Parts of the Erythrogram

What are the 7 components of an Erythrogram?

1. Erythrocyte Concentration

2. Hemoglobin Concentration

3. Hematocrit

4. Erythrocyte (Wintrobes) Indicies

5. Polychromasia/Reticulocytes

6. Nucleated Erythrocytes

7. Erythrocyte morphology/Inclusions/Infectious Agents

What is the difference between an Erythron and an Erythrogram?

• Erythron

  • This is all the erythroid cells (including precursors)

• Erythrogram

  • Analytic methods used to evaluate the Erythron

Erythrogram evaluates the Erythron

Define this part of the Eyrthrogram

1. Erythrocyte Concentration

It is the # of RBCs per unit of volume of blood (aka the RBC count)

Is the “Erythrocyte concentration“ a measured or calculated value?

Measured

The Erythrocyte Concentration accurately reflects the Hematocrit and the Hemoglobin concentration if the ___ and _____ are within reference limits

MCV (Mean Corpuscular Volume) and MCHC (Mean Corpuscular Hemoglobin Concentration)

Define this part of the Eyrthrogram

1. Hemoglobin Concentration

• The grams of Hemoglobin (Hgb) per 100ml of blood

Is the “hemoglobin concentration“ a measured or calculated value?

Measured

The hemoglobin concentration is a good reflection of the blood’s _____________ capacity

O2 Carrying capacity

What is unique about the measurement of Hgb?

Hgb is present with the Erythrocytes, so they have to be lysed in order to measure the Hgb

Define this part of the Eyrthrogram

1. Hematocrit (HCT)

• The percentage of blood volume filled by erythrocytes

  • Ex: in 100 mls of blood, if the HCT is 0.45 L/L then erythrocytes occupy 45ml

Is Hematocrit a measured or calculated value?

Calculated (Hct = MCV * RBC)

What are the 3 Erythrocyte Indicies?

1. Mean Cell Volume (MCV)

2. Mean Cell Hemoglobin

3. Mean Cell Hemoglobin Concentration (MCHC)

Which Erythrocyte Indicie is not commonly used, why?

• Mean Cell Hemoglobin (MCH)

  • It is very similar to MCHC and “we” prefer MCHC

What is the Mean Cell Volume (MCV)? Is it measured or calculated?

• It is the volume per average RBC

  • Essentially, it detects the variation in size/volume of RBCs

• Mesured

What is the Mean Corpuscular Hemoglobin Concentration (MCHC)? Is it measured or calculated?

• It is the cellular Hgb per average RBC

  • This also anylyzes the average ability of a cell to carry oxygen

• Calculated

  • Hgb/HCT

What is Anisocytosis?

• A condition where there is a significant variation in the size of red blood cells (RBCs)

  • This can be a variation in size or volume

  • Caused by Macrocytosis or microcytosis

What is the difference between Macrocyte and Macrocytosis?

• A macrocyte is an erythrocyte with an increased volume

• Macrocytosis is an increased concentration of Macrocytes

What is the RDW?

• Red Cell Distribution Width

  • It is the standard deviation of the MCV

What would cause an increase in the RDW (Red Cell Distribution Width)?

An increase of Macrocytes/Microcytes

What would cause an increase in the MCV (Mean Corpuscular Volume)?

• Presence of Macrocytes if normal erythrocytes/microcytes are also present

• “RBCs are larger than normal“

An increase of MCV is aka?

Macrocytosis

What are 2 conditions that can cause an Increased MCV?

1. Accelerated erythropoiesis

   1. Young RBCs are larger than mature ones, therefore, the accelerated production of erythrocytes can cause an inc in the MCV

2. FeLV

   1. FeLV can cause non-regenerative anemia in cats

   2. The bone marrow isn’t producing enough RBCs to replace the lost ones, this high inc in young RBCs leads to an increase of MCV

T/F: An increased RDW (Red Cell Distribution Width) is associtated with only Macrocytosis

False, both Macro/Micro-cytosis

Can microcytes be an incidental finding? Why or why not?

Yes, some solutions such as EDTA are hypertonic and can cause the RBCs to appear smaller, this is known as a cell shrinkage artifact

What are some causes of Decreased MCV?

