Disorders of RBCs Flashcards
Where does hematopoiesis occur in the fetus at 3 weeks, 3 months, and the third trimester
At 3 weeks, in the yolk sac
3 months, kidney
3rd trimester, occurs in the bone marrow
What type of bone has hematopoietic marrow and where is it contained?
Spongy bone in the intratubular space
What is the formula to determine cellularity of the bone marrow?
100%-age
What is erythropoietin and where is it produced?
A growth factor that stimulates differentiation of red blood cells, made in the kidney
What is the name for the cell in the last stage of RBC production in the bone marrow?
Orthochromatic erythroblast
A reticulocyte will show what kind of staining? Due to?
Polychromatic staining due to RNA machinery
What is hematocrit?
The volume of red blood cells per unit of blood expressed as a percentage
What are the two ways of classifying anemia?
Red cell morphology and underlying mechanism
What are the two mechanisms for anemia?
Increase in RBC loss or decrease in production
Where does RBC destruction occur in extravascular hemolysis?
Spleen and liver
What causes intravascular hemolysis, is it more or less common than extravascular?
mechanical forces or biological agents, less common
What substance levels change in intravascular hemolysis?
Increased lactate dehydrogenase and decreased haptoglobin
What is immunohemolytic anemia?
When there is premature destruction of RBCs due to antibodies binding to them
What test is used to determine one has hemolytic anemia?
The Coombs test
What are the two types of immunohemolytic anemia?
Warm and cold antibody
In the warm type what Ig is present? At what temperature are they active?
IgG, 37 degrees C
What is the primary cause of the warm type?
Idiopathic
Which drugs can cause the warm type?
Penicillin and alpha-methyldopa
How do you treat the warm type?
Intravenous Ig, prednisone, and splenectomy as a last resort
In the cold type, what Ig is present? Describe the mechanism for this disease?
IgM, the IgM causes C3b to bind to the RBCs. When the RBCs reach warmer areas of the body the IgM is lost but the C3b remains which activates the complement system. The RBCs are then destroyed in the spleen and liver
Acute and chronic cases of the cold type are associated with?
Acute with infectious agents, chronic with lymphoma or they can be idiopathic
What are the sites for bone marrow biopsy?
The tibia in neonates and the sternal crest in adults
What is the most common hereditary hemolytic anemia in the world?
Sickle cell anemia
What causes sickle cell?
A point mutation on the 6th position of the beta globin gene substituting a valine for a glutamate
Autosplenectomy as seen in sickle cell leads to increased susceptibility to infection by?
Encapsulated organisms
What is the most common cause of death in children with sickle cell?
Septicemia and meningitis