Male pattern hair loss (androgenetic alopecia, balding)

Cause:

• Inherited condition due to genetically determined sensitivity to dihydrotestosterone (DHT).

DHT Effects:

• Shortens the anagen phase of hair growth from 3–6 years to weeks/months.
• Causes follicle miniaturization.

5-Alpha Reductase:

• Enzyme that regulates DHT production.

Genetics:

• Multiple genes involved, inherited from both parents.
• Affects onset, progression, pattern, and severity of hair loss.
• Sons have 5-6 times higher risk if their fathers were balding.

Genetic Testing:

• Currently unreliable for predicting balding.

Women with Male Pattern Hair Loss (MPHL)

Characteristics:

• Often have excessive androgens and genetic predisposition.
• Linked with polycystic ovarian syndrome (PCOS) which includes symptoms like acne, irregular menses, and excessive facial/body hair.
• May also be associated with congenital adrenal hyperplasia.

Female Pattern Hair Loss

Prevalence:

• More common in aging women.
• Typically have normal hormone tests.

Prevalence of Male Pattern Baldness

General Prevalence:

• Affects nearly all men at some point in their lives.
• Varies by population, likely due to genetic factors.

Specific Statistics:

• Up to 50% of male Caucasians experience some degree of hair loss by age 50.
• Approximately 80% of male Caucasians experience hair loss by age 70.
• Japanese and Chinese men are less affected compared to Caucasians.

Pathophysiology

Role of Androgens:

• Essential for the development of alopecia.
• Absent in males castrated before puberty or with androgen insensitivity.
• Androgen receptor activation shortens the anagen phase, leading to hair follicle miniaturization.
• Patients show higher levels of dihydrotestosterone (DHT) and more androgen receptors in balding areas.

Normal Hair Growth Cycle

Anagen Phase (Growth Phase):

• Duration: 2–6 years
• Characteristics: Follicle is long and deep, producing thick, well-pigmented hair.
• Prevalence: About 90% of scalp hairs.

Catagen Phase (Transition Phase):

• Duration: 1–2 weeks
• Characteristics: Base of the follicle shrivels.

Telogen Phase (Resting Phase):

• Duration: 3 months
• Characteristics: Shrunken follicle retains hair fiber, old hair falls out as new hair begins to grow.

Hair Miniaturization

• Tufts: Scalp hairs grow in tufts of 3–4.
• Androgenetic Alopecia: Progressive loss of hairs in the tufts, leading to bald scalp areas.

DHT in the Body

• Presence: Found in the prostate gland and skin.

Role of 5-Alpha Reductase

• Function: Enzyme that regulates DHT production, acting as a catalyst in chemical reactions.
• Inhibition: Can be inhibited by specially synthesized drugs.

History and Physical:

typically starts with receding hairline(Begins as bitemporal thinning, then involves vertex.) and bald patch (vertex)

Psychological Impact

• Male pattern hair loss can negatively impact psychological well-being.
• Associated with low self-esteem, depression, introversion, and feelings of unattractiveness.
• Societal attitudes, particularly in Western cultures, emphasize youthful appearance and attractiveness.
• Studies indicate men with hair loss may be perceived as less attractive, less assertive, less likeable, and less successful than men without hair loss.

Evaluation:

• Diagnosed clinically with gradual onset after puberty.
• Gradual Thinning of Hair: Begins at the temples and crown.
• Receding Hairline: Forms an “M” shape.
• Thinning at the Crown: Progresses to bald spots.
• Eventual Baldness: May progress to complete hair loss on the top of the scalp while maintaining hair on the sides and back.

• Dermoscopy useful; biopsy rarely necessary
• Additional medical history and tests may be required to rule out other causes.
  • Thyroid studies
  • FBC
  • iron deficiency with iron, total iron binding capacity, and ferritin
  • Screen for syphilis
  • quick psychiatric screen for
    • depressive symptoms and other psychiatric disorders may also be warranted in all hair loss patients visiting a dermatologist

Treatment Options

1. Hair Replacement/Transplantation
2. Cosmetics
3. Micropigmentation (Tattoo)
   • Resembles a shaven scalp.
4. Hairpieces
5. Medications:
   • Minoxidil Solution
     • Side Effects: Scalp irritation, unwanted facial hair growth.
   • Finasteride Tablets (Type II 5-alpha-reductase inhibitor)
     • Side Effects: Sexual dysfunction (reduced libido, erectile dysfunction), gynecomastia.
   • Dutasteride

Differential Diagnosis:

• Alopecia Areata
• Anagen effluvium
• Syphilis
• Systemic diseases
• Telogen effluvium

Pearls and Other Issues:

• Association with cardiovascular diseases, prostate cancer, colon cancer, and urolithiasis.
• Poor cosmesis is a common issue for patients.
• Increased risk of actinic keratosis and adverse cardiac events in males, link to polycystic ovarian disease in females.