Androgenetic alopecia

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Androgenetic alopecia is a common form of hair loss in both men and women. In men, it is also known as male pattern baldness, and in women, it is also known as female pattern hair loss.

In men, hair is lost in a well-defined pattern, beginning above both temples. Over time, the hairline moves back (recedes) to form a characteristic "M" shape. Hair also thins at the top of the head (vertex or crown), often progressing to partial or complete baldness.

The pattern of hair loss in women differs from male-pattern baldness. In women, the hair becomes thinner at the top of the head, and the middle part widens. The hairline does not typically recede. Androgenetic alopecia in women rarely leads to total baldness.

Androgenetic alopecia in men has been associated with several other medical conditions, including coronary heart disease and enlargement of the prostate. Additionally, prostate cancer, disorders of insulin resistance (such as diabetes and obesity), and high blood pressure (hypertension) have been related to androgenetic alopecia.

In women, this form of hair loss is associated with an increased risk of polycystic ovary syndrome (PCOS). PCOS is characterized by a hormonal imbalance that can lead to irregular menstruation, acne, excess hair elsewhere on the body (hirsutism), and weight gain.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

A variety of genetic and environmental factors likely play a role in causing androgenetic alopecia. Although researchers are studying risk factors that may contribute to this condition, most of these factors remain unknown. Researchers have determined that this form of hair loss, particularly in men, is related to hormones called androgens, specifically an androgen called dihydrotestosterone (DHT). Androgens play a role in female pattern hair loss, but other factors that are not yet known are also involved.

Androgens are important for normal male sexual development before birth and during puberty. Androgens also have other important functions in both males and females, such as regulating hair growth and sex drive.

Hair growth begins under the skin in structures called follicles. Each strand of hair normally grows for 2 to 6 years, goes into a resting phase for several months, and then falls out. The cycle starts over when the follicle begins growing a new hair.

Androgens help control this cycle. However, too much stimulation of hair follicles by androgens may lead to a shorter growth period, resulting in shorter and thinner strands of hair. The growth of new hair to replace strands that are shed is also delayed. Together, these changes lead to hair thinning or loss.

Researchers suspect that variants (also called mutations) in several genes play a role in androgenetic alopecia. However, scientific studies have confirmed only that variations in one gene, the AR gene, are involved in this condition. The AR gene provides instructions for making a protein called an androgen receptor. Androgen receptors allow the body to respond appropriately to DHT and other androgens. Studies suggest that variations in the AR gene result in androgen receptors that are more easily stimulated by androgens than normal, leading to increased activity of the receptors in hair follicles. It remains unclear, however, how these genetic changes increase the risk of hair loss in men and women with androgenetic alopecia.

Researchers continue to investigate the connection between androgenetic alopecia and other medical conditions, such as coronary heart disease and prostate cancer in men and polycystic ovary syndrome in women. They believe that some of these disorders may be associated with elevated androgen levels, which may help explain why they tend to occur with androgen-related hair loss.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

The inheritance pattern of androgenetic alopecia is unclear, because many genetic and environmental factors are likely to be involved. This condition tends to cluster in families, however, and having a close relative with patterned hair loss appears to be a risk factor for developing the condition.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Androgenetic alopecia affects an estimated 50 million men and 30 million women in the United States. Androgenetic alopecia can start as early as a person's teens, and the risk increases with age; more than 50 percent of men over age 50 have some degree of hair loss. In women, hair loss is most likely after menopause.

Which doctor should you see?

The suggested department for discussing Androgenetic alopecia is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Androgenetic alopecia. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.