244. Intro to CBC Flashcards
Define the following CBC indices:
HCT MCV MCH MCHC RDW
What is anisocytosis? poikilocytosis?
HCT: % RBC volume in whole blood sample
MCV: mean corpuscular volume; average size of RBC
MCH: mean corpuscular hemoglobin; Hb content in RBC
MCHC: mean corpuscular hemoglobin concentration; Hb concentration in RBC
RDW: degree of size variation in RBC
MCH and MCHC indicate if hypochromic, normochromic, hyperchromic
Anisocytosis: abnormal size
Poikilocytosis: abnormal shape
What would cause Hb to be falsely abnormal? Higher or lower?
Hb measured by light absorbance in blood sample
Increase sample turbidity = falsely high Hb level
- hyperlipidemia
- hyperbilirubinemia
- abnormal protein
- marked leukocytosis
What would cause MCV to be falsely abnormal? higher or lower?
Falsely high MCV
- agglutination (RBCs form clumps)
- significantly increased reticulocytes (young RBCs)
- osmotic abnormalities (hyperglycemia, hypernatremia - causes RBCs to swell in diluting solution)
What would cause platelet counts to be falsely abnormal? higher or lower?
Falsely low platelet count
- clotted blood sample (platelets trapped in blod clot)
- platelet clumping
- significant number giant platelets (not counted as single platelets due to larger size for machine to register)
What does the peripheral blood smear for Fe Deficiency look like?
Microcytic hypochromic RBCs
What do target cells indicate?
- CHRONIC LIVER DISEASE
- lipid disorder
- hemoglobinopathy (thalassemia, hemoglobin C)
What do Burr cells indicate?
Symmetric short, sharp projections
- Acute renal failure (KIDNEY DISEASE)
- Iron deficiency
- Lab artifact
What do teardrop cells indicate?
- Bone marrow fibrosis (MYELOFIBROSIS)
- Iron deficiency
What do spherocytes indicate?
Dark RBC with no central pallor
- hereditary spherocytosis (intrinsic defect in membrane)
- immune-mediated hemolytic anemia (autoimmune IgG Ab’s cause macrophages to fragment RBCs, remainder forms spherocytes)
What do schistocytes indicate?
Irregulary shaped RBC fragments
Due to microclots in circulation high in fibrin meshwork - pumping RBCs thru fibrin network causes fragmentation of RBCs
Microangiopathic hemolytic anemia (MAHA)
- DIC (disseminated intravascular coagulation)
- HUS (hemolytic uremic syndrome)
- TTP (thrombotic thrombocytopenic purpura)
- artificial cardiac valves
What are the components of blood and how much of total blood do they take up?
- RBC (45%)
- WBC & Platelet (~0% - thin buffy coat)
- Plasma (55%) - water, protein, glucose, electrolytes, clotting factors, hormones, AAs, vitamins
What is the difference between CBC and CBC with differential?
CBC: measurement of total WBC count and specific RBC parameters by automated hematology analyzers
Differential: % of each subtype of WBC over total WBC count; absolute count of each subtype of WBC per microliter
What would cause RBC count to be falsely abnormal? higher or lower?
Falsely high RBC count:
- marked leukocytosis (counted as RBC, usually negligible in normal pt)
- giant platelets
Falsely low RBC count:
- RBC aggregation (cold agglutinin)
- microcytosis (too small to be counted)
- fragmented RBC
What would cause HCT to be falsely abnormal? higher or lower?
What is the “Rule of Three?”
Falsely high HCT
- marked leukocytosis
- hyperglycemia (causes RBC swelling in diluting solution)
Falsely low HCT
- red cell agglutination
- microcytosis
RULE OF THREE
RBC count x3 = HGB
HGB x3 = HCT
What is agglutination and what conditions does it suggest?
RBCs form clumps due to antibodies (usually IgM) against RBCs
- cold agglutinins
- some lymphomas with monoclonal IgM
- infection (mycoplasma pneumoniae, EBV, HCV)
