Blood Investigations for Male Gynecomastia
A comprehensive hormonal and biochemical panel should be obtained in all adult men presenting with gynecomastia to identify underlying pathology, which is present in approximately 45-50% of cases. 1
Essential Laboratory Tests
The following blood investigations form the core diagnostic workup for gynecomastia 1, 2:
Primary Hormonal Panel
- Testosterone (total): Assess for hypogonadism and androgen deficiency 1, 2
- Estradiol (E2): Evaluate for elevated estrogen levels contributing to hormonal imbalance 1, 2
- Sex hormone-binding globulin (SHBG): Calculate free testosterone and assess hormone bioavailability 1
- Luteinizing hormone (LH): Differentiate primary from secondary hypogonadism 1, 2
- Follicle-stimulating hormone (FSH): Further characterize gonadal function when indicated 1, 2
Tumor Markers (Critical for Malignancy Screening)
- Human chorionic gonadotropin (hCG): Screen for testicular germ cell tumors, which can present with gynecomastia 1, 2
- Alpha-fetoprotein (AFP): Additional tumor marker for testicular malignancies 1, 2
Additional Endocrine Evaluation
- Prolactin: Identify hyperprolactinemia and potential pituitary pathology 1, 2
- Thyroid-stimulating hormone (TSH): Rule out thyroid dysfunction as an underlying cause 1, 2
- Free T4 (fT4): When TSH is abnormal, further characterize thyroid status 2
Organ Function Assessment
- Liver function tests: Detect chronic liver disease, which commonly causes gynecomastia through altered hormone metabolism 1, 2
- Renal function tests: Assess kidney function, as renal disease can contribute to hormonal imbalances 1, 2
Age-Specific Considerations
Pubertal Gynecomastia (Adolescents)
- Minimal laboratory workup is typically needed, as pubertal gynecomastia affects approximately 50% of mid-pubertal boys and resolves spontaneously in over 90% within 24 months 1
- Blood investigations are only warranted if clinical features suggest underlying pathology 1
Adult-Onset Gynecomastia (≥18 years)
- Complete laboratory evaluation is essential, as underlying pathology is identified in 43% of cases with adult onset 3
- The comprehensive panel listed above should be obtained routinely 1, 2
Additional Tests When Clinically Indicated
Based on initial findings or clinical suspicion, consider 2:
- Dehydroepiandrosterone (DHEA): When adrenal pathology is suspected
- Free testosterone (fT): For more precise assessment of androgen status
- Chromosomal analysis: If Klinefelter syndrome is suspected (especially with small, firm testes and elevated FSH/LH)
Clinical Context and Pitfalls
The presence of an apparent cause (such as medication use) should not preclude detailed investigation, as multiple factors may coexist 1. Even when a reversible cause like drug-induced gynecomastia is identified, the full hormonal panel helps exclude concurrent pathology 1.
Testicular ultrasound should accompany blood work, as physical examination alone has low sensitivity for detecting testicular tumors that may present with gynecomastia 1. This imaging is particularly important given that hCG-secreting tumors are a critical differential diagnosis 1, 2.
The laboratory evaluation should be interpreted alongside a thorough medication history (including supplements and recreational drugs), assessment of virilization status, and examination for signs of systemic disease 1. Approximately 45-50% of adult cases will reveal treatable underlying pathology when properly investigated 1, 3.