Overview
Alopecia
1. Overview
Alopecia is the general medical term for hair loss. It is a broad category encompassing various etiologies ranging from benign, self-limiting conditions to permanent, scarring disorders. Accurate diagnosis is critical as treatments differ fundamentally between scarring (cicatricial) and non-scarring forms.
Classification
-
Non-Scarring Alopecia (Hair follicles preserved; potential for regrowth)
- Androgenetic Alopecia: Pattern hair loss (Male/Female)
- Alopecia Areata: Autoimmune patchy loss
- Telogen Effluvium: Stress-reactive shedding
- Trichotillomania: Traumatic pulling
- Tinea Capitis: Fungal infection
-
Scarring (Cicatricial) Alopecia (Hair follicles destroyed; permanent loss)
- Lichen Planopilaris (LPP)
- Frontal Fibrosing Alopecia (FFA)
- Discoid Lupus Erythematosus (DLE)
- Folliculitis Decalvans
Key Epidemiology
| Type | Prevalence | Demographics |
|---|---|---|
| Androgenetic | >50% of men >0y | Men > Women; Age-dependent |
| Areata | 2% lifetime risk | Children & Young Adults |
| Telogen Effluvium | Common | Post-partum, Post-illness |
2. Pathophysiology
┌─────────────────────────────────────────────────────────────────────────────┐
│ ALOPECIA PATHOPHYSIOLOGY │
├─────────────────────────────────────────────────────────────────────────────┤
│ │
│ ┌─────────────────────────────────────────────────────────────────────┐ │
│ │ THE HAIR GROWTH CYCLE │ │
│ │ 1. Anagen (Growth): 2-6 years (85-90% of hairs) │ │
│ │ 2. Catagen (Transition): 2-3 weeks (<1%) │ │
│ │ 3. Telogen (Resting): 3 months (10-15%) -> Shedding (Exogen) │ │
│ └─────────────────────────────────────────────────────────────────────┘ │
│ ↓ │
│ ┌───────────────────┼────────────────────┐ │
│ ↓ ↓ ↓ │
│ ┌────────────────────┐ ┌──────────────────┐ ┌──────────────────────┐ │
│ │ ANDROGENETIC │ │ ALOPECIA AREATA │ │ TELOGEN EFFLUVIUM │ │
│ │ (Miniaturization) │ │ (Autoimmune) │ │ (Cycle Reset) │ │
│ └────────────────────┘ └──────────────────┘ └──────────────────────┘ │
│ ↓ ↓ ↓ │
│ • DHT sensitivity │ • T-cell attack on │ • Stress/Shock triggers │ │
│ • Shortened Anagen │ hair bulb │ synchronous entry │ │
│ • Follicles shrink │ • "Immune privi- │ into Telogen │ │
│ (Miniaturization) │ lege" collapse │ • Massive shedding 3 │ │
│ • Terminal -> Vellus │ • Non-scarring │ months LATER │ │
│ hairs │ │ │ │
│ │ │ │ │
└────────────────────────┴─────────────────────┴──────────────────────────────┘
Mechanisms by Type
-
Androgenetic Alopecia (AGA):
- Dihydrotestosterone (DHT) causes follicular miniaturization in genetically susceptible follicles.
- Terminal hairs (thick, pigmented) are replaced by Vellus hairs (fine, unpigmented).
-
Alopecia Areata (AA):
- CD8+ T-cells attack the hair bulb.
- Collapse of "immune privilege" of the hair follicle.
- Hairs enter dystrophic catagen/telogen state but follicles remain intact (reversible).
-
Scarring Alopecia:
- Inflammation targets the bulge region (stem cell reservoir).
- Permanent destruction of stem cells = permanent hair loss.
3. Clinical Features
History Taking
Essential Questions:
- Shedding vs Thinning? (Hairs coming out in clumps vs scalp becoming more visible?)
- Duration? (Acute <6 months vs Chronic)
- Pattern? (Patchy, diffuse, or receding hairline?)
