Iron and ferritin: the pathway in the body

This page shows the biochemical pathway behind the laboratory value Iron, iron (intracellular), ferritin: which stations follow one another, which enzymes carry out each step and which cofactors they use. Every statement has a source. The page describes general textbook knowledge and says nothing about any individual person.

In brief

Iron is a trace element that the body stores in the protein ferritin and distributes in the blood bound to transferrin. In the haem of haemoglobin it binds oxygen, and in many enzymes it transfers electrons.

The pathway step by step

1. Iron in food → Fe²⁺ in the gut Dcytb · Vitamin C The enzyme Dcytb sits on the surface of the gut cell. It donates an electron and turns Fe³⁺ into ferrous Fe²⁺; vitamin C supplies the electrons for this. Source 5, 1
2. Fe²⁺ in the gut → Iron in the gut cell DMT1 The transporter DMT1 moves Fe²⁺ into the cell. There it is either stored in ferritin or passed on into the blood. Source 1
3. Iron in the gut cell → Transferrin iron Ferroportin · Hephaestin (copper) Ferroportin is the only known door through which iron leaves a cell. Hephaestin oxidises it back to Fe³⁺ on the way; in the blood it binds to transferrin. Source 1, 2
4. Iron in the cell → Ferritin Ferroxidase (H chain) Ferritin is a hollow sphere made of 24 subunits. Its H chains oxidise Fe²⁺ and deposit it as a mineral inside – this keeps the iron safely stored. Source 3
5. Ferritin → Ferritin in blood A small part of the ferritin passes from cells into the blood. This form is largely iron-free and is the one measured in the laboratory. Source 3, 2
6. Iron in the cell → Haem Ferrochelatase · Protoporphyrin IX In the mitochondrion, ferrochelatase inserts Fe²⁺ into the protoporphyrin IX ring. This forms haem, the red pigment that binds oxygen. Source 4
7. Haem → Haemoglobin · Globin chains Four haem groups and four globin chains form haemoglobin. Most of the body's iron is found in this molecule. Source 4, 1

Cofactors in this pathway

• Vitamin C — Supplies Dcytb with the electrons that turn Fe³⁺ into Fe²⁺ in the gut Source 5In the ORY catalogue as a laboratory value: Vitamin C (Ascorbinsäure)
• Copper — Metal of the ferroxidase hephaestin, which oxidises iron to Fe³⁺ as it enters the blood Source 1, 2In the ORY catalogue as a laboratory value: Kupfer (Cu)
• Vitamin B6 — Cofactor of ALA synthase, the first enzyme of haem synthesis Source 4In the ORY catalogue as a laboratory value: Vitamin B6
• Glycine — Building block from which ALA synthase forms the haem precursor ALA with succinyl-CoA Source 4In the ORY catalogue as a laboratory value: Glycin
• Zinc — Metal of ALA dehydratase, the second enzyme of haem synthesis Source 4In the ORY catalogue as a laboratory value: Zink

What acts on this pathway

• Hepcidin — Hepcidin is a hormone made by the liver. It binds to ferroportin and causes it to be broken down; the gut cell then releases less iron into the blood. Higher hepcidin levels in the blood have been described during inflammation. Source 2

Sources

1. Anderson GJ, Frazer DM. Current understanding of iron homeostasis. Am J Clin Nutr 2017 · PubMed 29070551
2. Ganz T. Systemic iron homeostasis. Physiol Rev 2013 · PubMed 24137020
3. Plays M, Müller S, Rodriguez R. Chemistry and biology of ferritin. Metallomics 2021 · PubMed 33881539
4. Ajioka RS, Phillips JD, Kushner JP. Biosynthesis of heme in mammals. Biochim Biophys Acta 2006 · PubMed 16839620
5. McKie AT. The role of Dcytb in iron metabolism: an update. Biochem Soc Trans 2008 · PubMed 19021532
6. Gao G, Li J, Zhang Y et al. Cellular Iron Metabolism and Regulation. Adv Exp Med Biol 2019 · PubMed 31456203

Related pathways

• HbA1c and insulin — haemoglobin
• 8-OHdG — Vitamin C (Ascorbinsäure), Kupfer (Cu)
• Dopamine, noradrenaline, adrenaline — Vitamin C (Ascorbinsäure), Kupfer (Cu)
• Carnitine — Vitamin C (Ascorbinsäure), Vitamin B6
• Folic acid — Vitamin B6, Zink

As of 2026-09-16. Draft written by Claude to schema v2; sources checked in PubMed; expert review pending
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