From the Guidelines
Gynecomastia in men is primarily caused by an imbalance between estrogen and testosterone hormones, leading to enlarged breast tissue, and can result from various factors including hormonal changes, certain medications, health conditions, and substance use. This condition can be triggered by hormonal changes during puberty, aging, obesity, and certain medications such as spironolactone, ketoconazole, cimetidine, finasteride, certain antipsychotics, and some HIV medications 1. Health conditions like liver disease, kidney failure, hyperthyroidism, and certain tumors can also contribute to gynecomastia, as well as substance use, particularly anabolic steroids, marijuana, alcohol, and heroin 1.
The underlying mechanism involves increased estrogen activity or decreased testosterone effect, disrupting the normal hormone balance. Excess fat tissue in obesity converts testosterone to estrogen, while aging naturally decreases testosterone levels 1. In many cases, especially during puberty, gynecomastia resolves on its own, but persistent cases may require addressing the underlying cause or medical intervention. According to the American College of Radiology, gynecomastia is the most common cause of a palpable mass, breast enlargement, or pain in men, and is often bilateral, presenting as a soft, rubbery, or firm mobile mass directly under the nipple 1.
Key factors that contribute to gynecomastia include:
- Hormonal changes during puberty, aging, and obesity
- Certain medications, such as spironolactone, ketoconazole, and finasteride
- Health conditions, including liver disease, kidney failure, and hyperthyroidism
- Substance use, particularly anabolic steroids and marijuana
- Excess fat tissue in obesity, which converts testosterone to estrogen
- Aging, which naturally decreases testosterone levels 1.
It is essential to identify the underlying cause of gynecomastia to provide appropriate treatment and prevent potential complications. If the differentiation between benign disease and breast cancer cannot be made on the basis of clinical findings, or if the clinical presentation is suspicious, imaging is indicated, with ultrasound recommended for men younger than 25 and mammography or digital breast tomosynthesis for men 25 and older 1.
From the FDA Drug Label
Spironolactone can cause gynecomastia. In a Randomized Spironolactone Evaluation Study, patients with heart failure treated with a mean dose of 26 mg of spironolactone once daily, about 9% of the male subjects developed gynecomastia. The risk of gynecomastia increases in a dose-dependent manner with an onset that varies widely from 1 to 2 months to over a year. Gynecomastia is usually reversible. Gynecomastia has been reported in patients treated for one month or longer. In patients being treated for pathological hypersecretory states, this occurred in about 4% of cases while in all others the incidence was 0. 3% to 1% in various studies.
Gynecomastia in men can be caused by certain medications, including:
- Spironolactone 2: The risk of gynecomastia increases in a dose-dependent manner.
- Cimetidine 3: Gynecomastia has been reported in patients treated for one month or longer, with an incidence of about 4% in patients with pathological hypersecretory states and 0.3% to 1% in other cases.
From the Research
Causes of Gynecomastia
- Gynecomastia is a benign proliferation of glandular tissue of the breast in men, caused by an imbalance between estrogen and androgen action at the level of breast tissue 4, 5, 6, 7
- It can be caused by various factors, including:
- Physiological conditions, such as neonatal period, puberty, and senescence 5, 7
- Hormonal imbalances, such as estrogen excess and/or androgen deficiency 4, 6, 7
- Certain medications, which can cause hypogonadism, anti-androgenic effects, and hyperprolactinemia 8
- Underlying medical conditions, such as liver failure and chronic kidney disease 7
- Idiopathic causes, where the underlying cause is unknown 6
Risk Factors
- Age: Gynecomastia is common in adolescents and adults, and its prevalence increases with age 4, 5
- Medications: Certain medications, such as exogenous estrogens, anti-androgens, and certain antibiotics, can increase the risk of gynecomastia 8
- Hormonal imbalances: Conditions that affect hormone levels, such as hypogonadism and hyperthyroidism, can increase the risk of gynecomastia 4, 6, 7
- Family history: A family history of gynecomastia may increase the risk of developing the condition 4
Diagnosis and Treatment
- Diagnosis of gynecomastia involves a thorough medical history, physical examination, and laboratory tests to rule out underlying medical conditions and identify the underlying cause 4, 5, 6
- Treatment options for gynecomastia include:
- Watchful waiting: For mild cases of gynecomastia, where the condition may resolve on its own 4
- Medical therapy: For cases of gynecomastia caused by hormonal imbalances or certain medications, medical therapy may be effective 4, 8, 6
- Surgery: For chronic and severe cases of gynecomastia, surgical removal of the breast tissue may be necessary 4, 5, 6