CBC Introduction

Question 1

what cells does a CBC count?

how is a CBC obtained?

Answer 1

• requires EDTA - anticoagulated whole blood
• cell types counted
  
  • WBCs
  • RBCS
  • platelets (thrombocytes)

Question 2

how are cell counts in a CBC reported?

Answer 2

• RBCs - thousands / microliter ( out of 10³)
• RBCs millions / microliter ( out of 10⁶)
• PLT - thousands / microliter (out of 10³)

Question 3

what is the RBC indices?

what is included in the RBC indices?

Answer 3

• mean cellular volume (MCV) - average SIZE OF RBCs in sample of blood
• mean cellular hemoglobin (MHC) - the WEIGHT OF HB in the average RBCS
• mean cellular hemoglobin concentration (MCHC) - the CONCENTRATION OF HB in the average RBCs

Question 4

what does the MCV tell us?

Answer 4

RBC indices

average SIZE OF RBCs in sample of blood

• microcytic: < 80 fL ( = < 7.0 uM)
• normocytic: < 80-100 fL ( = 7.0uM - 8.5uM)
• macrocytic: > 100 fL (> 8.5 uM)

Question 5

what does the MCH tell us?

Answer 5

part of RBC indices

the WEIGHT OF HB in the average RBC

Question 6

what does the MCHC tell us?

Answer 6

the CONCENTRATION OF HB in the average RBCs

Question 7

what RBC indices would be abnormal with this scan?

Answer 7

low MHCH - low Hb concentration per average blood cell

Question 8

what are the normal absolute and relative WBC counts?

Answer 8

• normal total WBCS: 10.0 x 10³
  
  • PMNS: 65%
  • lymphocytes: 10%
  • monocytes: 25%

Question 9

what is anisocytosis?

how is it reported?

Answer 9

• variation in RBC size
• RDW-SD: standard deviation of RBC Distribution Width

Question 10

absolute vs relative anemia

Answer 10

• absolute anemia: decreased RBC mass
• relative anemia: perceived decreased RBC mass d/t increased plasma volume
  
  • pregnancy
  • excessive hydration
  • macroglobinemia

Question 11

what are common causes of microcytic hypochromic anemias?

Answer 11

• Disorders of iron metabolism
  
  • Chronic disease
  • Neoplasia
• Disorders of heme synthesis
  
  • Sideroblastic anemia
• Disorders of globin synthesis
  
  • Thalassemias

Question 12

Answer 12

polychromasia

• d/t high bone marrow recycling
  
  • in this case - hyperproliferative (hemolytic anemia)

Question 13

Answer 13

macrocytic anemia

(in this case, d/t vitamin deficiency - B12 / folate)

Question 14

Answer 14

microcytic hypochromic anemia - in this case, d/t iron deficiency