Microcytic Anemias Flashcards
What is the cause of microcytic anemias?
Decreased production of hemoglobin
Why is microcytosis seen in the presence of decreased hemoglobin?
RBCs must divide an extra time in order to try and maintain hemoglobin concentration, causing microcytic anemia
What is the composition of heme?
Iron and protoporphyrin
What are the 4 microcytic anemias?
1) iron deficiency anemia
2) anemia of chronic disease
3) sideroblastic anemia
4) thalassemia
Anemia due to decreased levels of iron…
Iron deficiency anemia
Where does the absorption of iron occur?
Duodenum
How is iron transported across the cell membrane into the blood?
Enterocytes transport iron using ferroportin
What substance is responsible for the transport of iron in the blood?
Transferrin
Where does transferrin transport iron for storage?
To the liver and bone marrow macrophages
What is stored intracellular iron bound to?
Ferritin
What does the storage of iron bound ferritin prevent?
Free radical formation via the Fenton reaction
What are the 4 laboratory measurements used to evaluate iron status in patients?
1) serum iron
2) Total iron-binding capacity (TIBC)
3) % saturation
4) Serum Ferritin
What serum iron measuring?
Measure of iron in the blood
What is total iron-binding capacity (TIBC) measuring?
Measure of transferrin molecules in the blood
What is % saturation of iron measuring?
% of transferrin molecules that are bound by iron (normal is 33%)
What is serum ferritin measuring?
Iron stores in macrophages and the liver
What is the most common cause of microcytic anemia seen in infants?
Breast-feeding—human milk is low in iron
What is the most common cause of microcytic anemia in children?
Poor diet
What is the most common cause of microcytic anemia in male adults ages 20-50?
Peptic ulcer disease
What is the most common cause(s) of microcytic anemia in female adults ages 20-50?
Menorrhagia
Pregnancy
What is the most common cause(s) of microcytic anemia in the elderly?
Colon polyps/carcinoma in Western world
Hookworm in developing world
Malnutrition, malabsorption and gastrectomy are all causes of why type of anemia?
Microcytic anemia
What is the first stage of iron deficiency?
Storage iron is depleted
What are the laboratory values, with respect to ferritin and TIBC, in the first stage of iron deficiency?
Ferritin: decreased
TIBC: increased
NOTE: If ferritin is decreased then TIBC will be increased, ALWAYS
What is the second stage of iron deficiency?
Serum iron is depleted
What are the laboratory values, with respect to serum iron and % saturation of iron, in the second stage of iron deficiency?
Serum iron: decreased
% Saturation: decreased
What is the third stage of iron deficiency?
Normocytic anemia
Why is normocytic anemia seen in the third stage of iron deficiency?
The bone marrow is making fewer, but normal sized RBCs
What is the fourth stage of iron deficiency?
Microcytic, hypochromic anemia—bone marrow is making smaller and fewer RBCs
What are the clinical features of iron deficiency?
Anemia
Koilonychia
Pica
What are the laboratory findings seen with iron deficiency anemia with respect to the following: RBCs, Ferritin, TIBC, serum iron, % saturation, and free erythrocyte protoporphyrin (FEP)?
RBCs: microcytic and hypochromic with increased red cell distribution width Ferritin: decreased TIBC: increased Serum iron: decreased % Saturation: decreased FEP: increased
What is the treatment for iron deficiency microcytic anemia?
Supplemental iron—ferrous sulfate
Iron deficiency anemia with esophageal web and atrophic glossitis that presents as anemia, dysphagia, and beefy-red tongue…
Plummer-Vinson syndrome
