Ferritin and Iron Deficiency Quiz

Ferritin and Haemosiderin

• Ferritin is the main iron storage protein found in bone marrow, liver, and spleen.
• It's made of apoferritin and iron-phosphate-hydroxide (ferrihydrite)
• Apoferritin has catalytic activity, oxidizing Fe²⁺ to Fe³⁺.
• Ferritin is a water-soluble, hollow sphere with 24 subunits.
• Up to 4500 iron atoms can be stored in a single ferritin molecule.
• 1 µg/L of serum ferritin corresponds to about 8 mg of stored iron.
• Iron is incorporated into the ferritin core as Fe³⁺ through pores in the protein.

Iron Deficiency Diagnosis

• A low ferritin level is strong evidence of iron deficiency.
• Ferritin is an indicator of accessible iron stores.
• Borderline ferritin levels should be assessed alongside C-reactive protein (CRP).
• Iron deficiency is suggested by ferritin levels <12 µg/L in children under 5 and <15 µg/L in those over 5 years old.
• Ferritin levels increase in inflammatory states (e.g., kidney disease, liver disease, malignancy), making it an acute-phase reactant.
• UK guidelines suggest investigating iron deficiency with levels below 150 µg/L.

Haemosiderin

• Haemosiderin is an insoluble iron-protein aggregate.
• Haemosiderin acts as long-term iron storage, unlike ferritin.
• It's not easily mobilized.
• When stained with Prussian blue, haemosiderin appears blue.
• Haemosiderin is examined in bone marrow, liver biopsies, or urine samples when intravascular haemolysis is suspected.
• It's useful for evaluating iron overload and identifying ring sideroblasts.
• Ferric iron + potassium ferrocyanide → ferric ferrocyanide (Prussian blue)

Microscopic Analysis (Perl's Stain)

• Perl's stain is used to visualize iron stores in tissues.
• Microscopic images stained with Perl's stain can show increased iron stores in iron overload conditions.

Recommended Tests for Iron Deficiency

• Full blood count with red blood cell parameters, serum ferritin, C-reactive protein (CRP) are the initial tests to check for iron deficiency.
• If acute/chronic inflammation is present or CRP is elevated, further tests may be needed.
• In cases with ferritin <15 µg/L, the suspicion of iron deficiency is high and further investigation is required.