Erythrogram & Anemia Flashcards
What is RBC?
**RBC = Red Blood Cell count
Number of RBCs per unit of blood, M/microliter; impedance count
What is Hemoglobin (Hgb)?
Hemoglobin = the protein within RBCs that carries O2
Concentration measured in g/dL; should = 1/3 PCV%
Each heme subunit of Hgb contains an iron (Fe) molecule
What are Hematocrit (Hct) and Packed Cell Volume (PCV), and how are they different?
Both = the % of blood volume filled by RBCs
Differ in how they are measured (Hct = analyzer) (PCV = microhematocrit tube + centrifuge)
What do RBC indices measure?
The size, shape and quality of RBCs present
What are the two factors of RBC indices?
Mean Corpuscular (Cell) Volume (MCV) of circulating RBCs
Mean Corpuscular (Cell) Hgb concentration (MCHC) within circulating RBCs
MCHC measured in g/dL
MCV measured in femtolitres (fL)
Describe the separation that occurs in a microhematocrit tube after centrifuging.
The plasma (anticoagulated/free-fluid part) and the serum (PCV part) are separated to top and bottom, respectively.
Increased PCV or Hct is called what?
Erythrocytosis = Polycythemia
What can cause increased PCV?
Dehydration
Decreased PCV or Hct is called what?
Anemia
Dog: PCV ≥ 33%
Cat: PCV ≥ 26%
Patients are mildly anemia
Dog: PCV ≥ 24%
Cat: PCV ≥ 23%
Patients are moderately anemic
Dog: PCV ≤ 23%
Cat: PCV ≤ 23%
Patients are markedly anemic
What can artifactually increase or decrease PCV?
Sample storage (increase PCV%)
Hemolysis (decrease PCV %)
What can artifactually decrease Hct?
Hemolysis (decrease Hct)
What can artifactually decrease RBC?
Sample storage
RBC agglutination
What is the difference between a reticulocyte and an erythrocyte?
Two days after a reticulocyte (immature RBC) forms, it develops into an erythrocyte (mature RBC)
What is an indicator of erythroid regeneration?
Increased reticulocyte # in blood
What colors do reticulocytes versus erythrocytes routinely stain?
Reticulocytes: blue (polychromatic)
Erythrocytes: pink
What type of feline reticulocyte are the red arrows pointing to?
Punctate Reticulocytes (1-3 weeks)
What type of feline reticulocyte are the white arrows pointing to?
Aggregate Reticulocytes (1-2 days)
When does polychromasia occur on a routine stain?
Occurs when RBCs are released too early from the bone marrow (a.k.a. immature//reticulocytes)
What is an appropriate response to anemia?
Regenerative Anemia: increased polychromatophilic RBCs in peripheral blood (reticulocytosis)
What species are reticulocytes not released in?
Equines
What is the cutoff range for regenerative anemia in dogs/cats?
Dog = greater than 80,000 per microliter
Cat = greater than 60,000 per microliter
Which type of feline reticulocyte is indicative of ACTIVE RBC regeneration?
Aggregate
What are metarubricytes?
Nucleated RBCs (nRBCs) / the stage of RBCs that directly precedes the reticulocyte stage
True or False: increased nRBC numbers (metarubricytosis) are always indicative of regenerative anemia
False
increased nRBC numbers may accompany regeneration
When is metarubricytosis considered appropriate?
When it occurs concurrently with regenerative anemia.
When is metarubricytosis considered inappropriate?
When it occurs in the absence of reticulocytosis (regenerative anemia)
What types of diseases or situations can cause inappropriate metarubricytosis?
- damage to the membranes that separate the hematopoietic spaces from the marrow spaces (due to heat stroke, heavy metal toxicity, hypoxemic bone marrow injury [severe anemia], infection)
- recent fracture or orthropedic sx
- splenic disease or injury (spleen clears nRBCs)
- errythroid leukemia (cats)
Why won’t you typially see nRBC value on a CBC?
Because the normal, healthy nRBC range is very low; will only appear if value is high
What is macrocytic anemia and how does it appear on a CBC?
Enlarged RBCs
Elevated MCV (due to agglutination)
What is microcytic anemia and how does it appear on a CBC?
Shrunken RBCs
Decreased MCV, MCHC
Decreased MCHC = hyprochromic
What artifacts can cause microcytic anemia?
-
Short draws (low blood volume collected in sample)
–> excess EDTA to blood ratio - Hyponatremia (low serum Na levels)
Hyponatremia most offen occurs when the body retains water as an attempt to preserve electrolytes, especially after v+ or d+ episodes.
What artifacts can cause macrocytic anemia?
- RBC agglutination
- Sample storage
- Hypernatremia
- Hyperglycemia
Hypernatremia is caused by inadequate water intake (can be life-threatening if px is markedly hypernatremic)
Hyperglycemia = elevated BG
What is hyperchromic anemia and how does it appear on a CBC?
Hyperchromic Anemia is NOT real, and is a result of technical artifact!
Elevated Hgb levels
Elevated MCHC
Elevated MCHC indicates an excess amount of hemoglobin, but RBCs can’t have ‘excess’ hemoglobin, so it usually implies free hemoglobin in plasma.
What is hypochromic anemia and how does it appear on a CBC?
Decreased Hgb levels
Decreased MCHC
What is the #1 pathological cause of microcytic anemia?
Iron deficiency
Causes insufficient Hgb concentration, which causes an extra rubricyte division cycle to occur, producing shrunken RBCs
What are some examples of technical artifacts that result in hyperchromic anemia?
- short draws
- hemolysis
- lipemia
This is a result of a traumatic blood draw (with rupture of RBCs and release of hemoglobin) or intravascular hemolysis (due to a problem with the RBCs, e.g. oxidative injury, immune mediated damage, RBC infectious agents)
What are some pathologic causes of hypochromic anemia?
- Iron deficiency
- Reticulocytosis
- Liver disease
What are key clues that support macrocytic, hypochromic anemia?
Reticulocytosis
Regenerative anemias can also be macrocytic, normochromic or normocytic, hypochromic – so it is the reticulocyte count that is most important!
What are key clues that support microcytic, hypochromic anemia?
Iron deficiency
Why is hypoplasia (atrophy) considered non-regenerative anemia?
Because there is a lack of cells in the bone marrow that can produce/develop into new RBCs
Erythroid hypoplasia – bone marrow is not responding to a peripheral need for RBCs
Why are hemorrhages and hemolysis considered regenerative anemia?
Blood loss signifies a need for more RBCs
Erythroid hyperplasia – appropriate bone marrow response to peripheral need for RBCs (e.g. blood loss resulting in a decrease in peripheral tissue oxygen tension)
What are signs of anemia in an animal?
Pale mucous membranes, tachycardia, exercise intolerance
