Overview of Androgenetic Alopecia

Androgenetic alopecia is an androgen-dependent hereditary disorder characterized by the progressive transformation of terminal hairs into indeterminate hairs, and then vellus hairs. The inheritance is polygenic, with genetic input from either or both parents. It is a highly prevalent disease that affects both men and women, resulting in male pattern hair loss (MPHL) and female pattern hair loss (FPHL).

Etiology of MPHL

MPHL is the most prevalent form of diffuse hair thinning and baldness in adult males. It is caused by a genetically determined sensitivity to the effects of dihydrotestosterone (DHT), which is regulated by the enzyme 5-alpha reductase. DHT is thought to shorten the anagen (growth) phase of the hair cycle; together with the miniaturization of the follicles, resulting in progressively thinner and fewer hairs.

Presentation of MPHL

MPHL presentation patterns can be classified using the Norwood-Hamilton scale. It is characterized by frontoparietal and frontal hairline recession and vertex thinning, which then progresses into a bald patch on top of the head.

Treatment of MPHL

Minoxidil solution and finasteride tablets are FDA approved medications for the treatment of MPHL. Hair transplantation is a surgical option that is used for the treatment. Platelet-rich plasma injections and lesser therapy are alternative therapies under investigation. Finasteride has shown to be effective in managing MPHL. It works by blocking the enzyme type II 5a-reductase activity and reducing the production of DHT.

Etiology of FPHL

FPHL is a distinct type of diffuse female hair loss. It is presently unknown whether androgens play a role in FPHL, whereas their role in male pattern baldness is clear. The vast majority of women with FPHL have normal blood levels of androgens.

Presentation of FPHL

FPHL is characterized by diffuse central thinning of the crown with preservation of the frontal hairline. The severity of FPHL can be assessed using the Ludwig scale according to the central part width. FPHL is frequently confused with a condition known as chronic telogen effluvium, as both conditions cause excessive hair loss.

Treatment of FPHL

Minoxidil solution is approved for the management of FPHL. In cases with hyperandrogenemia, other medications that suppress androgen can be added, such as oral contraceptives, spironolactone, or finasteride. Hair transplantation can also be offered to women with severe FPHL.

Burden of Androgenetic Alopecia

Numerous studies have demonstrated that hair loss is not merely a cosmetic issue, but also a major source of emotional distress. Studies indicate that hair loss is associated with sentiments of low self-esteem, depression, introversion, and unattractiveness.

Written by

Mohammed Alahmadi, Medical Student

Revised by

Maee Barakeh, medical student

References

DermNet

Medscape

Bolognia textbook of dermatology