Hair Loss, Balding, Hair Shedding. Dermnet Nz
Hair loss, balding, hair shedding. DermNet NZ
12/24/2007 07:12 PM
DermNet NZ
Authoritative facts about the skin from the New Zealand Dermatological Society Incorporated.
Home | Hair, scalp, nails & sweating
Hair loss
Dermatologists comment that scalp hair loss seems to provoke more distress than many severe skin conditions.
Unfortunately, hair loss may not be easy to remedy.
What causes hair loss?
Hair loss can be due to:
Decreased growth of the hair
Increased shedding of the hair
Breakage of hairs
Conversion of thick terminal hairs to thin vellus hairs
Hair cycle
Hair grows in a cycle: anagen (living growing hair), catagen (in-between phase) and telogen (resting or falling-out
phase). Recently a new phase, ketogen, has been recognised; this is when the follicle is empty, after the telogen
hair has fallen out and before the anagen hair is visible on the scalp.
Image © 1998 Merck Sharpe & Dohme (with permission)
Anagen hair loss
Anagen normally lasts two to seven years. Hair loss occurs when anagen is interrupted by certain medications
(e.g. anti-cancer drugs), or by the ‘autoimmune’ disease, alopecia areata. Anagen hair is tapered or broken-off.
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Hair loss, balding, hair shedding. DermNet NZ
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Anagen hair loss
Hair shedding during chemotherapy
Hair lost through chemotherapy
Alopecia areata
Telogen hair loss
Telogen lasts a few months and is terminated by a new anagen hair. The result is shedding a hair with a bulb at
the end (club hair). It is normal to lose 50 or more telogen hairs a day, rather more in autumn and winter.
Excessive shedding results in telogen effluvium, often a couple of months after an event such as child-bearing,
fever, an operation, weight loss or certain medications. Sometimes there appears to be no recognisable cause,
and the shortened hair cycle can continue for years (chronic telogen effluvium).
New growth can be seen at the hairline as a sign of recovery.
Telogen effluvium
Pattern hair loss (androgenetic alopecia)
Genetic and hormonal influences result in gradual thinning of scalp hair with age as male or female pattern
(androgenetic) hair loss. In some families this type results in male pattern alopecia and in others, considerable
thinning in females (female pattern alopecia).
Pattern balding
Male pattern balding
Female pattern balding
Severe female pattern hair loss
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Male pattern balding
Female pattern balding
Severe female pattern hair loss
Internal conditions
Other causes of hair loss are associated with poor quality hair:
Iron deficiency
Deficiency of thyroid hormone
Replacement of iron or thyroid hormone respectively may result in prompt regrowth.
Hair shaft abnormality
If hair loss first occurs in childhood, it may be due to a genetic hair shaft abnormality. These are diagnosed by
microscopic examination of the hair, and sometimes by scanning electron microscopy. A large number of
different types of hair shaft abnormaility have been described, including:
Fractures: trichorrhexis nodosa, trichoschisis, trichoclasis (trichothiodystrophy)
Irregularities: trichorrhexis invaginata (seen with ichthyosis in Netherton's syndrome), Marie-Unna
hypotrichosis (uncombable hair), pili bifurcati, pili annulati, pseudopili annulati, monilethrix (beaded hair),
pseudomonilethrix
Coiling and twisting: pili torti (twisted hair), wooly hair, trichonodosis (knotted hair)
Anagen hair loss in a child may be due to ‘loose anagen syndrome’. Clumps of hair come out with combing. The
hair loss gradually becomes less as the child becomes an adult.
Scarring alopecia
Trauma, infection and various skin diseases may injure the hair follicle resulting in localised areas of scarring and
bald patches in which there are no visible follicles; this is called ‘cicatricial alopecia’.
Infections that may cause cicatricial alopecia include Staphylococcal folliculitis or boils, and animal ringworm
infection (tinea capitis).
Skin diseases that may cause cicatricial alopecia include folliculitis decalvans, lichen planopilaris, frontal fibrosing
alopecia, alopecia mucinosa, discoid lupus erythematosus and scleroderma. Scarring hair loss of unknown cause
is known as pseudopelade.
Scarring alopecia
Discoid lupus erythematosus
Folliculitis decalvans
Lichen planopilaris
Scalp conditions
Although they may cause permanent balding if neglected, early treatment of scalp infections such as tinea capitis
prevents permanent baldness.
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Hair loss caused by psoriasis, in which there are thick plaques of scale, recovers once the skin condition is
controlled. Seborrhoeic dermatitis or atopic dermatitis can sometimes also cause hair loss temporarily.
Hair loss due to scalp conditions
Tinea capitis
Psoriasis © R Suhonen
Seborrhoeic dermatitis
Trauma
Hair can be pulled out by tight curlers or certain hair styles, sometimes resulting in permanently thinned areas
(traction alopecia). The hair shafts can be broken by heat (hair dryer), or chemicals (perming solution or bleach)
or brushing too often.
Trichotillomania is a form of alopecia resulting from repetitive pulling, plucking and breaking of one's own hair.
Traumatic forms of alopecia
Trichotillomania
Trichotillomania
Traction alopecia
Image supplied by Dr John Adams
Related information
On Dermnet:
Alopecia areata
Male pattern hair loss
Female pattern hair loss
Telogen effluvium
Alopecia mucinosa
Hair replacement
Other web sites:
Practical Management of Hair Loss from UBC (for health professionals)
Cicatricial Alopecia Research Foundation
Emedicine dermatology, the online textbook
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Traction alopecia
Alopecia areata
Androgenetic alopecia
Alopecia Mucinosa
Tufted Hair Folliculitis
Menkes Kinky Hair Disease
Trichorrhexis Invaginata (Netherton Syndrome or Bamboo Hair)
Hair loss webcasts from Healthology
Books:
See the DermNet NZ bookstore
DermNet does not provide an on-line consultation service.
If you have any concerns with your skin or its treatment, see a dermatologist for advice.
Created 1998. Last updated 08 Sep 2007. © 2007 NZDS. Disclaimer.
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