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Alopecia

Definition:
Absence of hair from areas where it normally grows.

Hair Follicle Cycle Phases

  • Anagen phase: Growth phase; 90% of scalp hair follicles; lasts 2-6 years.
  • Catagen phase: Transition; follicle regression; <1% follicles; lasts 3 weeks.
  • Telogen phase: Resting phase; club hair ready for shedding; lasts 2-3 months.

Types of Alopecia

Scarring (Cicatricial) Alopecia

  • Inflammatory disorders causing permanent follicle destruction and hair loss.
  • Includes lymphocytic, neutrophilic, mixed types.
  • Primary scarring causes: discoid lupus, lichen planopilaris, frontal fibrosing alopecia, central centrifugal cicatricial alopecia (common in African American women), acne keloidalis nuchae, folliculitis decalvans, dissecting cellulitis of scalp.
  • Secondary causes: infection, neoplasm, radiation, surgery, physical trauma (e.g., tinea capitis).
  • Clinical sign: slick smooth scalp without follicles.

Nonscarring (Noncicatricial) Alopecia

  • Mild or no inflammation; follicles intact.
  • Types:
  • Focal: alopecia areata (AA), traction alopecia.
  • Patterned: androgenic alopecia, female pattern hair loss.
  • Diffuse: telogen effluvium, anagen effluvium.
  • Structural hair disorders: brittle hair from abnormal formation or external insult.

Epidemiology

  • Androgenic alopecia:
  • Males: 30% by age 30, 50% by 50, 80% by 70.
  • Females: 70% of women >65 years.
  • Alopecia areata (AA): 1/1000, lifetime risk 1-2%, equal sexes.
  • Scarring alopecia: rare, 3-7% of hair disorder patients.

Etiology and Pathophysiology

Scarring Alopecia

  • Permanent follicle destruction due to inflammation.
  • Loss of follicles, smooth scalp appearance.
  • Central centrifugal cicatricial alopecia common in African American women, possibly linked to hair care practices.

Nonscarring Alopecia

  • Alopecia areata (AA): autoimmune, T-cell mediated inflammation causing premature catagen and telogen phases.
  • May progress to alopecia totalis or universalis.
  • Nail involvement in 10-20%.
  • High psychiatric comorbidity.
  • Alopecia syphilitica: “moth-eaten” hair loss in secondary syphilis.
  • Traction alopecia: from tight braids, ponytails, weaves.
  • Androgenic alopecia: terminal hairs convert to vellus hairs.
  • Male pattern: bitemporal/vertex thinning (Hamilton-Norwood scale).
  • Female pattern: frontal/vertex thinning, possible association with PCOS, adrenal/pituitary hyperplasia.
  • Trichotillomania: hair pulling disorder, variable patterns.
  • Telogen effluvium: sudden shift of follicles from anagen to telogen phase, decreased density, triggered by stress, illness, meds, malnutrition.
  • Anagen effluvium: interruption of anagen phase without telogen transition, days to weeks after triggers like chemotherapy.
  • Structural hair disorders include inherited (e.g., Menkes disease) or acquired hair shaft abnormalities.

Risk Factors

  • Genetic predisposition.
  • Chronic illness: autoimmune disease, infections, cancer.
  • Physiologic stress: pregnancy, childbirth.
  • Poor nutrition.
  • Medications, chemotherapy, radiation.
  • Hair treatments, braids, weaves/extensions.

Diagnosis

History

  • Rate, duration, distribution of hair loss.
  • Hair care practices: heat, coloring, chemical relaxers, styling.
  • Associated symptoms: pruritus, pain, burning.
  • Medical history: illnesses, surgeries, pregnancy, thyroid disorders, iron deficiency.
  • Psychological stress.
  • Dietary history and weight changes.
  • Family history of hair loss/autoimmune disease.

Physical Exam

  • Pattern: generalized, patterned, focal.
  • Hair density, vellus vs terminal hairs, broken hairs.
  • Scalp for scaling, inflammation, papules, pustules.
  • Follicular ostia presence (helps classify alopecia).
  • Hair pull test: ≥6 hairs dislodged from 25-50 hair pull is abnormal.
  • Nail disorders, skin changes.
  • Signs of thyroid disease, lupus, virilization (acne, hirsutism, acanthosis nigricans, truncal obesity).

Differential Diagnosis

  • Determine alopecia type then reversible causes.

Diagnostic Tests & Interpretation

  • Labs may not be needed if clinical picture clear.
  • For diffuse nonscarring alopecia: TSH, serum iron/ferritin, CBC.
  • Consider LFT, BMP, zinc, RPR, ANA, prolactin based on history/exam.
  • In suspected female hyperandrogenism: free/total testosterone, DHEA-S.
  • Dermatoscopy: exclamation point hairs in AA.
  • Hair pull test supports shedding diagnosis.
  • Hair shaft microscopy differentiates anagen vs telogen hairs.
  • Biopsy:
  • Scarring alopecia: biopsy at inflamed edge.
  • Nonscarring alopecia: biopsy at thinning but not bald area.
  • Rule out tinea capitis by KOH prep and UV fluorescence.

