Physical Examination Findings in Secondary Hypogonadism
Gynecomastia is uncommon in secondary hypogonadism and, when present, should prompt measurement of serum estradiol and referral to endocrinology, as it suggests an alternative diagnosis or complicating factor rather than being a typical feature of the condition. 1
Expected Physical Examination Findings
Body Composition and Anthropometric Changes
- Increased body mass index (BMI) and waist circumference are commonly observed, as secondary hypogonadism is frequently associated with obesity and metabolic syndrome 2
- Decreased lean body mass and increased fat mass, particularly central adiposity, reflect the metabolic consequences of testosterone deficiency 1
Testicular Examination
- Normal to slightly reduced testicular size is typical, as the testes retain some baseline function despite inadequate gonadotropin stimulation 3, 4
- This contrasts with primary hypogonadism, where testicular atrophy is more pronounced due to intrinsic testicular failure 5
Secondary Sexual Characteristics
- Reduced body and facial hair growth may be present, depending on the severity and duration of testosterone deficiency 4
- Decreased muscle mass and strength are common findings on physical examination 1
Skin and Hair Changes
- Fine wrinkles and decreased skin thickness may be observed in chronic cases 4
- Reduced sebaceous gland activity leading to dry skin can occur 4
Gynecomastia: An Uncommon Finding Requiring Investigation
Why Gynecomastia is Atypical in Secondary Hypogonadism
- In secondary hypogonadism, both testosterone AND estradiol production are typically reduced because the low LH/FSH levels fail to stimulate the testes adequately 3
- Gynecomastia develops when the estrogen-to-androgen ratio is elevated, which is not the typical hormonal pattern in secondary hypogonadism 6
When Gynecomastia Occurs: Alternative Diagnoses to Consider
- Hyperprolactinemia should be ruled out, as elevated prolactin can cause both secondary hypogonadism AND gynecomastia through increased aromatase activity 1, 2
- Medications with antiestrogenic or antiandrogen activity (such as spironolactone, cimetidine, or antiandrogens) can cause gynecomastia independent of the hypogonadism 7
- Rare enzymatic defects such as late-onset 17-ketosteroid reductase deficiency can present with both hypogonadism and gynecomastia due to elevated androstenedione and estrone levels 6
- Functional hypogonadism with preserved aromatase activity in adipose tissue may occasionally produce enough estrogen to cause gynecomastia, particularly in obese patients 2, 8
Mandatory Workup When Gynecomastia is Present
- Measure serum estradiol prior to commencing testosterone therapy in any patient presenting with breast symptoms or gynecomastia 1
- Measure serum prolactin if LH levels are low or low-normal, as hyperprolactinemia is a treatable cause 1, 2
- Refer to endocrinology if estradiol is elevated at baseline, as this suggests an alternative diagnosis requiring specialized evaluation 1
Critical Pitfall to Avoid
Do not assume gynecomastia is a typical feature of secondary hypogonadism. Its presence should trigger investigation for hyperprolactinemia, medication effects, or rare enzymatic disorders rather than being dismissed as part of the hypogonadal syndrome 1, 6. The low gonadotropin state in secondary hypogonadism typically results in low estrogen production, making gynecomastia an unexpected finding that warrants explanation 3.