Complete Blood Count Flashcards
(33 cards)
What is the definition of anemia?
Abnormally low blood hemoglobin concentration in whole blood samples
Is anemia a disease or is it a sign of disease?
Anemia is NOT a disease, it is a sign of disease
What are the two primary causes of anemia?
- Premature destruction of RBCs and/or acute blood loss
- Insufficient production of RBCs
What is erythropoiesis (describe the process in 3 steps)? Where does this occur?
Erythropoiesis is the production of RBCs in the bone marrow
- Demand of RBCs triggers signal that leads to stem cell differentiation into blast cells - a single BFU-E can divide into a colony of 1000+ RBCs
- As erythropoiesis progresses, a series of blast cells (BFE-U) will form that decrease in size with each division
- Before becoming a mature RBC (erythrocyte), reticulocytes are formed
What is a reticulocyte and what are 4 characteristics of a reticulocyte? What percentage of the RBC population do they make up?
Reticulocyte: immature RBC that make up 0.5-1.5% of the population of circulating RBCs
- 20% larger than immature RBC
- No nucleus
- Contain some ribosomes and mRNA
- Only contain 80% of Hb found in mature RBCs
What is the general lifespan of one RBC and where are they destroyed (3)?
RBCs live for 120 days, then they are destroyed in the spleen, liver or bone marrow
How long does it take for a reticulocyte to mature? How is this different in a person with anemia?
Reticulocytes take 72 hours to mature, with 48 hours in bone marrow and 24 hours in circulation
- With anemia, reticulocytes are needed for their HB and instead spend 24 hours in bone marrow and 48 hours in circulation
For pro-normoblasts, reticulocytes and mature RBCs, are the following yes or no:
- Nuclear DNA present?
- Cytoplasmic RNA present?
- Present in bone marrow?
- Present in circulation?
Pro-normoblasts:
- Nuclear DNA present: Yes
- Cytoplasmic RNA present: Yes
- Present in bone marrow: Yes
- Present in circulation: No
Reticulocytes:
- Nuclear DNA present: No
- Cytoplasmic RNA present: Yes
- Present in bone marrow: Yes
- Present in circulation: Yes
Mature RBCs:
- Nuclear DNA present: No
- Cytoplasmic RNA present: No
- Present in bone marrow: No
- Present in circulation: Yes
What is erythropoietin, and where is it produced? What is the signal for synthesis?
Erythropoietin (EPO): hormone secreted by the kidneys that stimulates the process of RBC production
- EPO receptors are found in bone marrow and synthesis signal is renal hypoxia
In patients with chronic kidney failure, how is EPO administered? What is this used to prevent (clinically)?
Recombinant EPO must be injected regularly to prevent severe anemia
- At least one healthy kidney is needed to produce EPO naturally
What are the five ways in which EPO works to stimulate RBC production?
- Increased number of CFU-E cells via inhibition of CFU-E apoptosis
- Increased Hb synthesis
- Increased iron absorption
- Increased rate of erythroid differentiation
- Stimulated production/premature release of reticulocytes from bone marrow
What is found to be elevated in many types of anemia, and what is it? (hint: think Hb lecture)
Hb allosteric inhibitor, 2,3-BPG
- It helps to carry more O2 to the tissues by making it harder for oxygen to bind Hb
What are the nutrient requirements for:
- Adequate cell division? (2)
- Adequate Hb synthesis? (4)
What is the consequence if any of these nutrients are lacking?
Adequate cell division:
- Folic acid
- Vitamin B12
Adequate Hb synthesis:
- Dietary protein (AAs)
- Iron
- Copper
- Vitamin B6
If any of the above nutrients are missing, there will be reduced erythropoiesis leading to anemia
What is RBC in terms of laboratory evaluation?
Concentration of RBCs per a give volume of whole blood
What is Hb in terms of laboratory evaluation?
Concentration of hemoglobin in a given volume of whole blood
What is HCT in terms of laboratory evaluation?
Hematocrit: volume percentage of whole blood occupied by RBCs
What is Reticulocyte Count? What are the two types and what does each measure?
Reticulocyte count: reflects levels of erythropoiesis in bone marrow
- Observed reticulocyte count (OR): represents number of reticulocytes as percentage of RBCs (typically 0.5-1.5%)
- Corrected reticulocyte count (CR): corrected to prevent an overestimation in anemic individual
What is the equation for Observed Reticulocyte Count (OR)?
OR = (# of reticulocytes / # of RBCs) x 100
What is the equation for Corrected Reticulocyte Count (CR)?
CR = (Patient’s HCT / mean normal HCT) x OR value
What are the corpuscular indices used to determine? What are the three types of corpuscular measurements in terms of laboratory evaluation?
Determine the morphological classification of anemia (color, size)
- Mean Corpuscular Volume (MCV)
- Mean Corpuscular Hb (MCH)
- Mean Corpuscular Hb Concentration (MCHC)
What does the Mean Corpuscular Volume (MCV) measure? What are the three result ranges and what does each indicate?
Mean Corpuscular Value (MCV) measures the average volume of circulating RBCs
- Microcytic: <80 (smaller than average size)
- Normocytic: 80-100 (average size)
- Macrocytic: >100 (larger than average size)
What is the equation for MCV?
MCV = HCT / RBC x 10
What does the Mean Corpuscular Hemoglobin (MCH) measure? What is the average result range?
Mean Corpuscular Hb (MCH) measures the quantity of Hb in the average circulating RBC
- Average: 26-32 pg
What is the equation for MCH?
MCH = Hb / RBC x 10
