Flashcards in Ch5 - 2) Microcytic anemia Deck (103)
Microcytic anemias include
(1) iron deficiency anemia, (2) anemia of chronic disease, (3) sideroblastic anemia, and (4) thalassemia.
Iron deficiency anemia is due to?
decreased levels of iron -> dec heme -> dec hemoglobin —» microcytic anemia
What is the most common type of anemia?
iron deficiency anemia
What is the most common nutritional deficiency in the world?
Lack of iron, affecting roughly 1/3 of world's population
Iron is consumed in what forms?
heme (meat-derived) and non-heme (vegetable-derived) forms
Absorption of iron occurs in the?
duodenum, Enterocytes have heme and non-heme (DMT1) transporters; the heme form is more readily absorbed
How do enterocytes transport iron?
across the cell membrane into blood via ferroportin
How does transferrin transports iron?
in the blood and delivers it to liver and bone marrow macrophages for storage.
Stored intracellular iron is bound to what?
ferritin, which prevents iron from forming free radicals via the Fenton reaction
Laboratory measurements of iron status
1) serum iron 2)TIBC 3) % saturation 4) Serum ferritin
What does the serum iron measure?
Serum iron is a measure of iron in the blood
What does total iron-binding capacity (TIBC) measure?
transferrin molecules in the blood
What does % saturation of iron measure?
percentage of transferrin molecules that are bound by iron (normal is 33%)
What does serum ferritin measure?
reflects iron stores in macrophages and the liver
What is iron deficiency is usually caused by?
dietary lack or blood loss
What is iron deficiency is usually caused by in infants?
breast-feeding (human milk is low in iron)
What is iron deficiency is usually caused by in children?
What is iron deficiency is usually caused by in adults?
(20-50 years old)—peptic ulcer disease in males and menorrhagia or pregnancy in females
What is iron deficiency is usually caused by in elderly?
colon polyps/carcinoma in the Western world; hookworm (Ancylostoma duodenale and Nieator americanus) in the developing world
What are some other causes for iron deficiency?
malnutrition, malabsorption, and gastrectomy (acid aids iron absorption by maintaining the Fe2+ state, which is more readily absorbed
What are the stages of iron deficiency?
1. Storage iron is depleted— decreased serum ferritin; increased TIBC (transferrin) 2. Serum iron is depleted— dec serum iron; dec % saturation 3. Normocytic anemia—Bone marrow makes fewer, but normal-sized, RBCs 4. Microcytic, hypochromic anemia—Bone marrow makes smaller and fewer RBC's
The initial stage of iron deficiency results in what type of anemia?
normocytic anemia b/c the bone marrow's initial response is to make as many normal RBC's as possible
what are the clinical features of iron deficiency
anemia, koilonychia, and pica.
Laboratory findings for iron deficiency include?
microcytic, hypochromic RBCs with increased red cell distribution width increased RDW, 2. decreased ferritin; inc TIBC; dec serum iron; dec % saturation 3. inc Free erythrocyte protoporphyrin (FEP
What is FEP?
free erythrocyte protoporphoryin - decreased Fe means less protoporphorin is bound producing heme.
Why do you have increased RDW in iron deficiency?
initial response of bone marrow is to produce as many normal RBC's as possible, after the anemia progresses it produces small RBC's - varying sizes means increased RDW
What is RDW?
red blood cell distribution width, measures the spectrum of size of the RBC's
What does a low RDW mean?
all of the red blood cells have the same size
What does a high RDW mean?
RBC's have diffent sizes