Is it an iron deficiency?

This question was asked on the TTM mailer, and here is John Kender's answer

I couldn't find much about it, other than the American Dermatological Association notes that iron deficiency occasionally causes hair loss (presumably spontaneous). One other sourse also notes that it occasionally
causes picas, that is, the urge to eat non-food items. So maybe it does both: hair falls out, or kids go after it to eat it. Both conditions, however, appear rare, and from what I can tell, taking iron for TTM hasn't had any
result.