MMSC 423 Exam 3 (rough)

Electrical impedance

technique based on the measurement of the electrical properties of cells as they pass through an electric field

what principle does the Beckman-Coulter analyzer utilize?

electrical impedance

what does Beckman-Coulter measure measure?

WBC count and differential

RBC and PLT count

hemoglobin

MCV (from RBC histogram)

Hgb measurment

the concentration of hemoglobin in g/dL of blood

measured using spectrophotometry

Hct measurment

the volume percentage of RBCs in whole blood

determined by measuring packed cell volume (PCV) using centrifugation or electrical impedance

RBC measurement

the number of RBC per uL or mm³ of blood

typically measured using electrical impedance or flow cytometry

WBC measurement

number of WBC per uL or mm³ of blood

measured using electrical impedance, flow cytometry, or optical detection methods

WBC count reference values

• Lymphocytes: 35-90 fL

• Mononuclears: 90-160 fL

• Granulocytes: 160-450 fL

PLT measurment

number of platelets per uL or mm³ of blood

determine using electrical impedance or optical detection methods

MCV measurement

measures mean volume of RBCs

MCV= (Htc% x 10) / RBC count

MCV normal range

80-100 fL

MCH measurement

measures average amount of Hgb in each RBC

MCH= Hgb x 10/RBC count

MCH normal range

26-32 pg

MCHC measurement

measures mean concentration of Hgb in each RBC

MCHC: Hgb x 100/Hct

MCHC normal range

32-36%

RDW

provides info about the variation in size of RBCs

RBC histogram width measurement (in %)

MCV and Normocytic Anemia

MCV within normal range (80-100 fL)

can be seen in actute blood loss, kidney diseases, anemia of chronic disease

MCV and Microlytic anemia

MCV is less than 80 fL

can be seen in iron deficiency and anemia of chronic disease

MCV and Macrocytic anemia

MCV is higher than 100 fL

can be seen in vitamin B12 deficiency

MCH and Microlytic anemia

low MCH values

can be caused by iron deficiency

small RBCs

MCH and Normocytic anemia

wide range of MCH values

can be caused by certain kidney diseases, acute blood loss, anemia of chronic disease

normal sized RBCs

MCH and Macrocytic anemia

elevated MCH values

can be caused by vitamin B12 deficiency, some. meds, some bone marrow disorders

large RBCs

MCHC and Microcytic Hypochromic anemia

associated with low MCHC values and decreased hemoglobin content

most common cause is iron deficiency

small RBCs and decreased Hgb

MCHC and Normocytic Normochromic anemia

MCHC values within normal range

can be caused by acute blood loss, kidney disease, anemia of chronic disease

normal sized RBCs and normal Hgb

MCHC and Macrocytic Normochromic anemia

MCHC values within normal range

caused by vitamin B12 deficiency

large RBCs and normal Hgb

MCV and MCHC values:

normocytic / normochromic

normal MCV

normal MCHC

MCV and MCHC values:

microcytic / hypochromic

decreased MCV

decreased MCHC

MCV and MCHC values:

macrocytic / normochromic

increased MCV

normal MCHC

increased MCH can lead to what type of anemia?

immune hemolytic anemia

3-part WBC differential

broad categorization based on staining properties and morphology

neutrophils, monocytes, lymphocytes

5-part WBC differential

provides relative percentages of five cell types —> detailed assessment of immune system

segmented neutrophils, eosinophils, basophils, lymphocytes, monocytes

The 4 specimen interference consists of:

cold agglutinin

lipemia

hemolysis

blood clots

lipemic specimen

refers to a blood sample that appears cloudy or milky due to an excess of lipids in the plasma

occurs because of patient’s diet, medical conditions, or improper sample handling

lipemic specimen interference with Hb and Hct

lipemia can falsely increase the measured values of Hb and Hct

the lipids in plasma causes light scattering —> overestimation of RBC concentration

lipemic specimen interference and WBC count

cloudiness of plasma causes cell counters to inaccurately detect and differentiate WBC from lipids

can result in falsely low WBC count or errorneous identification of cell types

lipemic specimen interference and RBC count/indices

presence of lipids can lead to increased light scatter and alter the optical properties of the sample

can affect MCV, MCH, and MCHC

lipemic specimen interference PLT count

lipid particles in plasma can resemble platelets

leads to false-pos or incorrect identification by automated counters

can result in overestimation or underestimation of true platelet count

what is increased in a lipid specimen for CBC?

Hgb

MHC

turbidity

how to handle a lipemic specimen

1. centrifuge specimen

2. remove plasma and replace with equal amount 0.85% saline

3. re-suspend contents and reanalyze on instrument

Retic count

determines general number of RBC in retic

(# of retics/1000 RBCs) x 100

normal value for retic count?

0.5-1.5%

Absolute reticulocyte count calculation

calculates the number of retics in 1L of blood

ARC = (retic % x RBC count) / 100

normal absolute retic count range

20-115 × 10⁹ / L

Absolute lymphocyte calculation

percent of particular WBC in differential

WBC count x (% lymphocytes/100)

reticulocyte production index calculation

(retic count % x Hct% / 45%) / maturation time

corrected reticulocyte count calculation

compares patient Hct with normal Hct values

(pt retic% x pt hct %) / 45

corrected reticulocyte count normal value

0.5-2.5%

relative vs absolute count

relative count refers to the percent of a particular WBC from the WBC differential

absolute count is determined by multiplying the relative count (%) by the total WBC and then dividing by 100

hematocrit (Hct)

a measure of the volume percentage of RBCs in whole blood. It is often correlated with Hb levels

