MODULE I - OVERVIEW OF CLINICAL HEME

WEEK 01 - plasma & formed elements

what is hematology?

the study of blood & blood forming organs

what are the two component of blood?

• plasma: watery, straw colored liquid containing formed elements

• formed elements: cellular components - erythrocytes, leukocytes, thrombocytes (cell fragments important for clotting)

define phlebotomy

the process of drawing blood from patients for diagnostic testing

describe the process of phlebtomoy.

• set up with tourniquet, tubes, patient information, cotton, needle (gauge dependent on procedure & patient - smaller gauge = larger needle), ppe

• tie the tourniquet 3-4 inches above the antecubital, make sure it is disinfected

• uncap needle & inspect bevel for burrs

• place thumb on forearm in line with chosen vein (median cubital is great for blood draws, bad for IVs - cephalic vein is great for IVs) & poll taut to anchor

• advance needle into vein with bevel at 15-30° angle & insert quickly/smooth

• insert tubes in order of draw (yellow, light blue, red, gold, green, purple, gray) using C method

• on last tube, remove the tourniquet & remove needle simultaneously placing cotten

• invert 2-3 times each tube

describe the order of draw - include additives

yellow - SPS

light blue - sodium citrate

red - clot activator

gold - SST

green - heparin

purple - EDTA (ethylenediaminetetra-acetic acid) - anticoagulant to preserve blood in liquid state (NO CLOTTING)

• EDTA chelates (actively binds) calcium to keep from clotting

grey - sodium fluoride

what is a waste tube?

in a winged butterfly needle there is air inside. light blue (sodium citrate) tubes require an exact ratio of blood to additive. attach a tube with no additive to remove air

what elements make up whole blood?

55% plasma:

• 91% water

• 7% proteins (hormones, albumin, clotting proteins, antibodies)

• 2% solutes (sodium, calcium, chloride, etc)

45% formed elements

• >99% erythrocytes

• <1% leukocytes

• <1% platelets

describe erythrocytes (rbc)

• small, non-nucleated cells made of hemoglobin & water used to transport oxygen & remove CO2 waste

• biconcave

  • central pallor makes up 1/3 of the cell size & shape, allows for proper gas exchange

• live & die in 120 days

• derived from a reticulocyte

describe thrombocytes (platelets)

• small, acellular (not a cell, cell fragment), circulating nuclear membrane bound structures derived from megakaryocyte

• bioconvex shape

• become plump in the presence of EDTA anticoagulant

• important for blood coagulation, inflammation & allergic reactions

name the types & subtypes of leukocytes (wbcs)

• granulocytes: leukocytes containing cytoplasmic granules that contain microbe-killing toxins

  • neutrophils

  • basophils

  • eosinophils

• agranulocytes: agranular, not containing cytoplasmic granules

  • lymphocytes

  • monocytes

• protect us against foreign cells, organisms, & materials

what are neutrophils? what do they look like?

• granulocyte - cytoplasmic granules

• “neutral liking” - neutral rxn to stain, show more purplish granules that do not stick out as much

• polymorphonuclear cells (PMN) - nucleus is never the same

• circulating phagocytic cell, mostly in circulatory system

• important in innate immunity

what are eosinophils? what do they look like?

• granulocyte

• “eosin stain” - pinkish

• circulating phagocytic cells

• important in innate immunity from worm parasites (helminths)

what are basophils? what do they look like?

• granulocyte

• “big blue granules”

• circulating non-phagocytic cells

• important in innate immunity

• allergic responses

what are monocytes? what do they look like?

• agranulocytes

• mononuclear phagocytic wbc that circulates in the blood for ~8hrs before moving to the tissues where it matures into a macrophage

• important for innate & acquired immunity

what are lymphocytes? what do they look like?

• agranulocyte

• small ring of cytoplasm

• small, motile mononuclear, nonphagocytic cells that circulate between blood & lymph.

• make up majority of lymphatic system

• important for acquired immunity

• T cells & B cells: adaptive immunity modulate specific immune response & produce antibodies

• NK cells “natural killer”: innate immunity, tumor surveillance

what are normal adult blood-cell counts?

what is a complete blood count? what tube is it collected in?

• calculation of rbs, wbcs, & plts in the blood

• purple top (EDTA)

what is a hemacytometer?

a quantitative method for determining the concentration of rbcs, wbcs, & plt in diluted blood

what are manual cbcs essential for?

• quality control checks

• low or abnormal counts

• body fluid counts (CSF, synovial, serous fluids)

• instrument backup or verification

what is the principle of a cbc?

a known dilution of blood is placed in a counting chamber of a known volume, and cells are counted under a microscope

describe the hemacytometer slide

• thick glass slide with 2 counting chambers etched with grid pattern (improved neubauer ruling)

• coverslip placed over chamber with a depth of 0.2mm

what is the improved neubauer ruling?

• describes the grid layout on a hemacytometer

• each ruled area = 3 mm x 3mm (9mm²)

  • central square: 1mm² divided into 25 large squares each with 16 small squares - RBCs & PLTS @ 40x

  • four corner squares: each 1mm² with 16 small squares - WBCs @ 10x

  • each large square represents a volume of 0.1mm³ or 0.1uL

where on the grid of a hemacytometer do you not count cells?

cells touching bottom & right lines

what are the 3 rules to counting RBCs, WBCs, and PLTs? explain.

• different dilution factor

  • RBCs: 1:200

  • PLTs: 1:100

  • WBCs: 1:20

• different squares

  • RBCs: 4 corners & middle of central square

  • PLTs: all of central square

  • WBCs: 4 corners

• different magnification

  • RBCs & PLTs: 40x

  • WBC: 10x

what 2 equations can we use for hematcytometer counting?

• (# cells counted x dilution factor)/(area counted mm² x depth 0.1)

• (# cells counted x dilution factor x depth 10)/area counted mm²

• result: # cells/mm³

how do we convert mm³ to standard units (US)

• # cells/uL

• RBCs = # cells x 10^6 cell/uL

• PLTs & WBCs = # cells x 10³ cells/uL

how do we convert mm³ to international units (SI)?

• # cells/L

• RBCs: # cells x 10^12 cells/L

• PLTs & WBCs: # of cells x 10^9 cells/L

what is the normal range for rbcs in SI units (x10^12/L)

• male: 4.60 - 6.00

• female: 4.00 - 5.40

what is the normal range for plts in SI units (x10^9/L)?

male or female: 0.5 - 1.5

what is the normal range for wbcs in SI units (x10^9/L)

male or female: 4.5 - 11.5

what types of sources of error are there in manual cell counts?

• pre-analytical

• analytical

• post-analytical

describe pre-analytical sources of error

describe analytical sources of error

describe post-analytical sources of error