Ch5 - 4) Normocytic anemia Flashcards
What is normocytic anemia?
Anemia with normal-sized RBCs (MCV = 80-100 um3)
What is normocytic anemia due to?
increased peripheral destruction or underproduction
How do you distinguish between the two etiologies of normocytic anemia?
Reticulocyte count
What are reticulocytes?
Young RBCs released from the bone marrow,
How are reticulocytes identified?
They appear on blood smear as larger cells with bluish cytoplasm (due lo residual RNA)
What is the normal reticulocyte count (RC)?
1-2%.
What is the RBC lifespan?
it is 120 days;
What is the turnover of RBC’s?
each day roughly 1-2% of RBCs are removed from circulation and replaced by reticulocytes.
How does a properly functioning marrow respond to anemia?
by increasing the RC to >3%.
Is RC reliable in anemia?
RC is falsely elevated in anemia
Why is RC falsely elevated in anemia?
It is measured as a percentage of total RBCs; decrease in total RBCs falsely elevates percentage of reticulocytes.
How is RC corrected?
By multiplying reticulocyte count by Hct/45.
What does a corrected RC count > 3% indicate?
good marrow response and suggests peripheral destruction.
What does a corrected RC count < 3% indicate?
poor marrow response and suggests underproduction.
What is peripheral vascular destruction divided into?
Divided into extravascular and intravascular hemolysis;
What does peripheral vascular destruction result in?
both result in anemia with a good marrow response.
Extravascular hemolysis involves what?
RBC destruction by the reticuloendothelial system (macrophages of the spleen, liver, and lymph nodes).
What is the role of macrophages in extravascular hemolysis?
consume RBCs and break down hemoglobin
What do macrophages break down globin into?
globin is broken down into amino acids.
What is heme broken down into?
iron and protoporphyrin; iron is recycled.
In the reticuloendothelial system what is protoporphyrin broken down into?
unconjugated biliruhin, which is bound to serum albumin and delivered to the liver for conjugation and excretion into bile.
What does the clinical and laboratory findings include?
Anemia with splenomegaly, jaundice due to unconjugated bilirubin, and increased risk for bilirubin gallstones
When would marrow hyperplasia occur with extravascular hemolysis?
Occurs with corrected reticulocyte count > 3%
What does intravascular hemolysis involve?
The destruction of RBCs within vessels.
What are the clinical and laboratory findings for intravascular hemolysis?
1) Hemoglobinemia. 2) Hemoglobinuria 3) Hemosiderinuria 4) Decreased serum haptoglobin
Why is there hemosiderinuria in intravascular hemolysis?
Renal tubular cells pick up some of the hemoglobin that is filtered into the urine and break it down into iron, which accumulates as hemosiderin; tubular cells are eventually shed resulting in hemosiderinuria.
