Lecture 2: Approach to the Adult Patient with Anemia (enochs) Flashcards
Define erythropoiesis.
The production of RBCs.
what is the four steps of Erythropoiesis
Low O2 situations (hypoxic)
EPO stimulation
RBC proliferation and maturation
Reticulocyte release
What is the progenitor cell of an RBC?
Common myeloid progenitor cell.
The binding of what to what induces RBC maturation?
Binding of EPO to marrow erythroid precursors (proerythroblasts)
What are folate and Vit B12 specifically needed for in RBCs?
Proliferation and continual maturation.
What does a lack of folate and B12 cause?
Overly large RBCs that are immature.
What is iron specifically needed for in RBCs?
Accumulation of Hgb.
What does a lack of iron cause?
Small RBCs
When is an RBC smallest and largest?
Largest when it is immature.
Smallest when it is fully matured.
What is a reticulocyte? Describe it.
An immature RBC.
It is slightly bluer than a RBC and also lacks the biconcave nature of an RBC.
What is unique about a reticulocyte vs an RBC?
It contains RNA, which is not absorbed until it becomes a fully mature RBC.
How much of our blood is typically made of reticulocytes?
0-1.5%.
This is the retic count.
In what situations would I expect retic count to increase?
Active bleeds.
Consistent blood loss.
What are the optimal conditions for erythropoiesis?
Normal EPO production
Normal erythroid marrow function
Adequate Hgb accumulation
What is anemia defined by?
A reduction in one OR more of the major RBC measurements.
Hgb, Hct, or RBC.
What are the two approaches to anemia?
Kinetic approach
Morphologic approach
Define kinetic approach to anemia.
Addressing the mechanism responsible for the fall in Hgb concentration.
Define morphologic approach to anemia.
Categorizing anemia based on alterations in RBC characteristics and reticulocyte response.
What 3 mechanisms cause anemia?
Decreased RBC production
Increased RBC destruction (hemolysis)
Blood loss (Most COMMON CAUSE)
When we are at steady state, how many RBCs are being destroyed and produced?
About 1%. They are are directly related.
What can cause a reduction in RBC production?
Lack of nutrients (iron, B12, folate)
Bone marrow disorders
Bone marrow suppression
Low levels of trophic hormones (decrease stim for RBC production such as EPO)
Acute/chronic inflammation (affects iron conc, reduces EPO and decreases RBC life span)
What nutrients cause a reduction in RBC production?
Iron, Folate, and B12.
How do bone marrow disorders and bone marrow suppression reduce RBC production?
They reduce the production of the RBC precursors.
In what chronic condition is EPO commonly reduced?
Chronic renal failure.
How does acute/chronic inflammation affect RBC production?
Iron concentration is affected.
EPO reduced.
RBC life span decreased.
What 3 conditions can cause increased RBC destruction?
Inherited hemolytic anemias
Acquired hemolytic anemias
Hypersplenism
What are the two major inherited hemolytic anemias?
Sickle cell
Thalassemia major
What are the 4 conditions that can cause blood loss?
Gross blood loss (aka visible blood loss)
Occult blood loss (aka hidden blood loss)
Iatrogenic blood loss (aka healthcare-induced)
Underappreciated menstrual blood loss
What secondary conditions often results when you lose a lot of RBCs?
Iron deficiency, which further exacerbates anemia.
What happens to retic count in an active bleed? Decreased RBC production? Increased RBC destruction?
Increased in an active bleed.
Decreased in decreased RBC production.
Increased in increased RBC destruction.
How is the morphologic approach to anemia classified?
RBC indices.
MCV, MCH, MCHC
How is MCV classified in anemia?
Microcytic, normocytic, macrocytic.
What does reticulocytosis do to MCV?
Increase it, since reticulocytes are larger than regular RBCs.
How is MCH classified in anemia?
Hypochromic, normochromic, hyperchromic.
What are the main causes of a macrocytic anemia?
Folate and B12 deficiency
Drugs that interfere with nucleic acid synthesis (lack of RNA degredation)
Abnormal RBC maturation
Alcohol abuse (folate deficiency)
Liver disease (lipid deposits on RBC, increasing SA)
How does a folate and B12 deficiency cause macrocytic anemia?
Inadequate proliferation of erythroblasts, which result in giant, immature RBCs.
What are the main causes of a microcytic anemia?
Iron deficiency
Alpha/beta thalassemia minor
What is microcytic anemia often associated with?
Low MCHC due to low Hgb content.