1. Iron deficiency anemia

   1. The lack of Iron causes anemia, but it also causes microcytes

   2. Without the iron, the RBCs don’t develop to full size

2. Hepatic Insufficiency

   1. How?? I don’t know

3. Breed Predispositions

   1. Asian Breed Dogs

   2. Akita, Shar-peis, Jindos

4. Young Animals

What are Hypochromic erythrocytes? What types of Erythrogram disturbance do they indicate?

• RBCs with increased central pallor (whiter/clearer in the middle)

• Hypochromic Erythrocytes have a decreased Hgb

• They indicate a decreased MCHC

What are some causes of a decreased MCHC?

• Regenerative response to anemia

  • In an effort to respond to anemia the body rapidly produces more RBCs, these RBCs are large and immature and have less Hgb

  • Essentially, there is more volume (large immature RBCs) and less Hgb → Decreased MCHC

• Iron deficiency

If a decrease in MCHC is detected without microscopic evidence of hypochromasia, what is the typical cause?

Artificial cell swelling

What is the difference between a torocyte and hypochromasia?

T/F: Increased MCHC is cause for a concern

False, it is normally an artifact

What is the most common cause of increased MCV in cats?

Non-regenerative Anemia caused by FeLV

What are sources of falsely increased MCHC?

1. Cell shrinkage artifact

2. In-vitro hemolysis

3. Spectral interferences with Hgb assay

   1. Lipemic samples

   2. Heinz bodies

Is MCHC measured or calculated?

• Calculated (MCHC=Hgb/Hct)

• MCHC is the mean of the concentration of hemoglobin contained within the space of the erythrocytes

MCHC will increase when Hgb ___ and HCT ___

• Hemoglobin Increases

• Hematocrit Decreases

MCHC = (Hgb/HCT)

What are Reticulocytes/Polychromatophils? What is the difference between the two?

• Anucleate, Immature erythrocytes with stainable cytoplasmic RNA

• The difference is in the staining

  • Wright-Giemsa stain = Polychromatophils

  • New Methylene Blue = Reticulocytes

What is the lifespan of reticulocytes in Dogs vs in cats?

• Dogs

  • 1-2 days

• Cats

  • Variable (lifespan and type)

What are the 2 different types of cat reticulocytes? Which ones do we count?

1. Aggregate

   1. We count these ones

   2. Larger cells with aggregates of reticulum

2. Punctate

   1. Smaller granules, 2-6 reticulum

   2. They look like individual flakes of pepper or individual circles

What is Reticulocytosis?

An increased Reticulocyte count

What is Reticulocytosis good evidence of?

Increased Erythropoiesis

The two different types of Reticulocytes in cats can help us get an idea the timeline of erythropoiesis the animal is in. Describe the different stages

• Aggregate

  • 3-5 days post anemic event

• Punctate

  • 7-14 days post anemic event

The degree of increased polychromasia should correspond to the degree of ____________ in dogs and cattle, and to _______ ________ in cats

• Reticulocytosis

• Aggregate Reticulocytosis

How do you know that an animal has reticulocytosis?

• By calculating the Reticulocyte Percentage (RP)

• and then using the RP to calculate the reticulocyte count

  • RC = RP * RBC

• The Reticulocyte count is then used to estimate if the patient is in a regenerative or non-regenerative anemia

T/F: An increase in Reticulocyte Percentage means that the animal is in Reticulocytosis

False, RP=(Reticulocytes/RBCS), so a decrease in RBCs may make the RP appear larger, the best way to determine a regenerative vs non-regenerative anemia is to use the Reticulocyte count

What are nRBCs?

Nucleated RBCs, they are immature RBCs

T/F: We can use machines to calculate nRBC

False, they will often misclassify the nRBCs, so it is best to do it by hand

What is Rubricytosis? What is it associated with?

• An increased # of nRBCs

• Regenerative anemias

**T/F: If a Rubricytosis is present then the animal has a regenerative anemia**

False, while it is commonly seen along with regenerative anemais, it is not ALWAYS there

Inappropriate Rubricytosis (Rubricytosis associated w. non-regenerative anemias) is caused by what?

• Loss of the finely controlled release of RBCs

  • Marrow damage

  • Splenectomy

  • Splenic contraction

  • Lead toxicosis