What is the definition or description of: ferritin?

Stored Iron: Ferritin is an itracellular stored iron and releases it in a controlled fashion!

Iron storage marker: Ferritin is protein complex that binds iron and controls iron levels inside all of our cells. Low levels in the serum is a useful marker of iron deficiency. Macrophages are cells that contain large amounts of ferritin, and this that helps them scavenge RBC at sites of old hemorrhage. High serum ferritin levels occurs from macrophage activation and is a non-specific marker of inflammation.