EVIDENCE-BASED ANSWER
It’s unclear what the best approach is given the lack of studies on this issue. Indirect evidence and expert opinion indicate that a careful history and thorough physical examination usually suggest the underlying cause of alopecia. Ancillary laboratory evaluation and scalp biopsy are sometimes necessary to make or confirm the diagnosis (strength of recommendation: C, expert opinion).
Clinical commentary
Scarring or nonscarring, that’s the question
Robert Gauer, MD
University of North Carolina Faculty Development, Fellowship 2006-2007, Fort Bragg
In my experience, evaluation of hair loss in women almost always fails to turn up a cause, and the alopecia typically resolves spontaneously within 6 to 12 months. I agree that the most useful investigations for ruling out specific etiologies are the history and physical examination.
The most important characteristic to evaluate is whether it is scarring or nonscarring. Scarring alopecia generally necessitates a biopsy. Identifying diffuse vs focal alopecia can further narrow the differential diagnosis.
The typical patient has diffuse, nonscarring hair loss in no defined pattern (central thinning suggestive of androgenic alopecia). Consider telogen effluvium as the likely diagnosis. It can result from chronic illness, postpartum state, recent surgery/anesthesia, rapid weight loss, diet (iron deficiency, vitamin A toxicity, and protein deficiency), thyroid disease, or medications. Many commonly prescribed drugs can cause hair loss, including anticoagulants, nonsteroidal anti-inflammatory drugs, β-blockers, H2 blockers, hormones, retinoids, and antihyperlipidemic agents.
Educating the patient, checking directed laboratory values occasionally, or modifying certain medications is often all that’s needed to reassure women with alopecia. Persistent, progressive scarring or patchy alopecia requires further investigation and possible dermatologic consultation.
Evidence summary
Our comprehensive literature search found no systematic reviews, randomized trials, or prospective cohort studies that answer this question. The differential diagnosis of clinical hair loss is large (TABLE). We reviewed indirect evidence and expert opinion to answer this Clinical Inquiry.
Clues in the history
A detailed history—including medication use, systemic illness, endocrine dysfunction, hair care practices, severe diet restriction, and family history—is key to establishing an accurate diagnosis of alopecia.1 Other significant considerations include the onset, duration, and pattern of hair loss; whether hair is broken or shed at the root; and whether shedding or thinning has increased.1,2 It’s also important to ascertain whether hair loss is limited to the scalp or affects other areas of the body.
A family history of alopecia areata or androgenic alopecia can point to a genetic cause. Acne or abnormal menses can indicate androgen excess, suggesting androgenic alopecia. Positive answers to thyroid screening questions can point to hypothyroidism, and abnormal diet patterns can suggest iron-deficiency anemia. Unusual hair care practices can cause traction alopecia.1
TABLE
Causes of nonscarring alopecia
| COMMON | LESS COMMON |
|---|---|
| Alopecia areata | Human immunodeficiency virus |
| Androgenetic alopecia | Hyperthyroidism |
| Drugs and other chemicals | Hypothyroidism |
| Telogen effluvium (both acute and chronic) | Iron deficiency |
| Tinea capitis | Nutritional deficiencies |
| Traction alopecia | Other systemic diseases |
| Secondary syphilis | |
| Systemic lupus erythematosus | |
| Trichotillomania | |
| Adapted from: Habif TP. Clinical Dermatology. A Color Guide to Diagnosis and Therapy. 4th ed. Edinburgh: Mosby; 2004:838-842. | |