Flashcards in CH5 - Red Blood Cell Disorders Deck (284)
What is Anemia?
Reduction in circulating red blood cell (RBC) mass
What does anemia present with?
signs and symptoms of hypoxia; 1. Weakness, fatigue, and dyspnea 2. Pale conjunctiva and skin 3. Headache and lightheadedness 4. Angina, especially with preexisting coronary artery disease
How is RBC mass measured?
Hemoglobin (Hb), hematocrit (Hct), and RBC count are used as surrogates for RBC mass, which is difficult to measure
Anemia is defined as what (in terms of Hb)?
Hb<12.5 g/dL in females (normal Hb is 13.5-17.5 g/dL in males and 12.5-16.0 g/dl. in females)
What is the basis for anemia classification?
Based on mean corpuscular volume (MCV), anemia can be classified as microcytic (MCV 100)
What does the MCV give you an indication of in anemia?
size of the red blood cell
Microcytic anemias are due to
decreased production of hemoglobin.
RBC progenitor cells in the bone marrow are?
large and normally divide multiple times to produce smaller mature cells (MCV = 80-100)
Microcytosis is due to?
an "extra" division which occurs to maintain hemoglobin concentration.
Hemoglobin is made of
heme and globin:
heme is composed of?
iron and protoporphyrin
A decrease in what components leads to microcytic anemia?
iron, protoporphyrin and globin
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?