Treatment

General Measures

  • Assess harm vs benefit.
  • Treat underlying causes (e.g., thyroid disease, syphilis).
  • Traction alopecia: behavior modification.
  • Trichotillomania: psychological intervention.

Medication

Alopecia Areata

  • Spontaneous remission rates vary by extent.
  • Children <10 years: topical 0.1% mometasone +/- 5% minoxidil BID (1)[A].
  • ≥10 years with <50% scalp involvement: topical corticosteroids +/- intralesional steroids +/- topical minoxidil (1)[C].
  • Intralesional triamcinolone 2.5 mg/mL, 0.1 mL per injection every 4-6 weeks (max 40 mg/session).
  • Side effects: itching, burning, acne, skin atrophy.

  • 50% scalp involvement: add topical immunotherapy (diphenylcyclopropenone [DPCP] or 3% squaric acid dibutyl ester [SADBE]) (1)[C].

  • JAK inhibitors (e.g., baricitinib) +/- intralesional steroids (2)[C].
  • Dose: baricitinib 2 mg daily, increase to 4 mg if no response at 3 months; discontinue if no response at 6 months.
  • Baseline labs: CBC, LFTs, lipids, hepatitis panel, latent TB, renal function, pregnancy test.

Androgenic Alopecia

  • Requires indefinite treatment.
  • Minoxidil (3)[A]: 2% solution 1 mL BID or 5% foam daily women; 5% solution or foam 1 mL BID men.
  • Side effects: skin irritation, hypertrichosis, tachycardia; Category C in pregnancy.
  • Finasteride (3)[A]: oral 1 mg daily (off-label in women).
  • Side effects: libido loss, gynecomastia, depression; contraindicated in pregnancy (Category X).
  • Spironolactone (3)[A]: 100-200 mg/day (off-label).
  • Side effects: hyperkalemia, menstrual irregularities, fatigue; Category D in pregnancy.
  • Combination therapy (finasteride + minoxidil) superior to monotherapy.

Surgery / Other Procedures

  • Cosmetic aids: wigs, hairpieces, scarves, hats.
  • Surgical: grafts, flaps, excision of scarred areas (primarily for scarring alopecia).
  • Platelet-rich plasma therapy stimulates dormant follicles.

Complementary & Alternative Medicine

  • Herbal medications available; limited evidence.
  • Volumizing shampoos may improve cosmetic appearance.

Ongoing Care

Diet

  • Supplement nutritional deficits as needed.

Patient Education

  • National Alopecia Areata Foundation: https://www.naaf.org/

Prognosis

  • Cicatricial alopecia: permanent follicle loss; prognosis depends on subtype and treatment.
  • Alopecia areata: often regrows within 1 year; recurrence common. Poor prognosis associated with long duration, extensive loss, autoimmune disease, nail involvement, young age.
  • Traction alopecia: excellent prognosis with behavior modification.
  • Androgenic alopecia: prognosis varies with treatment response.
  • Telogen effluvium: shedding peaks ~3 months after trigger; recovery in 3-6 months, cosmetically significant regrowth may take 12-18 months; rarely permanent loss with chronic illness.

References

  1. Strazzulla LC, Wang EHC, Avila L, et al. Alopecia areata: new treatments and overview of current therapies. J Am Acad Dermatol. 2018;78(1):15-24.
  2. King B, Ohyama M, Kwon O, et al; BRAVE-AA Investigators. Phase 3 trials of baricitinib for alopecia areata. N Engl J Med. 2022;386(18):1687-1699.
  3. Kanti V, Messenger A, Dobos G, et al. Evidence-based (S3) guideline for treatment of androgenetic alopecia. J Eur Acad Dermatol Venereol. 2018;32(1):11-22.

See Also

  • Hyperthyroidism
  • Lichen Planus
  • Systemic Lupus Erythematosus (SLE)
  • Polycystic Ovarian Syndrome (PCOS)
  • Syphilis
  • Tinea (Capitis, Corporis, Cruris)

ICD10 Codes

  • L65.9 Nonscarring hair loss, unspecified
  • L64.9 Androgenic alopecia, unspecified
  • L63.9 Alopecia areata, unspecified

Clinical Pearls

  • History and physical exam essential to determine alopecia type and guide treatment.
  • Treat underlying conditions or remove offending medications to resolve hair loss.
  • Patient education on condition nature and expectations is critical.
  • Alopecia may significantly impact psychological well-being; address as needed.