Hair loss

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Chapter 15 HAIR LOSS

Theodore O’Connell

Hair loss, or alopecia, can be classified in various ways, but the most common classification distinguishes nonscarring from scarring alopecia. The hair loss of scarring alopecia is permanent, whereas that of nonscarring alopecia usually is reversible. When a patient presents with hair loss, it is important to determine whether he or she is experiencing hair shedding, which is significant amounts of hair coming out, or hair thinning, in which more scalp is visible without noticeable amounts of hair falling out.

Every hair follicle goes through three phases: anagen (growth), catagen (transition between growth and resting), and telogen (resting). At any given time, approximately 85% of scalp follicles are in the anagen phase, and follicles remain in this phase for an average of 3 years. The catagen phase affects 2% to 3% of hair follicles at a time. The telogen phase occurs last, during which 10% to 15% of hair follicles undergo a rest period of about 3 months. At the end of telogen, the dead hair is ejected from the skin, and the cycle is repeated.

Alopecia areata is patchy hair loss of autoimmune origin. It usually occurs in well-circumscribed patches, but it also may involve the entire scalp (alopecia totalis) or body (alopecia universalis). The involved scalp may be normal, or subtle erythema or edema may be present. Short hairs that taper closer to the scalp surface, known as exclamation-mark hairs, are characteristic of alopecia areata. Alopecia areata may be associated with thyroid disease, vitiligo, or atopy. If a patient does not have any of these medical conditions and is otherwise healthy, no laboratory tests are necessary.

Androgenic alopecia, the most common form of alopecia in men and women, is also known as male-pattern balding, female-pattern balding, and common balding. Most patients with androgenic alopecia complain of thinning hair rather than shedding of hair. In some women, androgenetic alopecia may be a manifestation of hyperandrogenism; therefore, the history should focus on related signs such as menstrual irregularities, infertility, hirsutism, and acne. In an otherwise healthy woman with slowly progressive androgenetic alopecia and no signs or symptoms of hyperandrogenism, no laboratory testing is required.

Cicatricial alopecia results from a condition that damages the scalp and hair follicle. Examination typically reveals plaques of erythema with or without scaling. Syphilis, tuberculosis, acquired immunodeficiency syndrome (AIDS), herpes zoster, discoid lupus erythematosus, sarcoidosis, radiation therapy, and scalp trauma such as burns have been linked to cicatricial alopecia. If the cause of the disorder is not apparent, a punch biopsy of the scalp may be helpful in making the diagnosis.

Scarring alopecia represents a heterogeneous group of diseases manifested by erythematous papules, pustules, or scaling around hair follicles, resulting in eventual obliteration of follicular orifices.

Senescent (senile) alopecia is the steady decrease in the density of scalp hair that occurs in all persons as they age. Patients note a slow, steady, diffuse pattern of thinning hair beginning about age 50 years.

Syphilitic alopecia should be considered in every patient with unexplained hair loss. Hair loss may be rapid or slow and insidious and may be patchy (moth-eaten in appearance) or diffuse. Syphilitic alopecia is noninflammatory, nonscarring alopecia without erythema, scaling, or induration. However, in symptomatic syphilitic alopecia, the patchy or diffuse alopecia is associated with the papulosquamous lesions of secondary syphilis on the scalp or elsewhere.

Telogen effluvium occurs when an abnormally high percentage of normal hairs from all areas of the scalp enter telogen, the resting phase of hair growth. Many factors can precipitate telogen effluvium, especially stress. This disorder also may develop because of normal physiologic events such as the postpartum state or because of medications or endocrinopathies. Telogen effluvium usually begins 2 to 6 months after the causative event and lasts for several months. Hair loss is diffuse and may also affect pubic and axillary hair. Telogen effluvium is noninflammatory, and the scalp surface appears normal. The hair pull test yields positive results, although the telogen count usually does not exceed 50%.

Tinea capitis is a common condition caused by dermatophytes. Tinea capitis manifests with one or several patches of alopecia, as well as scalp inflammation. Broken-off hair shafts may create a black-dot appearance on the scalp. Fungal organisms can be displayed in a potassium hydroxide (KOH) preparation or may be cultured after adequate scraping of hair stubs from the periphery of the lesion.

Traction alopecia is a form of traumatic alopecia linked to certain methods of hair styling, including braiding, use of tight curlers, and ponytails. The outermost hairs are subjected to the most tension, and a zone of alopecia develops between braids and along the margin of the scalp.

Trichotillomania is a psychiatric impulse-control disorder in which the patient plucks the hairs. The pattern of hair loss is often suggestive of the diagnosis. One or more well-circumscribed areas of hair loss may be present, often in a bizarre pattern with incomplete areas of clearing. The scalp may be normal, or there may be areas of erythema or pustule formation. Laboratory testing is not required, but psychiatric consultation may be considered.

Medications Associated with Hair Loss

Anticonvulsants

Antithyroid agents

Chemotherapy agents

Causes of Hair Loss

Key Physical Findings

✓ Assessment of pattern of hair loss (patterned vs. diffuse hair loss)

✓ Examination of the scalp for erythema, scaling, pustules, edema, bogginess, sinus tract formation, or obliteration of follicular openings

✓ Examination of the hair shaft for caliber, shape, length, and fragility

✓ Thyroid examination

✓ Pubic or axillary hair loss

✓ Evidence of hirsutism

Suggested Work-Up

Hair pull test

Fifty to 60 hairs are grasped between the thumb and the index and middle fingers and then gently but firmly pulled. A negative test result is six or fewer hairs obtained. A positive result is more than six hairs obtained and indicates a process of active hair shedding. Microscopic evaluation of the hairs may be performed. The hair pull test is helpful in suspected cases of telogen effluvium, tinea capitis, systemic diseases, alopecia areata, alopecia totalis, alopecia universalis, and environmental factors.

Serologic test for syphilis

Recommended for all patients with unexplained hair loss to rule out syphilis

Additional Work-Up

KOH preparation for fungal elements or fungal culture of skin	In patchy forms of alopecia, to rule out fungal infection
Total testosterone, free testosterone, dehydroepiandrosterone sulfate, and prolactin level measurements	In women suspected of having hyperandrogenism
Thyroid-stimulating hormone (TSH) measurement, rapid plasma reagin (RPR) test, prolactin measurement, complete blood cell count (CBC), chemistry profile, measurement of erythrocyte sedimentation rate (ESR), antinuclear antibody (ANA) measurement, rheumatoid factor measurement, and hair pluck test for telogen:anagen ratio	In patients with telogen effluvium
CBC, ESR measurement, ANA measurement, rheumatoid factor measurement	In patients with alopecia areata
KOH examination or culture swab	In suspected cases of tinea capitis
Scalp biopsy	If the cause is unclear or if the patient fails to improve after appropriate treatment

FURTHER READING

Sperling LC, Mezebish DS. Hair diseases. Med Clin North Am. 1998;82:1155-1169.

Springer K, Brown M, Stulberg DL. Common hair loss disorders. Am Fam Physician. 2003;68:93-102.

Thiedke CC. Alopecia in women. Am Fam Physician. 2003;67:1007-1014.

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