubbery glandular tissue directly beneath the nipple

2. Laboratory evaluation:

   • First-line tests:
     • Testosterone (T)
     • Estradiol (E2)
     • Sex hormone-binding globulin (SHBG)
     • Luteinizing hormone (LH)
     • Follicular stimulating hormone (FSH)
     • Thyroid stimulating hormone (TSH)
     • Prolactin
     • Human chorionic gonadotropin (hCG)
     • Alpha-fetoprotein (AFP)
     • Liver function tests
     • Renal function tests

3. Additional evaluation:

   • Testicular ultrasound (recommended due to low sensitivity of physical examination for detecting testicular tumors) 1
   • Breast imaging only when clinical examination is equivocal 1
   • Core needle biopsy if suspicious for malignancy 1

Age-Specific Considerations

• Neonates and pubertal boys: Laboratory testing generally not required as gynecomastia is typically physiologic and self-resolving 1

• Adults: Complete laboratory evaluation recommended as underlying pathology may be present in 45-50% of cases 1, 2

• Elderly men: Consider full evaluation despite higher prevalence of benign gynecomastia to rule out malignancy 3

Interpretation of Laboratory Results

• Elevated hCG/AFP: May indicate testicular tumor
• Low testosterone with elevated LH/FSH: Primary hypogonadism
• Low testosterone with low/normal LH/FSH: Secondary hypogonadism
• Elevated estradiol: Possible estrogen-producing tumor
• Elevated liver enzymes: May indicate liver disease affecting hormone metabolism
• Elevated TSH: Hypothyroidism
• Elevated prolactin: Hyperprolactinemia

Common Pitfalls to Avoid

1. Assuming all gynecomastia is physiologic: Even when medication use is identified as a potential cause, a complete evaluation is still warranted 1

2. Missing testicular pathology: Physical examination alone has low sensitivity for detecting testicular tumors; ultrasound is recommended 1

3. Overreliance on breast imaging: While useful in equivocal cases, clinical examination is usually sufficient for diagnosis 4, 1

4. Neglecting laboratory evaluation in elderly men: Despite higher prevalence of benign gynecomastia in this population, underlying pathology should still be considered 3

5. Inappropriate interpretation of hormone levels in adolescents: Reference ranges differ in this population, making interpretation more challenging 5

By following this structured approach to laboratory evaluation, clinicians can effectively identify underlying causes of gynecomastia and develop appropriate management strategies.