11 Microcytic Anemia

  • liquid plasma at top of tube
  • % occupied by red cells compared to whole = hematocrit

  • average RBC

  • 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

  • % sat: iron/TIBC

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

  • battery: classic

  • 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

  • DMSA aka succimer

Sideroblastic anemia

  • B6 co factor
  • lead poisoning: underproduction of protoporphyrin

  • B6 activates available ALA synthase

Diagnosis

  • lead poisoning sideroblastic: can have high protoporphyrin