Topic 4: Anemias Putting it Together

Question 1

what lab values of a CBC should you look at if you suspect someone has anemia?

Answer 1

hemoglobin then mean cell volume (MCV)

low Hb = anemia

MCV tells us if anemia is microcytic, normocytic or macrocytic

Question 2

which anemias are microcytic?

Answer 2

1. iron-deficiency anemia
2. thalassemia
3. sometimes anemia of chronic disease (ACD)

Question 3

which anemias are macrocytic?

Answer 3

1. megaloblastic

2. non-megaloblastic anemia

Question 4

what deficiency causes megaloblastic anemia?

Answer 4

B12/folate deficiency

Question 5

what will the blood smear of a megaloblastic anemia look like?

Answer 5

it will show big oval macrocytes and hypersegmented neutrophils

Question 6

what will the blood smear of a no-megaloblastic anemia look like?

Answer 6

Non-megaloblastic anemias are still macrocytic, but they don’t have the crazy megaloblastic changes, so we won’t see hypersegmented neutrophils in the blood

alcohol or myelodysplasia can cause anemia that falls into this category

Question 7

what two things can induce non-megaloblastic anemia?

Answer 7

1. alcohol
2. myelodysplasia

clonal disorder where all the cells arise from one initial bad cell that can sometimes turn into leukemia

Question 8

what’s a common characteristic of normocytic anemias?

Answer 8

they’re usually hemolytic!

the red blood cells (RBSs) are getting busted open for some reason

Question 9

If we have a normocytic anemia, what lab test will tell us whether the bone marrow is responding appropriately?

Answer 9

reticulocyte count

most patients with hemolytic anemias have a robust bone marrow response to the anemia

the erythroblasts are dividing like crazy and maturing into RBCs to send into the periphery so there’s an increased reticulocyte count

When the bone marrow is responding to the anemia by creating more RBCs, the reticulocyte count goes up. If the bone marrow isn’t working well, the reticulocyte count will be normal or decreased.

Question 10

what is aplastic anemia?

Answer 10

the bone marrow is basically making nothing—no RBCs, no white cells, no platelets

the blood reflects this by being pancytopenic

Question 11

what CBC value is used to differentiate between iron-deficiency anemia and thalassemia

Answer 11

both are microcytic anemias and blood smears can look similar so use the RBC distribution width (RDW) = measures how much the cells vary in size

IDA: RDW is elevated because as each new wave of iron-starved RBCs reaches the blood, it is smaller than the last wave so there’s a bunch of newer little RBCs and then normal sized older RBCs

thalassemia: RDW is normal because thalassemia is not an evolving thing, like IDA. You’re born with the defect, and every time you make a new RBC, you’re dealing with the same defect. So the cells are all the same size

Question 12

What two CBC parameters help you differentiate between IDA and thalassemia? (aka microcytic anemias)

Answer 12

1. RDW
2. RBC count

RDW (increased in IDA, normal or low in thalassemia) and RBC count (decreased in IDA, increased in thalassemia)

Question 13

how can the RBC count help you differentiate between IDA and thalassemia microcytic anemias?

Answer 13

IDA: low RBC count because you don’t have enough iron to make red blood cells, so the count goes down

thalassemia: increased RBC count because it may be the bone marrow’s way of dealing with the lack of globin chains – maybe it makes smaller, but more numerous, RBCs

Question 14

how can you differentiate between IDA and thalassemia on a blood smear?

Answer 14

1. thrombocytosis, which is often present in IDA, but not in thalassemia;
2. elliptocytes (or cigar-shaped cells, if you like a smooth Cohiba), which are
   present in IDA but not thalassemia
3. basophilic stippling, which may be seen in thalassemia but not in IDA

Question 15

what kind of anemia is anemia of chronic disease?

Answer 15

ACD can be normocytic, but it can be microcytic, too

Question 16

how do you differentiate between ACD and IDA?

Answer 16

iron studies

1. serum iron is low in both so that doesn’t help
2. low ferritin = IDA for sure

normal/high ferritin = probably ACD but it could still be IDA because ferritin is an acute phase reactant, it will go up when there are things like inflammation around

3. TIBC is increased in IDA and normal/decreased in ACD
   * ferritin = body’s iron stores

Question 17

How do we use the ferritin to distinguish IDA from ACD?

Answer 17

ferritin should be low in IDA and normal to high in ACD.

however, ferritin is an acute reactant – so a normal or even increased ferritin does not rule OUT IDA.

Question 18

what RBC size category of anemias do hemolytic anemias usually fall into?

Answer 18

usually normocytic anemias

Question 19

how can you tell if a patient is actually hemolyzing their RBCs?

