diagnostic approach to alopecia (hair loss)

Last reviewed 08/2023

Alopecia can be either scarring or nonscarring. Androgenic alopecia (AGA), alopecia areata, and telogen effluvium are the most common causes of nonscarring alopecia.

Considerations in diagnosis of cause of hair loss:

  • What is the duration and pattern of hair loss (diffuse versus local)?
    • in diffuse hair loss, ask if the loss is predominantly hair thinning or shedding, if there is a relationship to any inciting event, and if there are symptoms of anemia, hyperandrogenism, or thyroid disease. The patient who presents with gradual hair thinning most likely has male or female pattern hair loss recognized by the typical patterns
    • patients with hair shedding may have telogen effluvium or diffuse alopecia areata, both of which cause a positive hair pull test
      • history may reveal the precipitating event in telogen effluvium, whereas patients with alopecia areata may have exclamation point hairs. In all patients with diffuse hair loss, serum ferritin and thyroid function tests should be ordered
      • syphilis is a rare cause of telogen effluvium, but should be ruled out if risk factors are present
  • Is hair coming out by the roots, or is it breaking?
    • hair coming out by the roots include
      • telogen effluvium
      • androgenic alopecia
      • alopecia areata
      • drug induced alopecia
    • broken hairs in alopecia suggest possible:
      • tinea capitis (1)
      • structural hair shaft abnormalities
      • breakage due to improper use of hair-care cosmetics
      • anagen arrest
  • Is it scarring or non-scarring alopecia?
    • patients with scarring should be referred to a dermatologist. In nonscarring focal alopecia, alopecia areata or tinea capitis are most common. In alopecia areata, the lesion is round and smooth, whereas in tinea capitis, the skin can look slightly scaly and erythematous, and there may be occipital adenopathy
  • Is increased shedding or increased thinning apparent?
  • What was age of onset?
  • Does patient take any drugs?
  • Is there a relationship with menses, pregnancy, or menopause?
    • coincidental acne and abnormal menstrual cycles can indicate an androgen excess causing AGA
  • What is present and past health?
  • Is thyroid gland functioning?
  • Is there generalised hair loss?
    • ask about loss of axillary and pubic hair, eyelashes, eyebrows, and body hair, because any hair-bearing area can be affected by alopecia areata or trichotillomania
  • Is there a family history of hair loss?
    • a family history of alopecia areata or AGA can point to a genetic predisposition for hair loss
  • Does patient have unusual hair care or use hair cosmetics?
    • some hair-care practices (eg, bleaching, back-combing, permanent waving) break hair.
  • What is patient's diet?
    • a strict vegetarian diet can implicate iron deficiency anemia

Clinical examination of alopecia:

  • examination should be performed in three stages
    • inspect the scalp for inflammation, scale, and erythema. It is important to determine whether hair loss is associated with scalp scarring
      • non-scarring alopecia - causes include:
        • Androgenic alopecia
        • Telogen effluvium
        • Alopecia areata
        • Traction alopecia
        • Tinea capitis
        • nonscarring alopecias demonstrate visible follicular units, while scarring alopecias are devoid of follicular units
      • scarring alopecia - causes include:
        • Discoid lupus erythematosus
        • Lichen planus
        • Severe fungal, viral, or bacterial infection (1)
        • Injury or burn
    • examine the pattern of distribution and density of hair
    • study the quality of the hair shaft in terms of calibre, fragility, length, and shape
      • to determine the ongoing activity of hair loss, a useful ancillary test, the 'pull test' should be conducted
        • approximately 60 hairs are grasped between the thumb, index finger, and middle fingers from the base near the scalp, and firmly, but not forcefully, tugged away from the scalp
        • if more than 10%, or six hairs, are pulled away from the scalp, this constitutes a positive pull test and implies active hair shedding. If fewer than six hairs can be easily pulled out, this is considered normal physiologic shedding. The patient must not shampoo for at least 1 day before the pull test
        • pull test helps to assess severity and location of hair loss

Laboratory investigations in alopecia:

  • ferritin
  • TFTs
  • in women with AGA and such virilizing signs as hirsutism, acne, or irregular menses, an endocrinologic workup consisting of free testosterone, androstenedione, and dehydroepiandrosterone (DHEA) is advised to rule out hyperandrogenism
  • if confirmed scarring alopecia due to discoid lupus erythematosus, an antinuclear antibodies (ANA) examination should performed

Reference:

Related pages:

alopecia

pull test (alopecia)