Low ferritin levels are a big cause of hair loss (ie. where our hemoglobin or "iron levels" stem from), and even though your hemoglobin levels might be OK, the ferritin levels could still be low. This is, as said, one of the many curses of chronic anemia in people with crohnic illnesses like IBD. So if your "iron levels" are low, chances are your ferritin levels are low, and even after you start taking an iron supplement, it may take a while to bring your ferritin levels back up to par.
The other thing that causes hair loss in chronically ill people is just when the body is under stress, so operations, huge changes in medications, or nasty flare ups. Some of this is related to stress (ie. kind of like the "fight or flight" response... ever notice how animals shed more when they are under stress? It's their natural way of escaping harm... hoping that their predator will only get a mouthful of hair, rather than skin and meat...lol).
Add to that the fact that our bodies don't absorb all the nutrients they need to produce things like hair and skin cells, and things start to fall off our bodies!! lol
