🩸 Hematology & Oncology🟢 BasicIron Metabolism

Iron Metabolism and Absorption

How the body absorbs, transports, stores and recycles iron, a metal needed for haemoglobin but toxic in excess, so its level is tightly controlled.

Key points

Non-haem iron is absorbed mainly in the duodenum, where the ferrous (Fe2+) form is absorbed better than the ferric (Fe3+) form, so vitamin C, which keeps iron reduced, aids its absorption; haem iron is absorbed efficiently by a separate route.
Because the body has no active way to excrete iron, absorption itself is the main control point, governed by the liver hormone hepcidin.
Hepcidin blocks the export channel ferroportin, so when iron stores are high hepcidin rises and absorption falls, and when stores are low hepcidin falls and absorption rises.
In the blood iron travels bound to the transport protein transferrin, and it is stored inside cells bound to ferritin, with haemosiderin as an overflow store.
Most of the body's iron is recycled from old red cells broken down by macrophages, so only a little dietary iron is needed each day to replace losses.
Too little iron causes a microcytic hypochromic anaemia, while iron overload, as in haemochromatosis, deposits iron in the liver, pancreas and heart and damages them.

Hepcidin is the iron gatekeeper: high stores raise hepcidin and shut ferroportin, so absorption drops; low stores drop hepcidin and let iron in.

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🩸 Hematology & Oncology🟢 BasicIron Metabolism

How the body absorbs, transports, stores and recycles iron, a metal needed for haemoglobin but toxic in excess, so its level is tightly controlled.

Non-haem iron is absorbed mainly in the duodenum, where the ferrous (Fe2+) form is absorbed better than the ferric (Fe3+) form, so vitamin C, which keeps iron reduced, aids its absorption; haem iron is absorbed efficiently by a separate route.
Because the body has no active way to excrete iron, absorption itself is the main control point, governed by the liver hormone hepcidin.
Hepcidin blocks the export channel ferroportin, so when iron stores are high hepcidin rises and absorption falls, and when stores are low hepcidin falls and absorption rises.
In the blood iron travels bound to the transport protein transferrin, and it is stored inside cells bound to ferritin, with haemosiderin as an overflow store.
Most of the body's iron is recycled from old red cells broken down by macrophages, so only a little dietary iron is needed each day to replace losses.
Too little iron causes a microcytic hypochromic anaemia, while iron overload, as in haemochromatosis, deposits iron in the liver, pancreas and heart and damages them.

Hepcidin is the iron gatekeeper: high stores raise hepcidin and shut ferroportin, so absorption drops; low stores drop hepcidin and let iron in.