What laboratory tests should be ordered for boys presenting with gynecomastia?

Laboratory Tests for Boys Presenting with Gynecomastia

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

Initial Assessment

Before ordering laboratory tests, it's important to:

1. Confirm true gynecomastia (glandular tissue) versus pseudogynecomastia (fatty tissue)
2. Determine onset and duration of breast enlargement
3. Assess pubertal stage and development
4. Evaluate for signs of systemic disease or undervirilization
5. Perform testicular examination (including ultrasound if needed) 1

Laboratory Testing Algorithm

First-line Laboratory Tests

• Testosterone
• Estradiol (E2)
• Luteinizing hormone (LH)
• Follicle-stimulating hormone (FSH)
• Sex hormone-binding globulin (SHBG)
• Thyroid-stimulating hormone (TSH)
• Prolactin
• Human chorionic gonadotropin (hCG)
• Alpha-fetoprotein (AFP)
• Liver function tests
• Renal function tests 1, 2

Interpretation of Key Laboratory Findings

• Elevated LH, normal FSH, very high testosterone, elevated estradiol: Consider partial androgen insensitivity syndrome (PAIS) 3
• Elevated hCG and/or AFP: Consider testicular tumor or other malignancy
• Low testosterone with elevated LH/FSH: Consider primary hypogonadism
• Low testosterone with low/normal LH/FSH: Consider secondary hypogonadism
• Elevated prolactin: Consider prolactinoma or medication effect
• Abnormal thyroid function: Consider thyroid dysfunction 2, 4

Special Considerations

Age-Related Considerations

• Neonatal gynecomastia: Usually transient, minimal workup needed
• Pubertal gynecomastia: Common (affects ~50% of mid-pubertal boys) and typically resolves within 24 months; basic workup if persistent beyond 2 years
• Adult gynecomastia: Higher likelihood of underlying pathology (~45-50% of cases); more extensive workup warranted 1

When to Consider Additional Testing

• Gynecomastia that is:
  • Rapidly progressive
  • Painful
  • Unilateral
  • Associated with other signs of endocrinopathy
  • Persistent beyond expected timeframe
  • Present in prepubertal boys 4, 5

Common Pitfalls and Caveats

1. Failure to distinguish true gynecomastia from pseudogynecomastia: True gynecomastia involves glandular tissue, while pseudogynecomastia is fatty tissue deposition 6

2. Overlooking medication causes: Always review medication history, as drugs like spironolactone and 5-α reductase inhibitors are well-documented causes of gynecomastia 6

3. Misinterpreting laboratory values in adolescents: Hormone levels during puberty can be difficult to interpret due to normal fluctuations 5

4. Unnecessary imaging: Most cases can be diagnosed based on clinical findings and laboratory tests; imaging should be reserved for equivocal cases 1

5. Missing testicular pathology: Always include testicular examination and consider ultrasound, as palpation alone has low sensitivity for detecting testicular tumors 1

Remember that while pubertal gynecomastia is common and typically benign, persistent cases warrant thorough evaluation to rule out underlying pathologies that may require specific treatment.