11 Microcytic Anemia
- liquid plasma at top of tube
- % occupied by red cells compared to whole = hematocrit
- MCV: mean amount of volume in RBC, not total volume
- MCHC: ratio of MCH/MCV
- MCV most important
- iron deficiency/anemia of chronic disease: both microcytic and normocytic
Microcytic Anemia
- when not enough hemoglobin, RBC precursor undergoes extra devision, smaller RBC
- histology: larger pale areas
- if any of the 3 main components deficient, anemia
- protoporphyrin: surrounds iron in heme
- loss of heme: lead poisoning, sideroblastic anemia
Iron Deficiency
- absorbed in 2 forms
- heme: iron in center of heme, found in flesh of other animals
- absorbed in duodenum
- enterocyte uptake main way of regulation
- ferroportin controls amt of iron released from duodenal cells into body
Cause
- new born babies deplete iron store from mother in 6 months of age
- loss of acid: gastrectomy/PPI
- loss most common cause
- colon cancer: very important/dangerous. Initial presentation
- unexplained iron deficiency anemia: colon cancer workup
- losing more iron than taking in
- % sat low under pregnancy/OCP use, misleading for iron deficiency anemia
- use ferritin for diagnosis in pregnancy/OCP
Pathogenesis
- 1st thing: deplete body storage
- eventually ferritin storage depleted, and serum iron begin to drop
Diagnosis
- fewer RBC produced
- everything is low
- initially make fewer RBC but maintain size
- some cells find iron to form normal amount of hemoglobin = normal in size
- other cells deficient in iron = small
- can be seen in any nutritionally caused anemia
- thalassemia: normal, deficient production of globin chain, all RBC same problem
- not enough iron around: elevated protoporphyrin levels
- hemochromatosis: iron overload
Treatment
Anemia of Chronic Diseases
- mild anemia
- severe anemia: unlikely microcytic
- rising cytokines
- RBC don't live as long
- EPO rise higher in iron deficiency anemia compared to rise in chronic disease anemia
- ferroportin lets iron out in enterocytes and macrophages
- rise in ferritin: opposite of iron deficiency
Diagnosis
- in real life: ferritin is acute phase reactant, increase not representative. Step 1, ferritin is chronic disease
- TIBC: low, total body storage is high
- hemochromatosis: iron overload
Lead Poisoning
- heme derived from succinyl coa and glycine
- inhibition of D-ala dehydratase and ferrochelatase: low Heme
- increased activity of ALA synthase: build up of D-ALA
- protoporphyrin: also used to screen iron deficiency
Symptoms
Sideroblastic anemia
- B6 co factor
- lead poisoning: underproduction of protoporphyrin
- B6 activates available ALA synthase
Diagnosis
- lead poisoning sideroblastic: can have high protoporphyrin
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