• Tinea capitis – “ringworm”, actually fungal.  Scalp abnormal.
• Telogen effluvium – lots of hair shed all at the same time following some sort of trigger esp birth (both baby and mother can be affected!), infection.  Trigger usually 2-3 months preceding.  Clumps or general thinning.
• Alopecia areata
• Trichotillomania

On Examination

Exclamation mark hairs (thin proximally, at scalp, normal distally) suggest alopecia areata, but may be seen in trichotillomania, so not very predictive.

Pull test – gentle traction on about 20 hairs in 3 different locations.  Positive if more than 5 hairs extracted – suggests active alopecia areata.  You may miss dormant alopecia areata, but in that case hair regrowth should occur anyway.