Makindo Medical Notes

🔎 Ferritin is an acute phase reactant — it often rises with inflammation or infection, mirroring CRP. Therefore, ferritin does not always reflect true iron stores and should be interpreted in the clinical context.

📖 Overview of Ferritin

• 🧪 Ferritin is a protein complex that stores iron in a safe, soluble form and releases it in a controlled way.
• ⚖️ Essential for iron homeostasis. Found in liver, spleen, bone marrow, and skeletal muscle.
• 🩸 Blood ferritin levels generally reflect body iron stores, but may be confounded by inflammation.

🧬 Structure of Ferritin

• Composition:
  • 24 protein subunits form a hollow spherical shell.
  • Two types of chains: Heavy (H) and Light (L), encoded by separate genes.
  • Different tissue types contain different H:L ratios depending on metabolic needs.
• Iron Storage:
  • Each ferritin molecule can hold up to ~4,500 iron atoms as ferric hydroxide–phosphate complexes.
  • Prevents free iron toxicity (⚡ free radicals via the Fenton reaction).

⚙️ Functions of Ferritin

• Iron Storage & Release:
  • Acts as an iron buffer — storing excess and releasing when needed (e.g., for RBC production, DNA synthesis, mitochondrial respiration).
  • Iron release is tightly regulated to avoid toxicity.
• Protection Against Oxidative Stress:
  • By binding iron, ferritin reduces oxidative stress and tissue damage from free radicals.

🎛 Regulation of Ferritin Levels

• Iron Levels: ↑ ferritin synthesis with high intracellular iron.
• Inflammation: 📈 Rises as an acute phase reactant in infection, malignancy, autoimmune disease.
• Hormonal Regulation: Hepcidin from the liver modulates iron absorption and ferritin storage.

🏥 Clinical Significance

• Iron Deficiency 🔻
  • Low ferritin = depleted iron stores (sensitive marker unless inflammation is present).
  • Symptoms: fatigue, pallor, exertional dyspnoea, brittle nails.
• Iron Overload 🔺
  • High ferritin suggests haemochromatosis or transfusional iron overload.
  • May lead to liver cirrhosis, diabetes, cardiomyopathy, skin pigmentation.
  • Management: phlebotomy or chelation therapy.
• Inflammation & Chronic Disease 🩺
  • Ferritin rises with chronic infections, autoimmune conditions, cancers.
  • In such cases, ferritin reflects inflammation more than iron reserves.
• Ferritin Testing 🔬
  • Used in anaemia work-up: low ferritin = iron deficiency (unless confounded).
  • Must be interpreted alongside CRP, transferrin saturation, and full blood count.

📊 Clinical Pearls

• Ferritin <30 μg/L → highly suggestive of iron deficiency (unless inflammation).
• Ferritin >300 μg/L (men) or >200 μg/L (women) → consider iron overload, liver disease, inflammation.
• Always interpret ferritin with CRP/ESR and clinical context.

✅ Summary

Ferritin is the body’s iron bank 🏦 — storing, protecting, and releasing iron as needed. Low ferritin points to iron deficiency, high ferritin suggests iron overload or inflammation. Because it is also an acute phase protein, careful interpretation alongside other labs is essential.