How is iron stored in the body?

The body stores iron primarily in the form of ferritin and hemosiderin.

Iron is essential for various bodily functions, most notably oxygen transport via hemoglobin. However, free iron can be toxic. Therefore, the body employs sophisticated mechanisms to store and transport iron safely.

Ferritin: The Primary Iron Storage Protein

Ferritin is the major iron storage protein in the body. It's a spherical protein shell that can store thousands of iron atoms in its core as ferric iron (Fe³⁺).

• Location: Ferritin is found in nearly all tissues, but is most abundant in the liver, spleen, bone marrow, and skeletal muscle.
• Function: It acts as a readily available reservoir of iron, releasing iron when needed for processes like red blood cell production.
• Regulation: Ferritin levels are directly proportional to the amount of iron stored in the body. Measuring serum ferritin levels is a common diagnostic test to assess iron stores.

Hemosiderin: Long-Term Iron Storage

Hemosiderin is another form of iron storage, representing partially digested ferritin. It's considered a long-term storage form and accumulates when there's an excess of iron.

• Location: Primarily found in the liver, spleen, and bone marrow.
• Formation: It forms when ferritin is degraded, and iron is released. The released iron aggregates with other cellular components.
• Availability: Iron stored as hemosiderin is less readily available than iron stored as ferritin.
• Clinical Significance: Excessive hemosiderin deposition can occur in conditions like hemochromatosis (iron overload), leading to organ damage.

Iron Storage in Different Organs

• Liver: The liver is a primary site for both ferritin and hemosiderin storage, playing a crucial role in iron homeostasis.
• Spleen: The spleen stores iron recovered from old or damaged red blood cells.
• Bone Marrow: Iron stored in the bone marrow is essential for the production of new red blood cells.
• Other tissues: Smaller amounts of ferritin are present in most other tissues, including the duodenum (where iron absorption occurs) and skeletal muscle.

In summary, the body carefully regulates iron storage using ferritin and hemosiderin. Ferritin provides a readily available iron reserve, while hemosiderin is a long-term storage form that becomes more prominent when iron levels are high. These storage mechanisms prevent the harmful effects of free iron and ensure that iron is available when and where it's needed.