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Alopecia   -  Outlines in Clinical Medicine on Physicians' Online 2002

A. Definitions

Alopecia means hair loss

Androgenic alopecia - baldness caused by miniaturization of susceptible follicles

Alopecia areata - hair loss in patches believed to be autoimmune

Permanent alopecia - caused by destruction of hair follicles

Anagen Effluvium (see below)

Telogen Effluvium (see below)

B. Scarring (Cicatricial) Alopecia (major causes only)

Inflammatory Dermatoses

Cicatricial pemphigoid

Lupus erythematosus - discoid and systemic

Necrobiosis lipoidica diabeticorum



Likely that most forms of alopecia have an autoimmune component


Bacterial - pyogenic, syphlis, tuberculosis, leprosy

Viral - herpes (varicella) zoster

Fungal and Protozoal infections

Physical and Chemical Agents


Basal cell carcinoma


Nevi and Melanoma

Metastatic Disease

Squamous cell carcinoma

Congenital Abnormalities

Aplasia cutis

Congenital ichthyosis

Epidermolysis bullosa

Hair follicle hamartoma

Ichthyosiform erythroderma

Keratosis pilaris atrophicans

C. Nonscarring Alopecia

Androgenic Alopecia [7]

Male common baldness

Affects ~65% of men

In women, often associated with acne, facial hirsutism (chronic anovulatory syndrome)

Common mechanism is androgen excess

Primary pathologic process due to androgen excess is called miniaturization

Miniaturization leads to conversion of large (terminal) hairs to small (vellus) hairs

Over time, the miniaturized hair follicles produce small, finer hairs

The number of follicles per unit of area remains the same

Young persons with androgenic alopecia have higher levels of 5alpha-reductase, more androgen receptors, and lower levels of P450 aromatase in frontal region hair follicles

Reducing androgen levels (dihydrotestosterone, DHT) can improve hair growth [3]

Telogen Effluvium

Diverse causes with anagen arrest

Hair loss (usually >50%) occurs 2-4 months after initiating event

Psychologic and pathologic causes and medications are often implicated

Drugs: anticoagulants, oral-contraceptive withdrawal, ß-blockers, tricyclics, ACE inhibitors, amphetamines, anti-thyroid medicines, lithium, levodopa, nicotinic acid

Other: hypothyroidism, fever, infection, severe systemic disease

Far more common than Anagen Effluvium

Anagen Effluvium

Drugs - colchicine, allopurinol, cimetidine, haloperidol, Vitamin A

Radiation and Chemotherapy

Heavy metal poisoning

Traumatic Alopecia

Trichotillomania - Nonscarring, patchy hair loss secondary to pulling out hair

Traction alopecia - tightly wound, braided hair

Alopecia Areata [7] See outline Lymphocytes

Autoimmune disease affecting ~2% of population in USA

Affects men and women equally

One or more asymptomatic circular to oval patches, usually sudden onset

May occur in small patches that regrow spontaneously, or persistent large patches

Atopy, vitiligo, and autoimmuen thyroid disease are more common in affected persons

Nail pitting is often present

Activated CD4+ and CD8+ T lymphocytes with reactivity to hair follicles are found

HLA-D (Class II MHC) associations have been observed

High levels of Tumor Necrosis Factor alpha (TNFa) have been found in lesions

Secondary syphilis

Congenital disorders

Many of these can eventually cause scarring

D. Treatments [7]

Finasteride [4] See outline Prostatic Hyperplasia

Reduction of DHT levels has been somewhat effective for androgenic alopecia [3]

Inhibitor of type 2 5-alpha-reductase (converts testosterone to DHT)

Finasteride (Propecia®), a 5-alpha reductase inhibitor, is FDA approved for hair growth

Finasteride, 1mg/day, reduces DHT levels ~65%, increases hair counts ~12%

Consider finasteride in women with polycystic ovary syndrome as well

Finasteride is contraindicated in women who may become or are pregnant

Minoxidil (Rogaine®) [5]

Induces and prolongs anagen stage, converts vellus to terminal follicles

Minoxidil is also an arteriolar vasodilator, can also improve hair counts slightly

5% and 2% solutions of minoxidil are FDA approved for promoting hair growth

Treatment requires 48 weeks or more for androgenic alopecia

Minoxidil (1 mL) is applied twice daily for effects

Side effects are irritation of the scalp including dryness

Hypertrichosis can occur in women using minoxidil

No effects on blood pressure are seen

Psoralen plus ultraviolat A (PUVA) has shown some efficacy [4]

Alopecia Areata

Glucocorticoids - topical or systemic See outline Glucocorticoids

Topical immunotherapy - induce contact sensitization

Anthrallin See outline Psoriasis

Minoxidil (see above)

Alopecia Totalis and Universalis

Relatively resistant to topical agents

PUVA has shown some activity but maintenance PUVA therapy required [4]


Nielsen TA and Reichel M. 1995. Am Fam Phys. 51(6):1513

Paus R and Cotsarelis G. 1999. NEJM. 341(7):491

Finasteride. 1998. Med Let. 40(1021):25

Weise K, Kretzschmar L, John SM, Hamma H. 1996. Dermatology. 192:129

Minoxidil. 1998. Med Let. 40(1021):26

Lebwohl M. 1997. Lancet. 349:222

Price VH. 1999. NEJM. 341(13):964