Iron Cycle Flashcards
Which form of iron is best absorbed in the intestine?
Heme iron & Ferrous iron (Fe²⁺)
What is the main site of iron absorption in the gastrointestinal tract?
Duodenum
Which protein transports iron from enterocytes into the bloodstream?
Ferroportin.
What is the role of DMT1 (Divalent Metal Transporter 1)?
Transports iron across the intestinal epithelium.
What enhances non-heme iron absorption?
Vitamin C
What enzyme reduces **Fe³⁺ (Ferric) to Fe²⁺ (Ferrous) in enterocytes for absorption?
Ferrireductase (Dcytb).
Which protein stores iron inside enterocytes?
Ferritin.
What happens to iron after being exported from enterocytes?
Hephaestin oxidizes Fe²⁺ to Fe³⁺ for transport by transferrin
Which protein binds iron in plasma and delivers it to cells?
Transferrin
What condition reduces intestinal iron absorption?
Vitamin C deficiency.
What is the primary function of iron in the body?
Oxygen transport.
Iron is an essential component of:
Hemoglobin, Myoglobin, and Cytochromes.
Where is the majority of iron stored in the body?
Hemoglobin
How does iron contribute to immune function?
Enhances macrophage activity, T-cell proliferation, and bacterial growth restriction.
Cytochrome enzymes containing iron are critical for:
Electron transport chain (ATP production).
What is the main regulatory hormone for iron homeostasis?
Hepcidin
What happens to hepcidin levels when iron levels are high?
Hepcidin increases to block iron absorption.
How does hepcidin regulate iron?
Blocks ferroportin to prevent iron release into circulation.
What condition decreases hepcidin levels?
Hypoxia.
Transferrin saturation is a marker of:
Iron stores, iron deficiency, and iron overload
Ferritin primarily functions as:
An iron storage protein.
Hepcidin decreases plasma iron levels by acting on which protein?
Ferroportin
Which factor increases hepcidin production?
Iron overload.
What decreases hepcidin production?
Erythropoietic stimulation.
The transferrin receptor is critical for iron uptake because:
It binds transferrin–iron complexes for receptor-mediated endocytosis.
Which condition is associated with iron overload?
Hemochromatosis
What gene mutation is linked to hereditary hemochromatosis?
HFE gene.
Which lab test best reflects iron stores?
Ferritin
Iron-deficiency anemia is characterized by:
Microcytic hypochromic red blood cells
Common causes of iron-deficiency anemia:
Chronic blood loss, pregnancy, poor diet
What is the primary treatment for iron-deficiency anemia?
Iron supplementation.
Which test differentiates iron-deficiency anemia from anemia of chronic disease?
Ferritin
What are the complications of iron overload?
Liver cirrhosis, diabetes, cardiomyopathy
What is the best treatment for hereditary hemochromatosis?
Phlebotomy
What is a major cause of secondary iron overload?
Repeated blood transfusions.
A 45-year-old man presents with fatigue, joint pain, and bronze skin pigmentation. Lab tests show high ferritin, high transferrin saturation, and low hepcidin. What is the most likely diagnosis?
A: Hereditary Hemochromatosis.
Next Steps:
* Confirm HFE gene mutation.
* Start phlebotomy therapy.