- Triggers? (Illness, childbirth, stress 3 months ago? New medications?)
- Symptoms? (Itching, burning, pain? - Red flags for scarring)
- Hormonal signs? (Acne, hirsutism, irregular periods in women?)
Diagnosis by Pattern
| Pattern | Likely Diagnosis | Clinical Features |
|---|---|---|
| Patchy Loss | Alopecia Areata | Smooth, round patches; Exclamation mark hairs |
| Tinea Capitis | Scaly, broken hairs, inflammation (kids) | |
| Trichotillomania | Irregular borders, hairs of different lengths | |
| Diffuse Loss | Telogen Effluvium | Positive hair pull test, generalized thinning |
| Female Pattern | Widening of central part, preserved hairline | |
| Receding | Male Pattern | M-shape recession, vertex thinning |
| Frontal Fibrosing | "Band" of recession, loss of eyebrows (scarring) |
Physical Examination Tools
- Hair Pull Test: Gently pull ~60 hairs. >10% (6+ hairs) extracted = Active shedding (Telogen effluvium, active AA).
- Trichoscopy (Dermoscopy): Essential for diagnosis.
Trichoscopy Findings
| Condition | Key Findings |
|---|---|
| Alopecia Areata | Yellow dots, black dots, exclamation mark hairs |
| Androgenetic | Hair diameter diversity (thick and thin hairs mixed) |
| Lichen Planopilaris | Perifollicular scaling/erythema, loss of follicular ostia |
| Tinea Capitis | Comma hairs, corkscrew hairs |
4. Diagnosis
Diagnostic Approach
Usually clinical + trichoscopy. Biopsy reserved for scarring or uncertain cases.
Laboratory Investigations
Standard Screen (for diffuse loss in women):
- Ferritin: Iron deficiency is a common cause (Target >40-70 ng/mL for growth).
- TSH: Hypo/Hyperthyroidism cause hair loss.
- Vitamin D / B12: Optimizing supports growth.
- Hormonal Profile (FSH/LH/Testosterone/DHEAS): Only if signs of hyperandrogenism (PCOS symptoms).
Scalp Biopsy
- Indication: Suspected scarring alopecia (LPP, DLE, FFA) to confirm diagnosis and prevent permanent loss.
- Technique: 4mm punch biopsy. Often 2 samples (horizontal and vertical sectioning).
5. Management Algorithm
┌─────────────────────────────────────────────────────────────────────────────┐
│ ALOPECIA MANAGEMENT ALGORITHM │
├─────────────────────────────────────────────────────────────────────────────┤
│ │
│ DETERMINE TYPE (Scarring vs Non-Scarring) │
│ ↓ │
│ ┌──────────────────────────────────────┐ │
│ │ IS IT SCARRING? (Redness, │ │
│ │ Pain, Loss of pores) │ │
│ └──────────────────────────────────────┘ │
│ ↓ YES (Scarring) ↓ NO (Non-Scarring) │
│ ┌──────────────────────────┐ ┌──────────────────────────────────────┐ │
│ │ URGENT DERM REFERRAL │ │ DIAGNOSE SUBTYPE │ │
│ │ Goal: Halt progression │ │ 1. Androgenetic (Pattern) │ │
│ │ │ │ 2. Areata (Patchy) │ │
│ │ • Potent Topical Steroids│ │ 3. Telogen Effluvium (Diffuse) │ │
│ │ • Intralesional Steroid │ └──────────────────────────────────────┘ │
│ │ • Oral: Doxycycline, │ ↓ │
│ │ Hydroxychloroquine │ │
│ └──────────────────────────┘ │
│ │
│ ┌─────────────────────────┼──────────────────────────┐ │
│ ↓ ↓ ↓ │
│ ┌────────────────────┐ ┌───────────────────────┐ ┌───────────────────┐ │
│ │ ANDROGENETIC (Men) │ │ ANDROGENETIC (Women) │ │ ALOPECIA AREATA │ │
│ │ • Minoxidil 5% Top │ │ • Minoxidil 5% Foam │ │ • Intralesional │ │
│ │ • Finasteride 1mg │ │ • Spironolactone │ │ Steroids (<50%) │ │
│ │ Oral │ │ (Anti-androgen) │ │ • Potent Topical │ │
│ │ • Hair Transplant │ │ • Oral Minoxidil │ │ Steroids │ │
│ │ │ │ (Low dose) │ │ • JAK Inhibitors │ │
│ └────────────────────┘ └───────────────────────┘ │ (Severe/Totalis)│ │
│ └───────────────────┘ │
│ │
└─────────────────────────────────────────────────────────────────────────────┘
Management: Androgenetic Alopecia (AGA)
Men:
- Topical Minoxidil (5%): Prolongs anagen. Apply BD. Lifelong use.
