Ans. (b) FerritinRef. Robbings pathology 9th ed. /650* Ferritin is the storage and transferring the transport form of iron.* Hepcidin is released by liver in setting of anemia of chronic disease. Ferroportin is a transmembrane protein that transports iron from the inside of a cell to the outside of it. Ferroportin-1 plays an important role in neural tube closure and forebrain patterning.* REMEMBER: Ferroportein is inhibited by hepcidin, which binds to ferroportin and internalises it within the cell. This results in the retention of iron within cells, and a reduction in iron levels within the plasma. This is especially significant in enterocytes which are shed at the end of their lifespan where ferroportein is expressed on the basolateral membranes. The extra iron retained within them is not only prevented from entering the bloodstream but ends up being excreted into the faeces. Hepcidin is thus the "master regulator" of human iron metabolism.* In the setting of anemia, low serum ferritin is the most specific lab test for iron deficiency anemia. However it is less sensitive, since its levels are increased in the blood by infection or any type of chronic inflammation, and these conditions may convert what would otherwise be a low level of ferritin from lack of iron, into a value in the normal range. For this reason, low ferritin levels carry more information than those in the normal range. Low ferritin may also indicate hypothyroidism, vitamin C deficiency or celiac disease.