CH 10 CBC and Peripheral Blood Smear

What does hematocrit (Hct) measure and what is the equation to calculate it?

Measures RBC volume within whole blood

Hct % = (MCV * RBC)/10

What do the 3 RBC indices (MCV, MCH, and MCHC)

1. measure

2. are they measured directly/calculated on automation

3. equation to calculate

MCV: measures average volume of individual RBC’s. Measured directly. MCV = (Hct*10)/RBC

MCH: measures average weight of Hgb in individual RBC’s. Calculated. MCH = (Hgb*10)/RBC

MCHC: measures ratio of Hgb mass to volume. Calculated. MCHC = (Hgb*100)/Hct

What does the MCHC indicate?

Whether RBC population is normochromic, hypochromic, or hyperchromic

What does the red cell distribution width (RDW) describe and what does >14.5% RDW values indicate?

Describes the variation in red cell size

>14.5% = increased heterogeneity of RBC size (anisocytosis)

What is the difference between a manual and automated WBC differential?

manual: measures 100 WBC @50x and reported as a %

automated: 1000+ WBC classified by flow cytometry and reported as a %W

How is the absolute cell type concentration for WBC’s calculated?

WBC count * cell type %

What are the 2 pathologic conditions leading to RBC stacking or aggregation?

1. cold agglutinins: IgM Abs bind to RBC Ags → RBC agglutination @ lower temps

2. Rouleaux: aligned RBC’s seen in an increase of fibrinogen or globulins

What are the 3 causes of a decreased platelet count on a blood smear?

1. platelet clumps @ outer edge of smear

2. platelet satelliteism to neutrophils

3. fibrin strands from blood coagulation

At what power magnification are WBC differentials, platelet estimates, and RBC morphology assessment performed at?

WBC differentials: 50x oil

Platelet estimates + RBC morphology assessments: 100x oil

What is the definition of anisocytosis? What measurement may indicate anisocytosis?

variation of red cell size

RDW >14.5%

How are RBC sizes evaluated microscopically?

By comparing RBC’s to the nucleus of a normal small lymphocyte (~ same size)

What is the term for nonspecific variation in shapes or RBC’s? And what is it characteristic of?

poikilocytosis

characteristic of specific underlying disorders like thermal burns, IDA, TTP, etc

What is the term for small spherical cells with irregular thornlike projections?

acanthocytes (spur cells)

What is the term for bulls-eye cells?

Codocytes (target cells)

What is the term for cells with an elongation on one end? When are these cells formed?

Dacrocyte (teardrop cells)

When extramedullary erythropoiesis occurs in liver or spleen

What is the term for microcytic RBC’s with regular, spinelike projections?

Echinocytes (burr cells)

How can you differentiate acanthocytes from echinocytes?

Echinocytes have a central palor unlike acanthocytes

What is the term for pencil-like or cigar-like RBC’s?

elliptocyte/ovalocyte

What is the term for cells that have concavity on one side & 2 hornlike protrusions?

Keratocyte (helmet cell) or blister cell

How are helmet/blister cells produced?

by fibrin strand impalement → produces vacuole-like inclusion

What is the term for a cell that has more than 2 concavities?

Knizocyte

What is the term for thin, flat cells w/ a normal or larger diameter? Why does it’s SA-to-volume ratio increase?

Leptocyte

due to decrease of Hgb while increasing SA

What is the term for an RBC fragment that is usually microcytic w/ central area of pallor?

Schistocyte

What is the term for an RBC that has lost its bi-concavity due to decreased SA-to-volume ratio?

Spherocyte

Why are spherocytes the only cells that can be called hyperchromic?

Because of their increase in MCHC

What is the term for an RBC that has a slitlike area of pallor? What is it thought to be associated with?

stomatocyte

Inclusions will be done on Doc

Yes chef