Pathoma 5. Flashcards
(103 cards)
Iron absorption occurs in the?
duodenum
Iron consumed in two dietary forms
Heme form(meat) and non–heme form(vegetables) -heme form more readily absorbed
Describe transport and storage of iron
1.) Absorption of iron occurs via enterocytes and their transporters. 2.) Transport into bloodstream occurs through ferroportin(iron MUST be bound while in blood to prevent free radical) 3.) Iron is then bound to transferrin in bloodstream where it is delivered to liver and bone marrow. 4.) Stored intracellular iron is bound to ferritin, which prevents free radical formation
Causes of Microcytic Anemia
Iron deficiency Anemia, Anemia of Chronic Disease, Sideroblastic Anemia, Thalassemia
Anemia of Chronic Disease
Iron locked away in macrophages
Most common nutritional deficiency?
Iron deficiency
Most important regulatory step in iron uptake?
Ferroportin – transport of iron into blood. On enterocyte.
TIBC
measures amount of transferrin in blood
Serum Iron
Measure of iron in blood(this iron WILL be bound to transferrin)
% Saturation
percentage of transferrin bound to iron
Serum Ferritin
amount of iron bound in liver and macrophages
Lab findings in first stage of iron deficiency
Storage iron is depleted - This causes decreased ferritin because iron is being picked up from the liver/macrophage. Also causes increased TIBC because liver makes more transferrin to try and pick up more iron.
Lab findings in second stage of iron deficiency
Serum iron is depleted - Serum iron goes down(duh). % Sat of transferrin also goes down.
Lab findings in third stage of iron deficiency
Normocytic anemia - Bone marrow LIKES pretty red blood cell, but lacks the iron to make enough of them. Therefore it makes less, BUT they are normocytic!
Lab findings in fourth stage of iron deficiency
Microcytic, hypochromic anemia
clinical features of iron deficiency
Anemia, Koilonychia, and Pica
Describe RDW and FEP in Iron deficiency anemia…
Increased RDW due to initial normocytic RBC’s mixing with microcytic, so the distribution of width is larger than normal. - FEP, increased free erythrocyte protoporphyrin is due to the lack of heme to bind to it.
Plummer–Vinson syndrome
Esophageal webs, atrophic glossitis(smooth tongue), and iron deficiency anemia
Patient presents with anemia, dysphagia, beefy red tongue.
Plummer–Vinson syndrome - esophageal webs, atrophic glossitis (smooth tongue), iron deficient anemia
Anemia of Chronic Disease pathophys
chronic disease ––> chronic inflammation ––> increased acute phase reactants(Hepcidin): Hepcidin sequesters iron in storage sites, preventing transfer of iron from macrophages to erythroid precursors. In addition, chronic disease suppresses EPO production
Lab findings in anemia of chronic disease
increased ferritin, decreased TIBC, decreased serum iron, decreased %sat, increased FEP. Increased FEP – Heme = Fe+ + Protoporphyrin. Since iron is reduced, but protoporphyrin is normal, there is elevated protoporphyrin
Sideroblastic Anemia pathophys
defective protoporphyrin synthesis. Heme = Iron + Protoporphyrin, If protoporphyrin is bad, then Heme is bad, which means RBC’s are going to be smaller
Rate limiting step in protoporphyrin synthesis?
Conversion of Succinyl–CoA to Aminolevulinic Acid(ALA) via Aminolevulinic Acid Synthetase(ALAS) - REQUIRES Vitamin B6(pyridoxine)
Final step of protoporphyrin synthesis? Where does it occur?
Ferrochelatase atatches protoporphyrin to iron to make heme. This occurs in mitochondria.