Hair loss Flashcards
Key facts on hair numbers
Hair growth is asynchronous (i.e. continuous production and shedding)
Humans produce 1 km of hair a month
Approx. 50–100 hairs are shed daily without a reduction in density
The scalp contains, on average, 100 000 hair follicles
At least 25% of hair must be shed before a noticeable loss of density occurs
Hair loss counts consistently above 100/d indicate excessive hair loss
Significant hair loss tends to block the shower drain or be visible all over the pillow
Probability diagnosis
Androgenetic alopecia (male pattern baldness)
Alopecia areata (diffuse type)
Telogen effluvian (incl. postpartum)
Anagen effluvian (esp. cytotoxic therapy)
Seborrhoeic dermatitis
Causes of diffuse hair loss
Androgenetic alopecia
Telogen effluvium
Postpartum telogen effluvium
Alopecia areata (diffuse type)
Drugs—cytotoxics, anti-epileptics, various hormones, others
Hypothyroidism
Nutritional
- iron deficiency
- severe dieting
- zinc deficiency
- malnutrition
Post-febrile state
Anagen effluvium
Serious disorders not to be missed
Infection:
- tinea capitis
- bacterial folliculitis
- secondary syphilis
- post-febrile state
Cancer:
- treatment for cancer
Other:
- systemic disease (e.g. lupus)
Pitfalls (often missed)
Rarities:
- Heavy metal poisoning
Nutritional:
- severe dieting
- malnutrition
- zinc/iron deficiency
Masquerades checklist
Thyroid/other endocrine (hypothyroidism)
Drugs:
- cytotoxics
- anticoagulants
- anti-epileptics
- amphetamines
- anti-thyroid agents
- various hormones
- cessation OCP
Is the patient trying to tell me something?
Emotional stress → telogen effluvium. Trichotillomania.
Key history
Onset, duration, quantity and rate of loss
Localised or generalised loss
Characteristics of hair (e.g. scales, white bulbs)
Associated symptoms (e.g. pruritus, scaling, pustules)
Systems review; fever, acute illness, surgery, stressors
Endocrine features
Past history of skin disorders, cancer, thyroid disorders
FHx of hair loss
Drug history
Key examination
General review with emphasis on endocrine system and examination of scalp
Look for;
- exclamation mark hair
- ‘white bulb’ hair
- state of bald patch (clean, scaly, scarred or inflamed)
- unusual pattern of trichotillomania
Key investigations
FBE/ESR
pituitary hormones (FSH/LH/prolactin/TSH)
hair pull test
trichogram
scalp biopsy
skin scrapings and hair sample for fungal microsurgery and culture.
Androgenic alopecia
Diagnostic tips
Androgenetic (male pattern and female pattern hair loss) is the most common type.
Microscopic examination (light or electron) may be required for definitive diagnosis.
For patchy loss consider alopecia areata and trichotillomania.
Generalised loss: consider telogen effluvium, systemic disease and drugs.
In telogen effluvium, the traumatic event has preceded the hair loss by about 2 months (peak loss at 4 months). ‘White bulbs’ are diagnostic.