Answer 19

1. elevated bilirubin
2. elevated lactate dehydrogenase
3. decreased free haptoglobin levels
4. hemoglobin in the serum or urine if hemolysis is intravascular
5. increased reticulocytes in the blood smear
6. nucleated RBCs in blood smear if there’s severe anemia

Question 20

how do bilirubin levels change during hemolytic anemia?

Answer 20

usually elevated

you’re dumping all that heme into the blood, and it’s got to be broken down into bilirubin

If it’s a rip-roaring hemolysis, the liver will not be able to keep up, and we’ll see an unconjugated hyperbilirubinemia

Question 21

how do lactate dehydrogenase levels change during hemolytic anemia?

Answer 21

usually elevated

LDH is just an enzyme that’s present in a lot of cells, including RBCs

if you bust the RBCs open, LDH leaks out and can be measured in the blood

Question 22

how do FREE haptoglobin levels change during hemolytic anemia?

Answer 22

decreased haptoglobin

haptoglobin carries free hemoglobin

so as more and more hemoglobin is dumped into the blood, the amount of free (unbound) haptoglobin decreases

Question 23

how do hemoglobin levels in the serum and urine change during hemolytic anemia?

Answer 23

might also see hemoglobin in the serum (hemoglobinemia) or urine (hemoglobinuria) if the hemolysis is intravascular

Question 24

how can you look at a blood smear to tell if it’s a hemolytic anemia?

Answer 24

look at the blood smear for presence of reticulocytes, and—if it’s a particularly severe anemia—nucleated red blood cells

reticulocyte count should go up assuming the bone marrow is working properly

in severe cases of anemia, the marrow lets nucleated RBCs leave home early to make room for more cells to divide

Question 25

what are the two categories of hemolytic anemias?

Answer 25

autoimmune hemolytic anemia

non-immune hemolytic anemia

Question 26

what test would tell you if it’s an autoimmune hemolytic anemia or non-immune hemolytic anemia?

Answer 26

direct antiglobulin test (DAT)

looks to see if the patient’s RBCs are coated with antibody

if it’s positive, it’s probably an autoimmune hemolytic anemia

if it’s negative, it’s one of the (many) non-immune hemolytic anemias

Question 27

what shows up in the blood smear of non-immune hemolytic anemias that can help differentiate them?

Answer 27

1. schistocytes, in microangiopathic hemolytic anemia
2. spherocytes, in hereditary spherocytosis
3. bite cells, in G6PD deficiency
4. sickle cells in sickle cell anemia

Question 28

how can macrocytic anemias often be differentiated?

Answer 28

by looking for megaloblastic changes on a blood smear

Question 29

how can microcytic anemias often be differentiated?

Answer 29

can be differentiated using:

1. the RDW and RBC count for IDA and thalassemia
2. iron studies for IDA and ACD
3. blood smear (look for clues like elliptocytes)

Question 30

what’s in the blood smear of a microangiopathic hemolytic anemia that differentiates it from the other hemolytic anemias?

Answer 30

schistocytes

Question 31

what’s in the blood smear of hereditary spherocytosis that differentiates it from the other hemolytic anemias?

Answer 31

spherocytes

Question 32

what’s in the blood smear of a G6PD deficiency anemia that differentiates it from the other hemolytic anemias?

Answer 32

bite cells

aka RBC with semicircular “bites” at the edges

Question 33

what’s in the blood smear of sickle cell anemia that differentiates it from the other hemolytic anemias?

Answer 33

sickle cells

Question 34

a woman has low Hb, low MCV, high RDW, low RBC count, and high platelets. Blood smear has increased anisocytosis and elliptocytes. What anemia does she have?

Answer 34

iron-deficiency anemia

low Hb = anemia

low MCV = microcytic anemia

increased RDW = iron-defieincy

a female of childbearing age with a microcytic anemia, iron-deficiency anemia due to heavy periods or multiple pregnancies is the presumed diagnosis

Question 35

woman has low Hb, high MCV, normal RDW, low RBC count. Blood smear has hyperhsegmented neutrophils. What anemia does she have?

Answer 35

low Hb = anemia

high MCV = macrocytic anemia

hypersegmented neutrophils = megaloblastic anemia

Question 36

patient is jaundiced. Low Hb, normal MCV, normal RDW, low RBC count, normal WBC, normal platelets. Blood smear shows RBCs with semicircular bites at the edges. What anemia does he have?

Answer 36

G6PD deficiency

Question 37

patient has petechiae across both legs and trunk. low Hb, normal MCV and RDW. low RBC count, WBC, and platelets. Blood smear shows decreased number of normal looking RBC and few WBC and platelets. what anemia does she have?

Answer 37

aplastic anemia

CBC shoes a decreased in all three cell lines: RBC, WBC, and platelets