Clinical Pathology Exam 1

Reference intervals & data interpretation,

What are biological criteria used for defining a population?

• species

• age

• sex

• breed

what are environmental criteria used for defining a population?

• climate

• altitude

• diet

• season

Gaussian distribution is

symmetrical

non-gaussian distribution is

asymmetrical

what distribution pattern is shown in this image?

Gaussian

what distribution pattern is shown in this image?

non-gaussian

in Gaussian distribution, how is the reference interval calculated?

mean ± 2 SD

the reference interval only covers ___% of the population

95

what is the proportion of individuals that fall outside of the RI despite being “healthy”?

1:20

what number of individuals creates a population for the sake of RI?

120

T/F: every value outside of the RI is “abnormal” and should be treated as such

False

CBC includes the evaluation of

• red blood cells

• white blood cells

• platelets

Direct RBC measurands include

• RBC count

• packed cell volume (PCV)

• hemoglobin concentration

• mean cell volume (MCV)

• reticulocyte count

direct WBC measurands include

• WBC/ total nucleated cell count

• differential cell count

direct platelet measurands include

• PLT count

• mean platelet volume (MPV)

Red cell morphology, reticulocyte %, differential white/ nucleated cell % and platelet morphology are considered

microscopic procedures

what are RBC calculations included in CBC?

• hematocrit

• mean cellular hemoglobin concentration

• red cell distribution width (RDW)

• absolute reticulocyte count

what is the WBC calculation included in CBC?

absolute differential WBC count

describe impedance

• electronic cell counting

  • cells are suspended in an electrolyte medium that conducts electricity

  • cells are relatively poor conductors of electricity

  • deflection in current are proportional to the size of the cell, allowing the counting and measuring of cells

what is the formula for red cell distribution width (RDW)?

RDW = SD/MCV

define anisocytosis

variation in the size of RBC

describe flow cytometry

• light scatter measurement

  • cells pass through a flow cell that is intersected by a focused laser beam

  • physical properties of the cells scatter light to different degrees and different angles relative to the light source

  • number of scatter events are counted to derive the cell count

forward scatter is proportional to

size of the cell

side scatter is correlated to

cellular complexity

what contributes to a cells complexity?

• the presence of granules

• hemoglobin content

define PCV

% of erythrocytes volume over whole blood volume

what is 1?

normal PCV

what is 2?

severely hemolyzed

what is 3?

mildly hemolyzed

what is 4?

Dog or cat: icterus

Horse or ruminant: normal

refraction is proportionate to the _______ in a sample

solute concentration

what is the best layer on a blood smear to analyze morphology and count cells?

monolayer

what is the stain used to analyze and count reticulocytes?

new methylene blue (NMB)

define hematopoiesis

proliferation and progressive differentiation of hematopoietic stem cells into mature blood cells

define erythropoiesis

maturation and differentiation of RBC

define leukopoiesis

maturation and differentiation of WBC

define thrombopoiesis

maturation and differentiation of platelets

what is the main function of erythrocytes?

carry oxygen to tissues

what is the typical shape of erythrocytes in mammals?

• no nuclei and no organelles

• circular, flattened bi-concave

• diameter: 4-8 um

what are the 2 important characteristics of erythrocytes?

• discoid shape

• plasticity

describe discoid shape

• larger surface area to volume ratio

• minimal diffusion distance

• greater tolerance to osmotic swelling

describe plasticity

• tolerance for shape change

• cytoskeleton

Total RBC mass is regulated by

cellular oxygen levels

cellular hypoxia results in

increased secretion of EPO

what is the order of cells in erythropoiesis?

• rubriblast

• prorubricyte

• basophilic rubricyte

• polychromatophilic rubricyte

• metarubricyte

• reticulocyte

• erythrocyte

what are the nutrients that are required for RBC production?

• iron

• vitamins B6, B9, B12

• copper

• cobalt

what organ is responsible for producing EPO?

kidney

where is the best area to examine RBC and WBC morphology on a blood smear?

monolayer

describe marcocytosis

• larger RBCs

• typically less mature cells

• polychromatophils

describe microcytosis

• smaller cells

• iron deficiency

what is the arrow pointing to in this image?

shows an abrupt change from color to pale

• normal artifact where the hemoglobin is concentrated on the edge

what is the stain used to count reticulocytes?

new methylene blue

when reticulocytes are stained with Wrights stain, they appear as

polychromatic RBC

describe echinocytes

• numerous short spicules

• crenation

• in vivo formation electrolyte imbalances

• rattlesnake envenomation

• non-specific diseases (ex. kidney disease)

what type of cell is shown in this image?

echinocytes

describe acanthocytes

• few unevenly distributed projection due to changes in lipid concentrations in RBC membrane

• humans with liver disease

• cats with hepatic lipidosis

• dogs with hemangiosarcoma

what type of cell is shown in this image?

acanthocytes

describe schistocytes

• erythrocyte fragments

• intravascular trauma

  • DIC, vascular tumors

• iron deficiency

• anemia

what is the arrow pointing to in this image? arrow-head?

arrow: acanthocyte

arrow head: schistocyte

describe keratocyte

one or two spicules, often formed by breaking open of “blisters”

what is the arrow pointing to in this image?

keratocytes

describe spherocytes

• erythrocytes that appear small and lack central pallor

• volume is normal

• presence suggests IMHA

what is the red arrow pointing to in this image?

spherocyte

what is the arrow pointing to in this image? arrow head?

arrow: imperfect spheres

arrow head: spherocytes

briefly describe how spherocytes are formed?

macrophages attack part of the RBC that is marked with the antibody

describe heinz bodies

oxidatively denatured hemoglobin

what causes heinz body formation?

• acetaminophen

• propylene glycol

• illnesses: lymphoma, hyperthyroidism, diabetes

• onions

• cephalosporins

• zinc toxicosis

what causes heinz body formation in horses?

• phenothiazine

• wilted red maple leaves

what causes heinz body formation in cattle?

• kale

• onions

what causes heinz body formation in sheep?

copper toxicosis

describe eccentrocytes

• shifting of hemoglobin to one side of cell, resulting in clear zone outlined by membrane

• caused by oxidative damage such as may be seen with ingestion of onions in dogs

• often seen in conjunction with heinz body formation

what is shown in this image?

eccentrocytes

describe leptocytes and codocytes

• “target cells”

• “bowl” shaped cells

• folded cells

• of little diagnostic significance

describe stomatocytes

• mouth-like clear area in the center of the RBC

• a few are usually present and are insignificant

• hereditary stomatocytosis reported in

  • alaskan malamutes

  • miniature schnauzers

  • drentse partrijshond