CBC

• Complete Blood Count (CBC) is used to determine general health status and screen for, diagnose, or monitor diseases and conditions that affect blood cells such as anemia, infection, inflammation, bleeding disorders, or cancer
• Sample required for CBC is a blood sample drawn from a vein in the arm or a Fingerstick or heel-stick for newborns
• A CBC includes Red blood cell (RBC) tests, White blood cell (WBC) tests, and Platelet tests
• Red blood cell (RBC) tests include:

  • RBC count: actual number of red blood cells in the blood sample
  • Hemoglobin: measures the total amount of oxygen-carrying protein in the blood
  • Hematocrit: measures the percentage of total blood volume consisting of red blood cells
  • Red blood cell indices: provide information on the physical features of RBCs such as MCV (average size of blood cells), MCH (amount of hemoglobin), MCHC (concentration of hemoglobin), and RDW (variation in size of blood cells)
• Hemoglobin is composed of globin and heme, and the normal range is 13.5 to 17.5 grams per deciliter for men and 12.0 to 15.5 grams per deciliter for women
• Abnormal RBC morphology includes:

  • Anisocytosis: red blood cells of varying sizes
  • Poikilocytosis: red blood cells of varying shapes
  • Red blood cell inclusions like Howell-Jolly bodies, Heinz bodies, Basophilic stippling, Pappenheimer bodies, and Cabot Ring
• White blood cell (WBC) tests include:

  • WBC count: total number of white blood cells
  • WBC differential: identifies and counts the number of different types of white blood cells present
• • Döhle bodies: irregular grayish or bluish inclusions in the peripheral cytoplasm of neutrophils, often seen in association with toxic granules and vacuoles, may be present in association with infections, burns, trauma, or exposure to cytotoxic agents (i.e., chemotherapy), may also be seen after cytokine stimulation (e.g., G-CSF) or during a normal pregnancy
  • Auer rods: unique, pink or red rod-shaped inclusions seen in very immature myeloid cells ("blasts") or rarely more mature neutrophils in people with acute myeloid leukemia or high-grade myelodysplastic syndrome
• Anomalies of neutrophils:

  • Toxic granulation: large dark blue granules in the cytoplasm, associated with severe infection, burns, trauma, and G-CSF colony stimulating factor therapy
  • Vacuolization: vacuoles appear as holes in the cytoplasm and are frequently found in association with toxic granulation but can also be a degenerative feature seen when the blood is stored for a prolonged period of time before preparing the blood smear
• • Bands – increased numbers: slightly immature neutrophils are normal in the circulation in small numbers, but if there is a percentage increase of them, there is said to be a "left shift," may happen when an acute infection stimulates increased neutrophil production, causing the bone marrow to prematurely release some WBCs before they have matured to the neutrophil stage
• Anomalies of lymphocytes:

  • Reactive lymphocyte (atypical lymphocyte, activated lymphocyte): large lymphocytes that contain a greater amount of cytoplasm and can vary in size and shape, often found in viral illnesses such as infectious mononucleosis
  • Hairy cells: lymphocytes with tiny projections that make them appear hairy under the microscope, found in hairy cell leukemia
• • Mature hematopoietic cells develop within a few days after bone marrow transplantation and even more rapidly following peripheral stem cell transplantation
• Bone marrow cell morphology:

  • A normal bone marrow shows a mixture of both developing blood cells and mature blood cells ready to be released into the blood stream
  • The most immature cells are called blasts and should only be seen in very small numbers
  • Normal bone marrow contains the precursors of erythrocytes, granulocytes, platelets, stromal cells, tissue mast cells, B lymphocytes, and occasional osteoblasts
  • Reticulum cells are sparse in pure bone marrow fluid but are more plentiful in the smear from a bone marrow fragment
• Bone Marrow Aspiration:

  • Determines the M/E ratio (myeloid/erythroid ratio) comparing the number of myeloid cells (WBC precursors) to erythroid cells (RBC precursors)
  • Differential determines whether cells in each lineage (WBC, RBC, platelet-producing cells) show orderly and complete maturation and whether the cells are present in normal proportion to one another
  • Presence of any abnormal cells, such as leukemic or tumor cells
• Bone Marrow Biopsy:

  • Evaluates cellularity comparing the volume of cells to the volume of other components of the bone marrow, such as fat, and whether cellularity is normal for age, increased, or decreased
  • Determines if different cell lineages (myeloid, erythroid, and megakaryocytic) are present in adequate numbers
  • Checks for abnormal infiltrates in the marrow (cancer, infection) and any changes to the bone marrow stroma (fibrosis) or bone itself (osteoporosis)
• Erythrocyte sedimentation rate (ESR):

