Iron deficiency Flashcards
Is heme iron or elemental iron absorbed more efficiently?
-heme iron
Where is iron absorbed?
-duodenum
Describe the absorption of elemental iron.
- Mostly in form of Fe3+ and must be reduced to Fe2+
- DMT1 transport Fe2+ at the apical side
- iron can be stored in intestinal cells as ferritin
- or can be exported as Fe2+ by FPN1 (ferroportin) on basolateral side
- Fe2+ is oxidized to Fe3+ to bind to transferrin (Tf) to circulate in the body
What is responsible for a majority of the iron available for erythropoiesis?
- macrophage recycling: macrophages in spleen engulf old or damaged RBCs and release Heme from Hb. Heme oxygenase releases iron from heme
- iron recovered from heme may be stored as ferritin or exported to plasma by FPN1 where it is oxidized to +3, binds Tf, and is available for erythropoeisis
Deficiency of ________ rapidly limits erythropoiesis.
-Fe2-Tf
Describe the process of incorporating iron into Hb.
- incorporated into erythroblasts in BM
- diferric transferrin binds transferrin receptor on erythroblast surface. It is engulfed via cathrin-coated pit, endosome at low pH dissociated Fe from receptor (which is recycled). Fe is stored as ferritin or added to heme, then joined to a2B2 to form Hb
What is the main iron regulatory protein in the body and what does it do?
- Hepcidin: 25 AA made mainly in the liver
- negative regulator of cellular iron export by binding and degrading ferroportin in enterocytes and macrophages; downregulated FPN1
- iron is trapped in enterocytes and macrophages
Who is at highest risk for iron deficiency anemia?
-infants, young children, women, elderly
2 general categories and 5 subcategories of causes of iron deficiency
- Inadequate supply: nutritional, malabsorption
2. Increased demand: blood loss, rapid growth, pregnancy
Name some things that can increase or decrease absorption of iron.
- increase: heme iron and vitamin C (facilitates ferrireduction)
- decrease: plant iron, tannins (tea, coffee), fiber, Ca2+, disrupted mucosa, achlorhydria
- *remember, take iron with OJ, not coffee
Blood losses to be aware of that can lead to iron deficiency
- Gastrointestinal (especially in adults!!): colon cancer, ulcers, gastritis (H. pylori, NSAIDs), hookworm, Meckel’s Diverticuli, hemorrhoids, vascular malformations
- menstrual: menorrhagia
- child birth
- trauma
- chronic hemoglobinuria
Signs and symptoms of iron deficiency
-pallor, weakness, fatigue, headache, irritability, angular stomatitis, pagophagia (chew ice, eat dirt), beeturia, blue sclera, koilonychia (brittle nails)
Lab evaluations for Iron Deficiency: hematological and biochemical markers.
- Hematologic: decreased Hb, decreased RBC, microcytic, increase RDW, decrease retic, often but not always have increase in platelets
- Biochem: dec. ferritin, dec. serum iron, dec. transferrin saturation, increase TIBC, increase serum transferrin R, increase free erythrocyte protoporphyrin
Rx of iron deficiency
- correct iron deficiency: give oral iron sulfate, slow release iron, parenteral iron, RBC transfusion is rarely needed
- identify and correct underlying cause of iron deficiency anemia
- prevention is preferable
Describe the body’s response to iron therapy.
- retic count rises in 3-4 days, and peaks in 5-10 days
- following retic increase, Hb rises
