Androgenic Alopecia

See Also

Alopecia

Definitions

Androgenic Alopecia (Male-patterned Baldness)
1. Non-scarring androgen related Alopecia

Epidemiology

Most common type of Alopecia (esp. white men)
Hereditary trait (positive Family History)
Increasing Incidence with age
1. Affects white men 30% at age 30, 40% at age 40, 50% at age 50 years
2. Affects up to 38% of women over age 70 years

Course

Hair Loss onset between ages 12 to 40 years
Hair Loss evident by age 50 in >50% of patients

Pathophysiology

Androgen exposure shortens Hair FollicleAnagen phase
1. Men with increased androgen levels
2. Women with increased 5a-reductase, androgen receptors
Affected Hair Follicles transition to vellus follicles
1. Hair becomes shorter, finer, and less pigmented
Progresses with each successive cycle
Related to higher Dihydrotestosterone (DHT) levels
1. Testosterone is converted to Dihydrotestosterone (DHT) by the enzyme 5 alpha-reductase (5AR)
2. Hair Follicles transition from terminal follicles to vellus follicles in response to DHT receptor binding
  1. Androgen receptor density and 5AR activity are increased in genetically predisposed patients

Symptoms

Gradual progression of Hair Loss

Signs

General
1. Hair Follicles in affected regions are vellus follicles, appearing miniaturized
Men (M-Type distribution)
1. Hair Loss affecting temples (bitemporal), frontal forehead and crown (vertex)
2. Sides and back are spared
Women
1. Central and vertex scalp thinning
2. Temples and frontal scalp are spared unlike the M-Type found in men

Differential Diagnosis

Grading
Rating of Hair Loss (Norwood and Hamilton Scale)

Type I: Minimal hair line recession
Type II: Symmetrical triangular Hair Loss over temples
Type III: More Hair Loss at vertex and less at temple
Type IV-V: Temple and vertex Hair Loss; some crown loss
Type VI: Contiguous frontal, vertex, and crown baldness
Type VII: Hair remains only over ears and occiput
References
1. Hamilton (1951) Ann NY Acad Dermatol 53:708-28
2. Norwood (1975) South Med J 68(11):1359-65 [PubMed]

Labs
Women with Androgenetic Alopecia

Indications (Not required in most cases)
1. Irregular Menses
2. Sudden Hair Loss
3. Hirsutism
4. New onset Acne Vulgaris
5. Infertility
Lab tests
1. Total Testosterone
2. Free Testosterone
3. Dehydroepiandrosterone sulfate (DHEA-S)
4. Prolactin

Management

Precautions
1. Medications used for Alopecia are continued indefinitely
  1. Hair Loss recurrs (back to baseline) with medication discontinuation
2. If patients desire treatment, start medications at the first signs of baldness for best effect
  1. Medications are only modestly effective
Medications for Women
1. Avoid all Hair Loss medications during pregnancy
2. Topical Minoxidil (Rogaine, Hers) 2%
  1. Preferred first line agent in female pattern Hair Loss
  2. Apply 2% solution topically twice daily (or 5% foam once daily) to dry scalp (not hair)
  3. Risk of Hypertrichosis of the face
  4. Expect initial hair shedding on starting
  5. Expect 4 months to see any benefit (and 12 months to see full effect)
  6. Retin-A may augment effect (experimental)
    1. Apply at different time of day
3. Oral Contraceptives
  1. Less effective than Minoxidil
  2. Choose OCP with low Progestin Androgenic Activity
    1. Norgestimate (e.g. Ortho Tri-Cyclen)
    2. Norethindrone (e.g. Modicon)
4. Spironolactone
  1. Variable efficacy - results in modest reduction in Hair Loss
  2. Dose: 100 to 200 mg orally daily in divided doses
5. Flutamide (Eulexin)
  1. Dose: 250 mg orally daily
  2. Liver function abnormalities occur in up to one third of patients
6. Avoid agents without efficacy in women
  1. Finasteride is ineffective in women
  2. Supplements (e.g. Nutrafol, Viviscal, Biotin, Collagen, zinc) lack evidence to support their use
Medications for Men
1. Finasteride (Propecia)
  1. Dose: 1 mg orally daily
    1. Consider prescribing one quarter tablet daily of the 5 mg tablet (generic, cheap)
  2. 5-alpha reductase inhibitor indicated for men only, and if Topical Minoxidil ineffective
  3. Oral preparation for vertex or frontal balding
  4. Modifies serum PSA levels (upper limit of normal may be twice that of those not on Finasteride)
  5. Caution patients regarding risk of Suicidal Ideation, Sexual Dysfunction with Finasteride
  6. May help detect high grade Prostate Cancers earlier
    1. Thompson (2003) N Engl J Med 349:215-24 [PubMed]
2. Minoxidil (Rogaine) 2% solution or 5% foam
  1. Most effective for vertex balding (than in frontal area), and effects are delayed 6-12 months
  2. Applied topically (1 ml) twice daily to dry scalp
  3. Expect initial hair shedding on starting
3. Ketoconazole 2% Shampoo (Nizoral)
  1. Shampoo 2-4 times weekly
  2. Unknown efficacy and not FDA approved for Androgenetic Alopecia
4. Pyrithione Zinc (1%)
  1. Shampoo 2-4 times weekly
  2. Unknown efficacy and not FDA approved for Androgenetic Alopecia
Hair Transplant
1. Looks better in photos
2. Better in curly haired persons
Laser devices (Restore Caps, HairMax Combs)
1. Marginally effective at slowing Hair Loss and promoting Hair Growth
Platelet Rich Plasma Injection
1. Improves hair density in men better than Minoxidil, Finasteride and Bimatroprost
2. Less effective than low level laser therapy
3. No reported serious adverse events
4. Georgiadis (2022) am fam Physician 105(1): 84-5 [PubMed]
Avoid ineffective or unproven measures
1. Avoid topical oils
2. Avoid oral supplements for Alopecia (Biotin, keratin, Saw Palmetto, zinc)

References

(2021) Presc Lett 28(11): 65
(2023) Presc Lett 30(3): 18
Drake (1996) J Am Acad Dermatol 35:465-9 [PubMed]
Phillips (2017) Am Fam Physician 96(6): 371-8 [PubMed]
Scow (1999) Am Fam Physician, 59(8):2189-94 [PubMed]
Springer (2003) Am Fam Physician 68(1):93-102 [PubMed]