calculation to predict Hct from Hgb

Hct= 3 x Hgb

MCV-based Hct estimation

Hct (%): (Hb in g/dL / MCV in fL) x K

If Hb is in g/dL and MCV in fL, K=3

If Hb is in g/L and MCV is in um³ , K=0.01

presence of nRBCs on a WBC histogram

the presence of nRBCs (nucleated RBCs) can be recognized by observing the shifted peaks, abnormal peal position, and higher cell counts

shifted peaks

typically nRBCs are larger in size compared to mature WBCs, so presence would cause a noticeable “peak” on higher side of WBC histogram

abnormal peal position

nRBCs should not be present in the region where mature WBCs are counted

might appear in the region where smaller cells are normally counted

higher cell counts

presence of nRBCs can lead to an overall increase in WBC count

nRBCs are often counted as part of the WBC population

hematopoiesis

the development of blood cells

stages of hematopoiesis

weeks 2-8: embryonic hematopoiesis

weeks 9-30: fetal hematopoiesis

week 30-birth: bone marrow dominance

after birth: postnatal hematopoiesis

embryonic hematopoiesis

occurs from weeks 2-8 of embryonic development

blood cell development takes place in the yolk sac

yolk sac produces primitive erythroblasts, the earliest precursor cells for RBCs

fetal hematopoiesis

occurs from week 9-30 of fetal development

primarily occurs in the liver and spleen

at later weeks, hematopoiesis occurs in BM

spleen produces lymphocytes, monocytes, and granulocytes

mesoblastic phase

starts ~19 days gestation

RBCs made in the yolk sac

hepatic phase

occurs between weeks 5-7 of gestation

RBCs made in the liver, some in the spleen

medullary (myeloid) phase

occurs from ~25 weeks gestation

RBCs made primarily in the bone marrow

antonym for fetal erythropoiesis

young liver synthesizes blood

yolk sac, liver, spleen, BM

bone marrow dominance

occurs from weeks 30-birth of fetal development

hematopoiesis transitions to the bone marrow and it becomes responsible for the production of RBCs, WBCs, and PLTs

hematopoietic stem cells in bone marrow differentiate into various blood cell lineages

post-natal Hematopoiesis

occurs after birth

hematopoiesis continues to occur in the bone marrow throughout life

stem cell differentiation gives rise to all blood cell types including RBCs, leukocytes, and PLTs

the bone marrow is the primary site of:

erythropoiesis, myelopoiesis, and lymphopoiesis

erythropoiesis

red blood cell production

where can active bone marrow be found in adults?

axial and appendicular skeleton

most common sites for bone marrow aspiration

posterior iliac crest

sternum

anterior iliac crest

functions of the spleen

immune function

blood filtration and storage

hematopoiesis

iron metabolism

removal of abnormal cells and particles

spleen function—blood filtration and storage

spleen removes abnormal or damaged blood cells from circulation

helps break down and recycle hemoglobin from these cells

also stores a reserve of healthy RBCs and PLTs which is released into circulation when needed

spleen function—hematopoiesis

spleen serves as a temporary site for hematopoiesis until the bone marrow takes over

spleen function—iron metabolism

spleen recycles iron from abnormal/old RBCs and releases it back into circulation for erythropoiesis in bone marrow

spleen function—removal of abnormal cells and particles

spleen removes old/non-functional RBCs from circulation

asplenia

anatomical absence of or non-functional spleen

pathogens are harder to fight

culling

phagocytosis and degradation of RBCs

pitting

removal of RBC inclusion and damaged cells by macrophages

what causes howell-jolly bodies?

severe anemia or the absence of spleen

RBCs do not complete nuclear extrusion during development in the bone marrow

what are the two primary sites of lymphopoiesis?

bone marrow and thymus

what are the three secondary lymph organs?

spleen, lymph nodes, MALT

cells of the thymus

lymphoid

macrophages

dendritic cells

reticular cells

functions of the thymus

cytokines

immune defenses

site of T cell differentiation

(IL-7 and FLT 3 Ligand)

thymus and T cell production

cortex facilitates T cell maturation

medulla facilitates T cell maturation (positive and negative selection)

cells of bone marrow

hematopoietic stem cells

mesenchymal cells

osteocytes

function of bone marrow

erythropoiesis

leukopoiesis

thrombopoiesis

Bone marrow and B cell production

bone marrow stores hematopoietic stem cells, the precursor to all blood cells

HSCs differentiate into B lymphoid progenitors and then pro-B cells

bone marrow contains cytokines and extracellular matrix which facilitates B cell proliferation

what type of cells line MALT areas and are a source for cytokines and lymphopoiesis?

epithelial cells

BM aspirate purpose

used to diagnose and stage hematologic and non-heme disorders

used to obtain ancillary tests and evaluates presence of megakaryocytes

used to investigate blood abnormalities

BM aspirate aids in the diagnosis of heme/non-heme disorders such as

myeloproliferative disease

anemias/leukemias

lymphomas

when are wright stains used and what does the stain show?

BM aspirations

shows morphology and BM distribution of different types of cells

Wright stain: eosin

binds to positively charged molecules

acidic dye

binds to basic structures

pink to red

wright stain: methylene blue

stains negatively charged molecules

basic dye

binds to acidic molecules

blue

eosinophils stain what color with the Wright stain?

red

eosin dye reacts with:

hemoglobin

methelyne dye reacts with:

nuclear DNA and cytoplasmic RNA

basophils stain what color with the Wright stain?

purple-black

neutrophils stain what color with the Wright stain?

purple-blue

what stain should be used for ferric iron detection within tissues?

prussian blue

what pigment does myeloperoxidase stain produce?

brown-black

Myeloperoxidase stain detects all of the following cells EXCEPT

eosinophils