Chapter 3 Essential Hematology (Hypochromic Anemias) Flashcards
Iron deficiency is the most common and important cause of which type of anemia?
Microcytic hypochromic anemia
Which 2 lab values are reduced in microcytic hypochromic anemias?
- MCV: mean corpuscular volume
2. MCH: mean corpuscular hemoglobin
What are the 2 major differential diagnoses in microcytic hypochromic anemias?
- Thalassemia
2. Anemia of chronic disease
What are the 4 possible causes of microcytic hypochromic anemia?
- Lack of iron (iron deficiency)
- Lack of iron release from macrophages to serum (anemia of chronic inflm/disease)
- Failure of protoporphyrin synthesis (sideroblastic anemia)
- Failure of globin synthesis (thalassemia)
Lead inhibits the synthesis of what?
Heme and globin
How many atoms of iron can transferrin hold?
Up to 2
T or F. Transferrin is recycled.
T
What happens to RBCs at the end of their life and the iron they contained?
Broken down by macrophages and the iron is released from hemoglobin. The iron then enters the plasma and provides most of the iron bound to transferrin.
How is iron stored in macrophages?
Ferritin and hemosiderin
Is ferritin water soluble?
Yes
What is apoferritin?
The outer protein shell of ferritin that consists of 22 subunits and an iron-phosphate-hydroxide core.
Is apoferritin visible by light microscopy?
No
How many atoms of iron can one molecule of apoferritin bind?
4,000-5,000
Most of the iron in the body is contained in what?
In circulating hemoglobin. It is reutilized for hemoglobin synthesis after the red cells die.
Iron in macrophages is transferred to plasma transferrin and then transferred to what?
Bone marrow erythroblasts
T or F. Iron absorbed from the diet is normally just sufficient to make up for iron loss.
T: about 1 mg is absorbed to balance the 1 mg lost in urine, feces, nails, hair, and skin.
Is hemosiderin water soluble?
No: it is an insoluble protein-iron complex.
What is hemosiderin derived from?
Partial lysosomal digestion of aggregates of ferritin molecules.
What stain must be used to see hemosiderin on light microscopy?
Prussian blue
What form is iron in when in ferritin and hemosiderin?
Ferric form (Fe3+)
Describe the process of iron mobilization when bound to ferritin and hemosiderin.
Bound in ferric form. Reduced to ferrous form for mobilization (vitamin C required).
What copper-containing enzyme catalyzes the oxidation of iron to the ferric form for binding to plasma transferrin?
Ceruloplasmin
Where else is iron found in the body?
In muscle as myoglobin and also in most cells in iron-containing enzymes (cytochromes, succinic dehydrogenase, catalase, etc.).
T or F. Iron in tissue is less likely to become depleted than the iron in hemosiderin, ferritin, and hemoglobin in states of iron deficiency.
T: but some reduction of heme-containing enzymes may occur.