  • Indirectly measures the degree of inflammation present in the body
  • Measures the rate of fall (sedimentation) of erythrocytes (red blood cells) in a sample of blood placed into a tall, thin, vertical tube
  • Results are reported as the millimeters of clear fluid (plasma) present at the top portion of the tube after one hour
  • Normal ESR test results:
  • Women under age 50: 0-20 mm/hr
  • Men under age 50: 0-15 mm/hr
  • Women over age 50: 0-30 mm/hr
• High ESR may be related to an inflammatory condition such as:

  • Infection
  • Rheumatoid arthritis
  • Rheumatic fever
  • Vascular disease
  • Inflammatory bowel disease
  • Heart disease
  • Kidney disease
  • Certain cancers
•  Howell-Jolly bodies

  • remnants of RBC nuclei that are normally removed by the spleen caused by hyposplenism - sickle cell anemia, liver cirrhosis, rheumatoid arteritis, coeliac disease, inflammatory bowel disease.
• Heinz bodies

  • clumps of damaged hemoglobin attached to your red blood cells. 
• Basophilic stippling

  irregular basophilic granules, made up of RNA fragments, common in lead poisoning.
• Pappenheimer Bodies

  • small debris containing iron that can be found in red blood cells. This debris is normally eliminated by the spleen. Pappenheimer bodies are found in patients with no spleen.
• Cabot Ring

  basophilic loop seen within red blood cells, made up of mitotic spindle remnants.  

  Causes : Megaloblastic anaemia - B12 / folate deficiency, drugs, myelodysplastic syndrome
• Nuclear changes leukocytosis with leukocyte

  • A “left shift” is a phrase used to note that there are young/immature white blood cells present
  • “Right shift” is a phrase used to note the reduced count or lack of young neutrophils in blood smear, associated with the presence of giant neutrophils.
• Neutrophilia:

  • Increase of neutrophils more than 70% in the hemogram
  • Noted in acute infectious diseases, purulent inflammation, myocardial infarction, bites of poisonous insects after acute blood loss, alimentary and emotional physiological leucocytosis
• Lymphocytosis:

  • Increase in lymphocyte content of over 45% in the hemogram
  • Developed in infectious diseases (typhoid, mumps, whooping cough, malaria, brucellosis, infectious mononucleosis, tuberculosis, syphilis)
  • Associated with the formation of anti-infective immunity, malnutrition, asthma, and some endocrine disorders (syndrome: myxedema, acromegaly)
• Monocytosis:

  • Increase of monocytes over 9% in the hemogram
  • Revealed by persistent bacterial and viral infections (tuberculosis, infectious mononucleosis, measles, rubella), inflammatory diseases (ulcerative colitis, sprue, collagen), hemoblastosis, breast cancer, ovarian cancer, after splenectomy
• Eosinophilia:

  • Increase of eosinophils in excess of 5% in the hemogram
  • Associated with reaction to foreign proteins, histamine, infestation by parasites, and anti-toxic, anti-histamine function of eosinophils
• Basophilia:

  • More than 1% basophils in the hemogram
  • Encountered in anaphylactic and reaginic allergic reactions, vaccination, hemolytic anemia, hemophilia, endocrinopathy (diabetes, myxedema), chronic myeloid leukemia
• Neutropenia:

  • Severe, overwhelming infection (sepsis), autoimmune disorders, dietary deficiencies, reaction to drugs, immunodeficiency, myelodysplasia, bone marrow damage (e.g., chemotherapy, radiation therapy), cancer that spreads to the bone marrow, congenital neutropenia
• Lymphocytopenia:

  • Autoimmune disorders (e.g., lupus, rheumatoid arthritis), infections (e.g., HIV, viral hepatitis, typhoid fever, influenza, Covid-19), bone marrow damage (e.g., chemotherapy, radiation therapy), corticosteroids
• Monocytopenia:

  • Usually, one low count is not medically significant
  • Repeated low counts can indicate bone marrow damage or failure, hairy cell leukemia, aplastic anemia
• Eosinopenia:

  • Can be observed on the background of stress, glucocorticoid therapy, acute phase response, myelotoxic agranulocytosis, malignant tumors with disease, Cushing’s syndrome
• Basopenia:

  • Low numbers are normally not medically significant