What causes gynecomastia in boys

What is Gynecomastia?

Gynecomastia refers to the enlargement of breast tissue in males. It's a common condition, particularly during puberty, and is usually temporary. The enlargement is due to an increase in glandular tissue, not just fat, which distinguishes it from pseudogynecomastia (fatty breast tissue).

Common Causes in Boys and Adolescents

The primary driver behind gynecomastia in boys is an imbalance in sex hormones, specifically a relative excess of estrogen compared to testosterone. During certain life stages, this imbalance is considered normal:

Puberty

Puberty is the most frequent time for boys to develop gynecomastia. Between the ages of 10 and 14, testosterone levels naturally rise, but estrogen levels can also increase. This temporary hormonal shift can lead to the development of breast tissue. This condition is often referred to as "pubertal gynecomastia" and typically resolves on its own within six months to two years as hormone levels stabilize. It's estimated that between 50% and 60% of adolescent boys will experience some degree of gynecomastia during puberty.

Infancy

Newborn boys can also experience temporary breast enlargement due to the passage of maternal estrogen across the placenta. This usually disappears within the first few weeks of life.

Aging

As men age, testosterone levels tend to decrease while estrogen levels may remain the same or increase relatively. This can lead to gynecomastia in older men, though it's less common in boys.

Other Contributing Factors

While hormonal changes are the main culprit, several other factors can contribute to or cause gynecomastia:

Medications

A wide range of medications can interfere with hormone balance and lead to gynecomastia. These include:

• Anti-androgens (used to treat prostate cancer or enlarged prostate)
• Anabolic steroids (often misused by athletes)
• Certain heart medications (e.g., calcium channel blockers, ACE inhibitors)
• Antidepressants and anti-anxiety medications
• Ulcer medications (e.g., H2 blockers)
• Chemotherapy drugs
• Drugs used to treat HIV/AIDS

It's crucial for boys and their parents to discuss any new medications with a doctor to understand potential side effects.

Medical Conditions

Certain underlying health issues can disrupt hormone balance and cause gynecomastia:

• Kidney failure: Impaired kidney function can affect hormone metabolism.
• Liver disease: Conditions like cirrhosis can lead to decreased breakdown of estrogen.
• Thyroid problems: Both hyperthyroidism (overactive thyroid) and hypothyroidism (underactive thyroid) can play a role.
• Tumors: In rare cases, tumors of the adrenal glands or testes can produce estrogen or substances that mimic estrogen.
• Malnutrition or starvation: While malnutrition can sometimes cause a decrease in testosterone, leading to a relative increase in estrogen, a subsequent refeeding process can also trigger temporary gynecomastia.

Lifestyle Factors

• Obesity: Excess body fat can lead to increased production of estrogen from adipose tissue and can also mask true gynecomastia by adding fat to the chest area (pseudogynecomastia).
• Substance Use: Alcohol, marijuana, heroin, and methadone have been linked to gynecomastia.

When to See a Doctor

While pubertal gynecomastia often resolves on its own, it's important to consult a doctor if:

• The condition persists for more than a year or two.
• Only one breast is affected.
• There is pain, tenderness, or nipple discharge.
• The enlargement is significant or causes emotional distress.

A doctor can help determine the underlying cause through a physical examination, medical history review, and possibly blood tests to check hormone levels and rule out other medical conditions.