- Oral Finasteride (1mg): 5α-reductase inhibitor. Stops conversion of T to DHT.
- Efficacy: Stops loss in 90%, regrowth in 60%.
- Side Effects: Sexual dysfunction (1-2%), reversible.
- Hair Transplant: FUE (Follicular Unit Extraction) relocates DHT-resistant hairs from back of head to front.
Women:
- Topical Minoxidil (5% Foam): Once daily.
- Anti-androgens (Off-label): Spironolactone or Cyproterone Acetate.
- Oral Minoxidil (Low dose): 0.25mg-1.25mg daily. Highly effective, avoids messy topicals. Causes hypertrichosis.
Management: Alopecia Areata (AA)
Limited Disease (<50% Scalp):
- Intralesional Corticosteroids (Triamcinolone): First line. Injected every 4-6 weeks.
- Potent Topical Steroids: Adjunctive.
Does not respond / Extensive (>50%):
- JAK Inhibitors (Baricitinib, Ritlecitinib): Breakthrough therapy. Restores hair in severe cases.
- Topical Immunotherapy (DPCP): Induces allergic contact dermatitis to distract immune system.
- Systemic Steroids: Bridge therapy only.
Management: Telogen Effluvium
- Self-limiting: Resolves in 6-12 months once trigger removed.
- Reassurance: "You are shedding, not going bald."
- Treat correctable causes: Iron, thyroid, diet.
6. Scarring Alopecias (Brief Overview)
Lichen Planopilaris (LPP):
- Perifollicular redness and scaling.
- Treatment: Potent steroids, Hydroxychloroquine.
Frontal Fibrosing Alopecia (FFA):
- "Clown alopecia" - recession of frontal hairline + eyebrow loss.
- Post-menopausal women.
- Treatment: 5α-reductase inhibitors + anti-inflammatories.
7. Prognosis
| Condition | Prognosis |
|---|---|
| Telogen Effluvium | Excellent. Complete regrowth expected. |
| Androgenetic | Progressive without treatment. Treatment maintains, rarely restores full density. |
| Alopecia Areata | 80% spontaneous regrowth in 1 year for mild cases. Poor prognosis if: onset in childhood, ophiasis pattern, or totalis/universalis. |
| Scarring | Irreversible loss. Goal is to stop progression. preservation. |
8. Complications
- Psychological Distress: Anxiety, depression, body dysmorphia.
- Sunburn: Scalp burn risk increased.
- Social Stigma: Particularly for women and children.
9. Special Considerations
Hair Loss in Children
- Tinea Capitis: Always rule out fungal infection. Scale + lymphadenopathy. Treat with ORAL antifungals (topicals fail).
- Alopecia Areata: Common in children. High association with atopy.
- Trichotillomania: Compulsive pulling. Look for odd shapes and different lengths.
Pregnancy
- Telogen Gravidarum: physiologic thickening during pregnancy (prolonged anagen), followed by massive shedding 3 months post-partum (Telogen Effluvium).
- Management: Reassurance. Resolves spontaneously.
10. Key Clinical Pearls
Exam-Focused Points
- Exclamation Mark Hairs: Pathognomonic for Alopecia Areata (taper towards scalp).
- Scarring vs Non-Scarring: The most important distinction. Look for loss of follicular ostia (smooth shiny scalp = scarring).
