mlt 210 - manual and semiautomated testing

white cell counts

four large corner squares are typically counted'

typical dilution for whole blood is 1:20

diluting fluids used to lyse RBCs (1% ammonium oxalate, 3% acetic acid, 1% hydrochloric acid)

red cell counts

typical dilution for whole blood is 1:100

diluting fluid is isotonic saline to prevent lysis

not typically performed

platelet counts

25 small squares of the middle large square typically counted

typical dilution 1:100

diluting fluid is 1% ammonium oxalate to lyse non nucleated RBCs

cyanmethemoglobin method

hemoglobin is oxidized to methemoglobin by potassium ferricyanide

absorbance is directly proportional to hemoglobin concentration

rule of three

if a patient has normal cells, they should follow this

RBCs x 3 = hemoglobin (+ or - 1.5 g/dL)

hemoglobin x 3 = hematocrit (+ or - 3%)

hematocrit

packed cell volume

uses centrifuge

MCV

mean cell volume

average cell volume of red cell

less than 80 fL = microcytic, more than 100 fL = macrocytic

MCH

mean cell hemoglobin

average weight of hemoglobin in an RBC

MCHC

mean cell hemoglobin concentration

average concentration of hemoglobin in each individual RBC (g/dL)

ref range: 32-36 g/dL

spherocytes

can cause high MCHC

cells appear round and full

lipemia

can cause high MCHC

falsely elevated hemoglobin value due to fat

correct with saline replacement and repeat testing

cold agglutin

can cause high MCHC

cells clump together at room temp

correct by incubating at 37C and repeat testing

reticulocytes

immature RBCs

contain RNA that can be stained

1000 RBCs are counted, and the percentage of those RBCs that are reticulocytes are determined

used to asses bone marrow function

erythrocyte sedimentation rate (ESR)

non specific test for inflammation

many things can cause it to be elevated

use EDTA anti-coagulated blood