Hematology: The Basic Function of Blood & Lab Values

Pathology

functions of blood

• delivery and transport of substances for cellular metabolism

  • O2, CO2, and other nutrients

• defense against microorganisms and injury

  • movement of immune elements

  • prevention of exsanguinations (bleeding out) through clotting

• maintain acid-base balance

  • homeostasis

plasma

55% of blood composition

• clotting factors

• albumin/proteins

• humoral immunity

• electrolytes

cellular component

45% of blood composition

• red blood cells (erythrocytes)

• white blood cells (lymphocytes)

• platelets (kind of)

blood composition

plasma, buffy coat (WBCs, PLTs), packed red cells

crow’s foot

white blood cell, hemoglobin, hematocrit, platelet

information in the CBC (complete blood count)

• white blood cell count (total leukocytes)

• lymphocyte percentage

• granulocyte percentage

• red blood cell count

• hemoglobin

• hematocrit

• mean corpuscular volume

• mean corpuscular hemoglobin

• mean corpuscular hemoglobin concentration

• red cell distribution width

• platelet count

reference range is age and sex dependent!

includes eos/basos/neutros/bands/blast

erythrocytes (RBC)

• abundant on a peripheral smear

• have a “central pallor” 1/3 the size of the cell

• about the size of a lymphocyte nucleus

• carries hemoglobin

about 120 days

lifespan of a red blood cell

• removed from circulation by reticuloendothelial cells, mostly within spleen

RBC count

• number of RBC in the PCV

• along with Hct, RBC can help determine the hematologic pathologies

adult normal RBC count

male: 4.7-6.1 million/ml

female: 4.2-5.4 million/ml

hematocrit

the percent of RBC in a given volume of whole blood

adult normal hematocrit values

male: 42-52%

female: 37-47%

fixed volume

size of the RBC determines RBC count in a

Hct

patients may have the same ____ but vastly different RBC counts

RBC

patients also may have the same ___ count but different Hct

mean corpuscle volume (MCV)

• average volume of 1 RBC

• derive from PCV/RBC count

• quite helpful in differentiating anemias

• measure of the size of the RBC

  • reference range: 80-100 fl

reticulocytes

• slightly immature form of RBC (baby rbcs!)

• reference range: 0.5-1.5%

• decrease seen in bone marrow failure

• increase seen when bone marrow is pumping out RBC at a higher rate than normal

hemoglobin

• transports O2 and CO2, high affinity for oxygen

• up to 300 molecules per RBC

• __ and hct rise or fall together

• is typically 1/3 of the hct

hemoglobin normal adult values

male: 14-18 g/dl

female: 12-16 g/dl

iron stores

• as “heme” provides the site for binding oxygen

• men have about 1000 mg and lose 1 mg/day

• women have about 300-400 mg and lose about 2mg/day particularly during menstruation

menstruating women, lactating women

are predisposed to iron deficiency and thereby anemia

mean corpuscular hemoglobin (MCH)

• amount of hemoglobin carried on 1 rbc

• derived from hgb/rbc count

  • reference range: 27-33 picograms/cell

mean corpuscular hemoglobin concentration (MCHC)

• percentage of hgb carried on 1 rbc

• derived from hgb/mcv

  • reference range: 33-36 g/dL

erythrocyte sedimentation rate (ESR)

• measure of how fast the RBCs sink to the bottom of a solution

• non-specific test for inflammation and inflammatory disorders

  • cancer, auto-immune disease, pregnancy and infections

• increased rate is caused by clumping of the RBCs due to proteins in the blood formed from the inflammatory cycle

• non-specific for diagnosis, but can be used for monitoring of disease progression or effectiveness of treatment

erythrocyte sedimentation rate reference ranges

male: 0-17 mm/hr

female: 1-25 mm/hr

leukocytes (WBC)

• defenders of the body against organisms that cause infection

  • kills microorganisms with enzymes contained within

• remove debris from host cells and offending organisms

  • phagocytosis of debris

• work specifically at tissue sites but are circulated via the blood

• broken up into granulocytes (neutrophils, eosinophils) and agranulocytes (monocytes, lymphocytes, nk cells)

leukocytes normal adult value

5,000-10,000

• less: something affecting bone marrow

• greater: infection

neutrophils

• most numerous of the WBCs (55% of leukocyte count)

• have large multi-lobated nuclei (2 to 5)

• are responsible for management of bacterial infection primarily

• respond to immune complexes and release non-specific cytotoxic material from their granule

• chief phagocytes in early inflammation

• immature neutrophils are “bands” or “stabs”, develop in 14 days

eosinophils

• less common WBC (1-4% of count)

• granules stain red

• mainly used for parasite management

• involved in the control of inflammatory process

• increased in asthma/allergy

agranulocytes

• powerful phagocytes

• lack the microorganism kililng enzymes of the granulocytes

• 3 major groups: monocytes, lymphocytes, NK cells

monocytes

• horseshoe shaped

• develop into macrophages at the site of inflammation

  • macrophages are the initiators of inflammatory response

lymphocytes

• large part of the WBC (36%)

• countless types but the major ones are T-cells and B-cells

NK cells

• attack cells infected by virus without prior exposure

• 5-10% of the WBC count

platelets

• disc shaped cytoplasmic fragments (not cells)

  • no nucleus or DNA

• responsible for part of the clotting cascade

• made in the bone marrow

• released and 1/3 go to the spleen, 2/3 are released in circulation

• life span 7-10 days

platelet count normal values

150,000-450,000

• less than 50,000/uL increases the risk of bleeding with trauma

• less than 10-30,000/uL increases risk of spontaneous bleeding