Anemia- Iron Deficiency Flashcards
Define: Anemia
Anemia is defined as insufficient red cell mass to adequately deliver oxygen to peripheral tissues .
Name three common factors that cause variations in hemoglobin
- Age. Infants >Adults>Children & Menstrating Women
- Sex
- Geography
Name three measurements you can use to define the existence of anemia.
- Hematocrit
- Hemoglobin
- Red Blood Cell Count
What is reticulocyte count?
of reticulocytes/ 1000 RBC
Define Reticulocyte index
Measurement of the production of red cells and is a way to correct the reticulocyte count for red cell concentration and stress reticulocytosis. It provides a ratio of how many fold beyond baseline the production of red cells is
What is the equation for reticulocyte index?
RI = Reticulocyte Count * (Patient Hgb/ Normal Hgb) * (1 / Stress Factor)
What are the stress factors?
Stress factor = 1.5 (mild anemia > or equal to 9 gm/ dl)
- 0 (moderate anemia 6.5 - 9)
- 5 (severe
What does an RI of less than 1 mean?
Anemia indicates decreased production of reticulocytes and therefore red blood cells.
What does an RI of > 2 mean?
Anemia indicates loss of red blood cells (destruction, bleeding, etc) leading to compensatory production of reticulocytes to replace the lost red blood cells
What is the absolute reticulocyte count?
Percent of reticulocytes * the red cell count. It is helpful in determining the relevance of the reticulocyte count.
What is the normal range for reticulocyte count?
What is the normal range for absolute reticulocyte count?
0.4-1.7%
Would you find an increase of 2,3-DPG within the cells of chronic anemia or acute anemia?
Chronic. These cells have time to establish this increase which makes the dissociation of oxygen to tissues more efficient to compensate for low oxygen carrying capacity
What symptoms would you be likely to find in someone with anemia that developed acutely?
Symptoms include: Shortness of breath fatigue rapid heart rate dizziness claudication or pain with exercise pallow Physicals signs may include: tachycardia tachypnea dyspnea and pallor
Iron exists in two valence states, what are they?
Ferric (3+) and Ferrous (2+)
Is iron soluble in aqueous solutions?
Not unless bound to specific proteins or other compounds
True or False: Iron balance is controlled primarily by excretion.
False. It is controlled by absorption. There is no active mechanism for excreting iron from the body the losses are small each day.
Where is the majority of iron found in the body?
65% associated with hemoglobin
25% Primary storage as ferritin and hemosiderin
6% Myoglobin
Name two things that maintain solubility of iron while i the stomach.
- Low gastric pH
2. Gastroferrin (iron binding protein)
Where does the absorption of iron take place?
Duodenum
What is the function of duodenal cytochrome b-like protein (DCYTB)?
Where is it found?
Function: Converts ferric iron to ferrous iron through surface reductase activity
Location: Apical side of the duodenum
What is the function of DMT1?
It is a divalent metal iron transporter that transports iron into the cell.
What is ferritin?
Storage form of iron. It is a complex structure with a coat composed of 24 subunits alternating heavy (H) or light (L) chains the center of which contains 4500 atoms of Fe
What is the function of ferroportin?
Where is it found?
Function: Baso-lateral ferrous iron transporter
Location: Baso-lateral side of duodenal cell
What is hephaestin?
Enzyme located on the baso-lateral side that oxidizes iron to the ferric form allowing it to bind to apotransferrin.
Name two things that can enhance absorption of Fe.
Name two things that can inhibit absorption of Fe.
- Presence of amino acids in the duodenum
- Vitamin C- by maintaining valence state of Fe
* also erythropoietin and increased iron in the diet - Phytates
- Oxalates
Describe transferrin and its function
Transferrin is a 84kDa plasma protein produced in the liver which binds two moles of iron in the ferric form at high specificity and affinity. It is the main transporter of iron to the marrow to maturing normoblasts.
Erythocytes live for about 120 days. What happens to the iron inside the erythrocytes when they die?
Erythrocytes are removed from circulation by macrophages in the spleen which sequester the ferritin stores. Eventually the storage pool may be released from the cell and bound by transferrin again…..IT’S THE CIRCLE OF LIFE (HEY HEY) AND IT MOVES US ALLLLLLLLLLLL
What is the function of hepcidin?
It binds to ferroportin and causes its degredation
Where is hepcidin produced?
Hepcidin is a 25 amino acid peptide that is produced in the liver in response to high iron intake and inflammation
When hepcidin levels are high what happens to the levels of saturated transferrin?
Since the flow of iron from cells to plasma is decreased so to is the saturation of transferrin
Explain how iron enters the maturing normoblast.
Transferrin binds to the transferrin receptor on maturing normoblast and is inaginated via clathrin coated pits that form an endosome.
The endosome gets acidified releasing the iron from transferring
Iron exits the endosome via the divaelent metal ion transporter (DMT1)
Transferrin and receptor is brought back up to the surface and apotransferrin in released
What population is most at risk for iron deficiency anemia?
Infants and toddlers
Women (adolescent females and post-menopausal females)
What should be on the differential diagnosis when you suspect iron anemia?
- Chronic inflammation or infection
- Chronic Disease
- Thallassemia
- Sideroblastic anemias
Normalization of parameters in iron administration is slow. List in chronological order what normalizes
- Serum Iron
- Reticulocyte (3-5 Days)
- Hemoglobin (7-10 Days)
- MCV, Erythrocyte protophyrin, and RDW (because erythrocytes lifespan is 120 days)
Name three etiologies of iron overload.
- Increase in iron intake
- Increased absorption (mutation in HLA-H
- Repeated transfusions for chronic anemia
What is the role of the HLA-H gene in iron overload?
Encodes for a protein in duodenal crypt cell which acts as a cofactor for absorption leading to increased absorption
What target organs are damaged by iron overload?
- Heart
- Liver
- Endocrin
What is hemochromatosis?
A disorder that leads to increased absorption of iron
What is the treatment for hemochromatosis?
Therapeutic phlebotomy when initially diagnosed. Followed by maintenance phlebotomy periodically for the rest of their life
What causes hemosiderosis?
Transfusions
What is prescribed for iron overload caused by frequent transfusion?
Desferal or Exjade they are iron chelators
