lab pro - RBC week 1

why do we have to do RBC counts, and morphology

auto-anallyzers dont detect abnormalities

what is the Ery-tic dilution factor

1:200

which square do you count for RBC counts

the super square in the center, composed of 25 squares, each with 16 tiny squares

• only use 5 of the 25; 4 corners and 1 center square

whats the volume of one square on the hemocytometer

0.004 uL

which lines count as the border for a double or triple lined square

double lined = inner line

tripple lined = middle line

what unit should your final answer of total RBC be in

 x 10^12 RBC/L

what are RBC indices helpful for

classifying anemia, provide objective measure of the size and average [Hgb]

accuracy of the RBC indices depends on what

1. total RBC count

2. PCV %

3. [Hgb]

what is hemoglobin

the functional part of the RBC

• heme portion - contains iron

• globin portion - contains amino acids

oxyhemoglobin

oxygen loaded form of Hgb

methemoglobin

stable, oxidized form of Hgb which is unable to release oxygen to the tissues

carboxyhemoglobin

binding of carbon monoxide to the Hgb

• is stable, so cannot absorb or transport oxygen

how do auto-analyzers measure [Hgb]

it lyses the cells, releasing the Hgb. the color of the sample is compared to a standard to determine [Hgb]

how do you calculate the estimated [Hgb]

amount of Hgb is close to 1/3 of the PCV, so (PCV)(0.34) = [Hgb] g/dL

mean cell volume (MCV) and the normal ranges

measures the cell size and average volume

• measure in femtoliter (fL) 1fL=10^-15 L

dogs = 60-77

feline = 39-55

equine = 34-58

is MCV is below the normal range

microcytic → RBC are smaller

is MCV is above the normal range

macrocytic → RBC larger

mean corpuscular [Hgb] (MCHC) and the normal ranges

average percent measurement of [Hgb] in each RBC

• expressed in g/dL

dog = 31-36

cats = 30-36

equine = 31-37

if MCHC below normal range

hypochromic → too light

if MCHC above normal range

hyperchromic → too dark

mean corpuscular Hgb (MCH) and normal ranges

amount or weight of Hgb of each RBC

• expressed in pictograms (pg) 1pg = 10^-12g

dogs = 14-25

cats = 13-20

equine = 13-19

RBC morphology in canines

biconcave disc shape with area of central pallor

RBC morphology in felines

round with little to no area of pallor

RBC morphology in birds, reptiles, amphibians, and fish

nucleated RBCs

RBC morphology in llamas, camelids

elongated ovals (elliptocytes)

what are the 2 methods of quantifying morphologic changes

1. scale of 1+, 2+, 3+, 4+ to indicate relative percentages of cells with changes

1+ = 5-10%

2+ = 10-25%

3+ = ~50%

4+ = >75%

2. slight, moderate, marked

slight = 10%

moderate = 25%

marked = 50%

rouleaux

• stacking of erythrocytes

• normal in horses, may be present in cats and pigs

• artifact of prolonged storage

agglutination

• RBC’s are coated in antibodies, resulting in bridges and clumps

• occurs in immune-mediated disorders (IMHA)

how to differentiate between rouleaux and agglutination

drop of saline onto the slide, rouleaux will disperse in saline

two types of anisocytosis

• variation in RBC size

• common in iron deficiency

macrocytes, microcytes

polychromasia

• RBC with blueish tint when stained with Romanowsky stain

  • presence of organelles within cytoplasm

• usually young RBC (reticulocytes) bc still have RNA

hypochromasia

• RBCs with decreased color

• could be insufficient Hgb

• very pale central region

• indicative of iron deficiency

normochromasia

normal staining :)

hyperchromasia

• darkly stained RBCs

• appears like too much Hgb

• usually microcytes or spherocytes

poikilocytes

• abnormally shaped; term not helpful in Dx

• only use term when morphologic changes cannot be more specific

schistocytes

• RBC fragments

• form from trauma of blood vessels or encounter turbulence or abnormal surfaces, so are torn or fragmented

• indicative of DIC

acanthocytes

• irregular and spiculated

• aka Spur cells

cats: indicative of hepatic lipidosis

dogs: indicative of hemangiosarcoma

echinocytes

• aka burr cells

• spikulated/crenation (shrunken)

• artifact from slow drying

dogs: indicative of renal failure, lymphosarcoma, snake bites

keratocytes

• helmet cells, blister cells, bite cells

• indicative of hemangiosarcoma, neoplasia, glomerulonephritis, hepatic disease

spherocytes

• small, dark staining RBC with reduced or no central pallor

• in dogs are large ~7mm in diameter, otherwise hard to detect

• indicative of IMHA (body attacks own RBC)

• transfusion reactions

2 kinds of leptocytes 

1. target cells

2. stomatocytes

target cells

• codocytes

• central area of Hgb in central pallor

• indicates anemia, liver disease, inherited disorders

stomatocytes

• folded cells

• slit-like pale region

• artifacts

basophilic stippling

• presence of small, dark-blue bodies

• residual RNA

• seen in immature RBC of ruminants

• indicate feline anemia, or lead poisoning

howell-jolly bodies

• basophilic nuclear remnants in young RBC in anemic response

• removed when pass through spleen

• increased numbers = spleenic disorders

Heinz-bodies

• spherical light/clear staining inclusions becasue of denatured Hgb

• oxidative injury to Hgb

• common in cats

• associated with anemia: spleen removes RBC with HB

common causes of Heinz-bodies presence

• Acetaminophen (tylonel) and Propylene glycol poisoning

• repeated doses of propofol

parasites in RBC

• Babesia → cattle, horses, dog

• Mycoplasma hemofelis → cats

  • small, coccoid, rod-shaped or ring-like and ark

  • on periphery of RBC