ALL photos in this note are from DermNet NZ – https://www.dermnetnz.org/topics/hair-loss/
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Remember these – 
      • Androgenic alopecia – the commonest ( 50% of men by 40 and females by 60 ) 
      • Alopecia areata – ( PATCHY LOSS with non inflamed normal skin  ) – bad prognosis if it begins in childhood and if there are several patches involved  
      • seborrheic dermatitis – see the yellow discharge 
      • Tenia capitis (Patchy losswith  inflamed  skin ) 
      • scalp psoriasis  – see the scales – silver colour 
      • Trichotalamenia ( Patchy loss with non inflamed normal skin ) 
      • Anagen Effluvium 
      • Telogen Effluvium
      • Lichen planus 
 
 
Algorithm
      • First look for patchy or full hair loss
      • if patchy – is the skin in the patch normal or inflamed 
      • If normal skin – its either Alopecia Areata or tricotalamenia
      • However, Alopecia Areata – complete hair loss in the patch
      • And Tricotalamenia – there is hair in the patch ( not complete loss of hair as the patient pulls him/her self ) 
      • If inflamed skin Tinea capitis, Seborrheic dermatitis or Psoriasis  are the D/D – ( however, silver scales are noted in psoriasis and scales are yellow in Seborrheic dermatitis ) 
      • if there is no patch, but generalised – after Chemo – its anagen effluvium 
      • if the number of hair lost in a day is around 100 -150 ( rather than usual 50 to 100/ more than usual hair loss ) – its telogen effluvium 
      • Lichen planus would have other signs in the body – so easy to differentiate from the above 
 
Alopecia Areata – Alopecia totalis – Alopecia Universalis – 
Alopecia Areata – patches of complete hair loss ( This is the only reason/diagnosis for complete patch of loss. In trichotalamenia visible small hair in the patch is noted
If the patch is small – it may recover – 
can trial topical steroids – or intra lessional steroids as a treatment 
if larger patches with > 50% loss – – referral to dermatologist for oral steroids 
 
Alopecia totalis- ( all hair in scalp lost ) – if in children – unlikely to recover – in healthy fit adults, may recover
Alopecia Universalis ( all hair in the body lost )  – would not recover 
 
 
Patchy hair loss – look at the skin in the patch – 
 
silver scales are noted in psoriasis and scales are yellow in Seborrhic dermatitis 
Tiena capitis – features of fungal infection can be notes in skin 
 
 
 
Traumatic forms of hair loss 
Note – Skin is usually normal 
 
 
Telogen Effuvium – 
Telogen hair has a bulb at the end (club hair). Excessive shedding is known as telogen effluvium
Scalp hair continues to grow but has a shorter natural length than normal.
Diffuse hair loss ( around 150 hair loss rather than the normal 50 – 100 ) 
It occurs 2–6 months after an event that stops active hair growth.
Telogen effluvium is caused by:
 
Hair would grow again 
recover in 5-6 months 
if not recovering after 6 months – refer to specialist. 
 
Anagen Effuvium
 

Anagen Effuvium is caused by 
      • Autoimmune disease – E.G – severe diffuse alopecia areata
      • Medications E.G – cytotoxic / chemotherapy drugs 
      • Inherited/congenital conditions E.G – loose anagen syndrome 
 
Short broken hairs and empty follicles may be observed. 
If caused by a drug or toxin, hair growth can return to normal within 3–6 months of its withdrawal.
 
 
Balding patters – Normal 
 
Pattern hair loss is due to genetic programming or hormonal influences. It is also called androgenetic alopecia because it is influenced by androgens.
Pattern alopecia is apparent in about 50% of individuals by the age of 50 years.
Male pattern alopecia affects vertex and temporal scalp.
Female pattern alopecia is less pronounced and affects the anterior scalp
 
 

Hair pull test –

Hair loss associated with excessive shedding results in a positive “gentle hair pull” test. Grasp a lock of hairs to determine if any can be extracted with firm pull. Normally 0-2 telogen hairs can be extracted: these are hairs in the resting phase, identified using magnification by a rounded bulb at the proximal end. An elongated or tapered end indicates anagen hair (growing phase); anagen hairs extracted by the gentle hair pull test are pathologic.

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