Heme Lab Final Review Complete

Clinical significance of Prolonged Bleeding Time

Indicates primary hemostasis issues like dysfunctional platelets or decreased platelet count.

What are the 2 primary bleeding time methods

Ivy
Duke

Ivy Method

Most common bleeding time method using a blood pressure cuff.

Duke Method

less invasive bleeding time method without a blood pressure cuff.

Manual Platelet Count

Counting platelets in multiple fields and calculating the average number per field.

Manual platelet count steps

Count plts in one HP.
Move to another field and count.
5-10 diff fields need to be counted.
Calculate avg number of plts per field.
Multiple your avg by 17,000

What Causes Errors in Automated Platelet Counts

Microcytes and schistocytes may be miscounted as platelets

Platelet clumps or large platelets can be miscounted as white or red blood cells.

Increasing Blood Smear Angle will

make a thicker, shorter smear.

Decreasing Blood Smear Angle will

Make thinner, longer smear

Cause of blue or dark Blood Smear Stain

too thick film
prolonged staining inadequate washing
high pH

Causes of too pink or light of a blood smear stain

Insufficient staining time
Prolonged washing time
Too low pH of stain or buffer

Coagulation Testing Specimen of Choice

Citrated plasma (light blue top).

PT Test Reagents

Tissue factor and calcium.

APTT Test Reagents

Phospholipid-rich preparation
Activator
Calcium chloride.

ACLTOP Coag Testing Principles

Turbidimetric, chromogenic, and immunologic.

How is fibrin clot detected by turbidemetry?

As clot formation takes place, light transmission decreases

Direct chromogenic measurement

Analyte acts directly on specific chromogenic substrate (Protein C)

Indirect chromogenic measurement

analyte of interest reacts under optimized test conditions.
Measures residual enzyme activity then measured using spec synthetic substrate conjugated with chromophore (e.g. heparin, antithrombin).

Immunological vs Turbidimetric are similar except that

Immunological measures Ag-Ab immune complexes.

INR Calculation

Standardizes results for patients on Coumadin

Increased INR indicates

Warfarin/Coumadin use.

Urea test result for normal sample

clot will not be dissolved after 24 hours

Urea solubility test principle

determines if pt sample is factor XIII deficient by placing clot in 5m urea

Urea test result for factor XIII deficiency

clot will dissolve in <24 hours

D-Dimer Formation

Cross-linked D fragments; increased D-dimer indicates cross-linked fibrin breakdown.

FDP Latex Agglutination detects

fibrinogen and fibrin degradation products

D-Dimer assay is specific for

blood-clotting problems.

Stabilized fibrin clot is degraded (support Dx of DIC)

What is the reagent of the FDP latex agglutination assay?

PT

Prolonged PT factors

VII

Prolonged PTT factors

XII, XI, IX, VIII

Prolonged PT and PTT

X, V, II, I

ESR principle

Erythrocyte Sedimentation Rate

how fast the RBCs settle down the tube from plasma.

ESR Monitoring is used for

Rheumatoid arthritis, malignancy, multiple myeloma, bacterial infection, inflammatory disease

What can cause false positives in ESR

anemias, pregnancy, hyperfibrinogenemia states, increase in Igs, poikilocytosis

Cyanmethemoglobin Method principle

Manual hgb determination method using color intensity.

Erythrocytes are lysed by a stomatolytic agent in the presence of surfactant.

hgb released into solution.

hgb oxidized by methemoglobin by ferricyanide.

Methemoglobin is converted to stable cyanmethemoglobin by addition of KCN.

abs measured.
color intensity proportional to hgb conc.

WBC Count Formula using hematocytometer

WBC count = [WBC counted (N)/Volume (V)] X dilution factor

Volume = 4 X (1 X 1 X .1) = 0.4 mm^3

WBC Count = (N/V) X dilution factor = (N/0.4) X 20

RBC Count Formula using hematocytometer

RBC count= [RBC counted (N)/volume (V)] X dilution factor

Volume= 5 X (0.2 X 0.2 X 0.1) =0.02 mm3

RBC count = (N/V) X dilution factor = (N/0.02) X 200

VCS System of cell counting components

Volume, Conductivity, Scatter

VCS Volume principle

VCS utilizes the Coulter Principle of direct current (DC) impedance to physically measure the volume. This method accurately sizes all cell types regardless of their orientation in the light path.

VCS Conductivity principle

Alternating current short circuits the bipolar lipid layer of the membrane. Highfrequency electromagnetic probe determines the conductivity. Collects internal structure information, including chemical composition and nuclear volume.

VCS Scatter principle

Laser beam technology is used to scatter light. Multiple angle light scatter signals are collected an measured. Measures cellular granularity, nuclear lobularity, and cell surface structure.

How are RBC morpholologies quantified?

1+ - 4+

Band

Platelet

Seg

Eosinophil

Basophil

Monocyte

Lymphocyte

WBC (Total)

3.6-10.6 x 10^3/µL.

Neutrophils (absolute)

1.7-7.5 x 10^3/µL.

Neutrophils (relative)

50-70%.

Lymphocytes (absolute)

1.0-3.2 x 10^3/µL.

Lymphocytes (relative)

18-42%.

Monocytes (absolute)

0.1-1.3 x 10^3/µL.

Monocytes (relative)

2-11%

Eosinophils (absolute)

0-0.3 x 10^3/µL.

Eosinophils (relative)

1-3%.

Basophils (absolute)

0-0.2 x 10^3/µL.

Basophils (relative)

0-2%.