Lecture 5: Evaluation of Erythrocytes: RBC Indices

Question 1

MCHC =

Answer 1

mean cell hemoglobin concentration. = (Hb/HCT) x 100 or (Hb/RBC * MCV) x 1000

Question 2

increased MCV indication of

Answer 2

increased regenerative response = (Hct/RBC count) x 10

Question 3

Which has higher avg. MCV: dog or cat?

Answer 3

dog (70 fL vs. 45 fL in cats)

Question 4

What can falsely increase MCHC?**

Answer 4

hemolysis Heinz bodies and lipemia.

Question 5

T/F: MCV increases slower than reticulocyte counts in response to hemolytic anemia

Answer 5

T

Question 6

T/F: MCV may not increase outside the reference range in response to hemorrhage

Answer 6

T

Question 7

macrocytosis is assoc. with what type of anemia?

Answer 7

regenerative anemia

Question 8

spurious macrocytosis

Answer 8

autoagglutination of erythrocytes. Occurs with prolonged blood storage or persistent hypernatremia (elevated Na in blood)

Question 9

possible causes of microcytosis in animals (5)

Answer 9

• chronic Fe deficiency: causes microcytic hypochromic anemia**
• portosystemic shunts
• anemia of inflammatory disease
• hepatic lipidosis in cats
• Japanese dog breeds without anemia

Question 10

What does microcytic mean?

Answer 10

low MCV

Question 11

portosystemic shunt will normally cause what form of anemia?

Answer 11

microcytic normochromic anemia (decreased bloodflow to liver –> RBCs not formed correctly)

Question 12

chronic inflammatory dz will normally cause what form of anemia?

Answer 12

normocytic normochromic. CAN be microcytic

Question 13

T/F: anemia of chronic inflammatory disease is usually mild

Answer 13

T

Question 14

Greyhounds have higher/lower amount of Hct than other dog breeds

Answer 14

higher. They make good blood donors

Question 15

what can cause spurious microcytosis?

Answer 15

• platelets counted in erythrocytes histogram in severely anemic patients
• persistent hyponatremia (lower than normal salt in blood plasma) in dogs??

Question 16

Things that can cause high MCHC

Answer 16

• intravascular hemolysis
• in vitro hemolysis
• Heinz bodies within erythrocytes
• Lipemia
• Erythrocyte agglutination in electronic cell counters

Question 17

Low or high MCHC in chronic Fe deficiency anemia?**

Answer 17

low

Question 18

What can cause low MCHC?

Answer 18

• regenerative anemia
• chronic Fe deficiency anemia
• hereditary stomatocytosis in dogs
• Abyssinian and Somali cats with erythrocyte osmotic fragility
• persistent hypernatremia

Question 19

anisocytosis has big/small RDW

Answer 19

big

Question 20

formula for RDW

Answer 20

(SD of erythrocyte volumes/MCV) * 100

Question 21

RDW

Answer 21

Red cell distribution width. coefficient of variation of erythrocyte volumes and an electronic measure of anisocytosis

Question 22

T/F: Fe is an essential to making Hb

Answer 22

T

Question 23

T/F: we excrete 97% of the Fe we consume in feces

Answer 23

T

Question 24

What can cause increased serum iron concentrations?

Answer 24

• hemolytic anemia

- glucocorticoids in dogs and horses

Question 25

What can cause decreased serum iron concentrations?

Answer 25

- Fe deficiency - anemia of inflammatory disease (body is sequestering)*** - portosystemic shunts - glucocorticoids in cattle

Question 26

Q: Is serum iron concentration increased with iron overload?**

Answer 26

YES

Question 27

Q about anemia of chronic inflammatory disease.**

Answer 27

body has plenty of Fe but can't access it. Body is trying to hide Fe from bacteria, but ends up depriving RBCs too

Question 28

serum ferritin conc. correlates with:

Answer 28

total body iron stores

Question 29

what can cause decreased serum ferritin conc.?

Answer 29

iron deficiency

Question 30

What can cause increased serum ferritin conc?

Answer 30

- iron overload - hemolytic anemia - inflammation - histiocytic sarcoma complex - transientyl in exercising horses

Question 31

What happens when Hb gets oxidized?**

Answer 31

(Turns to Hb+3). Doesn't bind oxygen because it's already oxidized leading to methemoglobinemia

Question 32

What can cause cyanotic-appearing skin?

Answer 32

- hypoxemia with low pO2 in arterial blood | - methemoglobinemia with normal pO2 in arterial blood

Question 33

Spot test

Answer 33

put drop of blood on white paper. If it looks brown, most likely methemoglobinemia

Question 34

Causes of methemoglobinemia

Answer 34

-administration or consumption of oxidant drugs (can also cause Heinz bodies**) -hereditary erythrocyte metHb reductase deficiency (anything that can cause Heinz bodies or oxidizing problems can cause MetHb!)

Question 35

Why does MetHb cause eccentrocyte formation?

Answer 35

When Hb oxidizes, it gets sticky and sticks to one half of the cell

Question 36

clinical signs of Methemoglobinemia

Answer 36

-cyanotic skin/MM -exercise intolerance -lethargy ataxia rapid heart rate/resp. rate -coma like state In cases of toxicity, GI symptoms/SQ edema may be present