Gynecomastia is diagnosed through a combination of a physical breast exam, blood tests to check hormone levels, and sometimes imaging like mammography. The process starts with your doctor feeling for a specific type of tissue beneath the nipple: glandular breast tissue larger than 0.5 cm in diameter confirms the diagnosis. From there, the goal shifts to figuring out the cause and ruling out anything more serious.
The Physical Exam
The first and most important step is a hands-on examination. Your doctor will have you lie on your back with your hands behind your head. They’ll place a thumb on each side of the breast and slowly bring them together toward the nipple. In true gynecomastia, they’ll feel a firm, rubbery ridge of glandular tissue that sits symmetrically around the nipple-areolar complex. This tissue feels distinctly different from the soft, fatty tissue found in pseudogynecomastia (sometimes called “false” gynecomastia), where the thumbs slide together without hitting a defined ridge until they reach the nipple itself.
This distinction matters because pseudogynecomastia is simply excess fat in the chest area, often linked to higher body weight, and doesn’t involve actual breast gland growth. The two conditions look similar from the outside but require different approaches. A large cross-sectional study of over 530,000 adolescent boys found that among those diagnosed with gynecomastia, 70% had a BMI of 25 or below, suggesting the majority of true gynecomastia cases aren’t explained by excess body fat alone.
What Your Doctor Checks For During the Exam
Beyond confirming glandular tissue, your doctor is looking for warning signs that point to something other than benign gynecomastia. They’ll note whether the tissue is centered under the nipple or off to one side. Gynecomastia almost always sits symmetrically beneath the areola. A lump that’s hard, fixed in place, or positioned away from the center of the nipple raises concern for a possible tumor and warrants further testing.
Other red flags include skin changes over the breast (dimpling, puckering, or thickening), nipple discharge (especially if bloody), crusting or scaling of the nipple skin, and swelling or redness that makes the breast feel warm or tender. Paget disease of the nipple, a rare form of breast cancer, can cause the nipple skin to look scaly, red, and irritated with areas of itching or bleeding. Male breast cancer is uncommon, but both gynecomastia and breast cancer can feel like a growth under the nipple, which is why any new lump should be evaluated.
Blood Tests and Hormone Panels
Once the physical exam confirms breast gland enlargement, blood work helps identify the underlying cause. The standard panel includes free or total testosterone, estradiol (the primary form of estrogen), luteinizing hormone (LH), and DHEA-S (a hormone produced by the adrenal glands). Together, these reveal whether a hormonal imbalance is driving the breast tissue growth.
Low testosterone with elevated estradiol is a common pattern. LH levels help pinpoint where the problem originates: high LH suggests the testicles aren’t producing enough testosterone despite the brain signaling them to do so, while low LH can indicate a problem with the pituitary gland or hypothalamus. If your doctor suspects an overactive thyroid, they’ll add thyroid-stimulating hormone (TSH) and free thyroxine to the panel, since hyperthyroidism can trigger gynecomastia by increasing the body’s conversion of testosterone to estrogen.
Your doctor will also review your medications. A long list of drugs can cause gynecomastia, including certain heartburn medications, anti-anxiety drugs, heart medications, and anabolic steroids. In many cases, a medication change resolves the issue without further workup.
When Imaging Is Needed
Not every case of gynecomastia requires imaging. If the physical exam clearly identifies symmetrical, soft glandular tissue in an otherwise healthy person, imaging may be unnecessary. But when something looks or feels atypical, your doctor will order additional tests.
Mammography is the primary imaging tool for evaluating male breast tissue. A study examining 360 men with breast symptoms found that mammography detected all 15 cancers in the group. Ultrasound was performed on 278 of those cases afterward and found zero additional cancers. The researchers concluded that ultrasound added no meaningful diagnostic value when mammography was already negative. In practice, if a mammogram comes back normal or shows a benign pattern, most doctors won’t follow up with ultrasound.
Testicular ultrasound is a separate consideration. If blood work shows elevated estradiol levels and the physical exam raises any suspicion of a testicular mass, your doctor will order an ultrasound of the testicles. Certain testicular tumors produce hormones that stimulate breast tissue growth, and catching them early is critical.
Grading the Severity
Once gynecomastia is confirmed, doctors often classify it by grade. The grading system adapted from the McKinney, Simon, Hoffman, and Kohn scales, used by the American Society of Plastic Surgeons, breaks it into three levels:
- Grade I: Small enlargement with a localized button of tissue concentrated around the areola.
- Grade II: Moderate enlargement that extends beyond the areola boundaries, with edges that blend into the surrounding chest.
- Grade III: Moderate to significant enlargement beyond the areola with distinct edges and excess skin.
Grading helps guide treatment decisions. Grade I gynecomastia may resolve on its own, especially in adolescents, and often needs only monitoring. Higher grades with excess skin are more likely to require surgical correction if treatment is desired. The grading also plays a role in insurance coverage decisions, since many insurers require documentation of a specific grade before approving surgery.
Age and Context Shape the Diagnosis
Gynecomastia has three natural peaks across a lifetime: the newborn period, puberty, and older age. In adolescents, it most commonly appears between ages 13 and 14, with nearly 39% of cases diagnosed at age 13 and about 33% at age 14 in a large population study. Most pubertal gynecomastia resolves within one to two years without treatment, so doctors often take a watchful-waiting approach rather than jumping to extensive testing in an otherwise healthy teenager.
In older adults, the workup tends to be more thorough because the list of potential causes broadens. Declining testosterone, increased body fat (which converts testosterone to estrogen), chronic liver or kidney disease, and a growing number of medications all become more relevant. The same physical exam and blood panel apply, but the threshold for ordering imaging is typically lower in older men, particularly when the onset is recent, one-sided, or rapidly progressing.
For men of any age, gynecomastia that appears suddenly, grows quickly, or is accompanied by pain, nipple discharge, or a hard irregular mass calls for prompt evaluation rather than a wait-and-see approach.