5.4 Normocytic Anemia

Question 1

Normocytic anemia

• 2 categories of causes
• how to distinguish between both?

Answer 1

1. decreased RBC production
2. increased destruction
   - use reticulocyte count.

Question 2

Normal reticulocyte count

-what does elevated mean?

Answer 2

1-2%

-elevated (>3%) means properly functioning bone marrow is responding to anemia. This suggests an anemia caused by peripheral RBC destruction not not underproduction

Question 2

Normocytic anemia caused on hemolysis:

-divided into what 2 categories of causes?

Answer 2

1. extravascular hemolysis (RBC destruction by reticuloendothelial system–spleen, liver, lymph nodes)
2. intravascular–in vessels

Question 3

Pt with jaundice and gallstones:

-think what process occuring?

Answer 3

Anemia with extravascular hemolysis

• jaundice from increased unconjugated bilirubin
• bilirubin gallstones from bile supersaturated with conjugated bilirubin.

Question 4

How to correct reticulocyte count, and why?

Answer 4

In anemia, reticulocyte count is falsely elevated b/c low RBC count.

To correct, multiply reticulocyte count (%) by Hct/45 to get corrected reticulocyte count.

Question 5

Peripheral RBC destruction from intravascular hemolysis:

-clinical/lab findings (4)

Answer 5

1. decreased serum haptoglobin (‘scavenger protein’ that binds free Hb and delivers to spleen for recycle Fe)
2. hemoglobinemia (Hb leaks into blood)
3. hemoglobinuria (Hb into urine)
4. Hemosiderinuria (tubule cells pick up Hb, break it down into Fe, and then themselves shed several days later, releasing Fe)

Question 6

What lab test to distinguish btween a normocytic anemia based on peripheral RBC destruction vs underproduction?

-what values?

Answer 6

• corrected reticulocyte count.
  1. if >3%, then bone marrow is functioning properly to respond to anemia. Suggests peripheral destruction

2.

Question 7

Reticulocyte
-appearance on blood smear

-why?

Answer 7

-slightly larger than RBC, also slightly blue due to residual RNA

Question 8

In the reticuloendothelial system:

• what cells destroy RBCs?
• what happens to the components that make up RBCs?

Answer 8

Macrophages consume RBCs and break down Hb:

1. Globin is broken down into aa
2. Heme breaks down into Fe and protoporphyrin. Fe is recycled
3. protoporphyrin is broken down into unconjugated bilirubin. This binds to serum albumin and is delivered to liver, which conjugates it and then excretes it into bile.

Question 9

Anemia caused by intravascular hemolysis:

-what do you see in urine?

Answer 9

1. hemoglobinuria
2. hemosiderinuria (occurs several days after inital hemoglobinuria)

Question 11

Anemia by extravascular hemolysis:

-where are the RBCs being destroyed? (3 places)

Answer 11

Reticuloendothelial system:

1. spleen
2. liver
3. lymph nodes

Question 12

haptoglobin

Answer 12

• blood ‘scavenger’ protein that binds to free Hb (released from dead RBC) and delivers it to the spleen to recycle Fe.
• not a significant impact on ‘rescuing’ Fe

Question 13

List normocytic anemias caused by:

1. predominant extravascular hemolysis (4)
2. predominant intravascular hemolysis (4)
3. underproduction (3)

(based on pathoma)

Answer 13

1. hereditary spherocytosis

sickle cell

Immune hemolytic anemia (pathoma mistakenly puts this in intravascular)

hemoglobin C

2. paroxysmal nocturnal hemoglobinuria

G6PD deficiency

microangiopathic hemolytic anemia

malaria

3. parvovirus B19

aplastic anemia

myelophthisic process

Question 14

Normocytic anemia caused by extravascular hemolysis:

-clinical findings (4)

Answer 14

1. anemia with splenomegaly
2. jaundice (increased unconjugated bilirubin from RBC destruction in reticuloendothelial system)
3. increased risk of bilirubin gallstones (b/c of bile supersaturated with conjugated bilirubin)
4. Marrow hyperplasia (corrected reticulocyte count >3%)