- Pull Test: Positive (>10% loose) means ACTIVE shedding (TE or active AA/LPP). Negative means stable or AGA.
- Ferritin: Target >40-70 ng/mL for optimal hair growth. Normal lab range (e.g., >15) is often too low for hair.
- Finasteride: Teratogenic. Women of childbearing potential must not handle crushed tablets or use it (unless on strict contraception).
- Tinea Capitis: Must treat with ORAL Griseofulvin/Terbinafine. Creams do not penetrate the hair shaft.
Common Exam Scenarios
- 30yo woman, diffuse shedding 3 months after having a baby. (Telogen Effluvium).
- Young man with coins-sized smooth bald patches. (Alopecia Areata).
- 60yo woman with receding hairline and eyebrow loss. (Frontal Fibrosing Alopecia).
11. Patient Explanation
Why Is My Hair Falling Out?
"Hair loss happens for different reasons.
- Genetic (Pattern) Balding: Your hair follicles are sensitive to hormones and shrink over time.
- Autoimmune (Alopecia Areata): Your immune system mistakenly attacks the hair root, making it fall out. The root is still alive, so hair can grow back.
- Shedding (Telogen Effluvium): Stress, illness, or hormonal shifts 'reset' the clock on your hairs, causing many to fall out at once. This usually happens 3 months after the trigger event."
Will It Grow Back?
"It depends on the type:
- Shedding (Stress/Post-partum): Yes, it almost always grows back on its own.
- Alopecia Areata: Yes, often on its own or with steroid injections.
- Pattern Balding: It won't grow back on its own, but we can stop it from getting worse and sometimes regrow hair with medication."
Do Shampoos Work?
"Most over-the-counter 'hair growth' shampoos do not work. The FDA-approved treatments are Minoxidil and (for men) Finasteride. Ketoconazole shampoo can help slightly by reducing inflammation."
12. Evidence & Guidelines
Key Guidelines
| Guideline | Organization | Year | Key Points |
|---|---|---|---|
| Alopecia Areata | British Association of Dermatologists | 2012 | Steroids first line, Immunotherapy for severe |
| Androgenetic Alopecia | European Dermatology Forum | 2017 | Finasteride/Minoxidil evidence based |
| Scarring Alopecia | BAD | 2020 | Early biopsy and aggressive anti-inflammatory Rx |
Landmark Trials
BRAVE-AA1 and BRAVE-AA2 (2022):
- Phase 3 trials for Baricitinib (JAK inhibitor) in severe Alopecia Areata.
- Showed significant hair regrowth (>80% scalp coverage) compared to placebo.
- Led to first FDA approval for severe AA.
Finasteride Trials (1998):
- Long-term (5 year) data showing cessation of hair loss in 90% of men.
Evidence-Based Recommendations
| Recommendation | Evidence Level |
|---|---|
| Oral Finasteride for Male AGA | High |
| Topical Minoxidil for AGA | High |
| Intralesional Steroids for Patchy AA | Moderate |
| JAK Inhibitors for Severe AA | High |
| PRP (Platelet Rich Plasma) | Low/Controversial |
13. References
-
Messenger AG, et al. British Association of Dermatologists' guidelines for the management of alopecia areata 2012. Br J Dermatol. 2012;166(5):916-926.
-
King B, et al. Two Phase 3 Trials of Baricitinib for Alopecia Areata. N Engl J Med. 2022;386(18):1687-1699.
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Kanti V, et al. Evidence-based (S3) guideline for the treatment of androgenetic alopecia in women and in men - short version. J Eur Acad Dermatol Venereol. 2018;32(1):11-22.
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Harries MJ, et al. Lichen planopilaris and frontal fibrosing alopecia as model epithelial stem cell diseases. Trends Mol Med. 2018;24(5):435-448.
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Adil A, Godwin M. The effectiveness of treatments for androgenetic alopecia: A systematic review and meta-analysis. J Am Acad Dermatol. 2017;77(1):136-141.e5.