CENTRIFUGATION OF SERUM AND PLASMA

Specimen Processing

Centrifugation and aliquot preparation (representative value of the actual specimen)

Centrifuge

instrument that spins blood tubes at a high relative centrifugal force to separate serum or plasma from the blood cells

plasma

centrifugation of anticoagulated blood

serum

centrifugation of clotted blood

2 hours

Specimens can be separated within how many hours after collection?

anti coagulated blood

• Can be separated immediately

• Collected from colored tap tubes except for red, yellow, or gold

clotted blood

• must be allowed to be fully clotted before separation

• Collected from red, yellow, or gold tap tubes

• May take from 5 minutes (with clot activator) to 1 hour (plain tubes)

Hematology specimens should never centrifuge

• Ex. complete blood count, reticulocyte counts, red blood cell count, and white blood cell count

should hematology specimen be centrifuged?

Relative Centrifugal Force (RCF)

expressed as gravity (g) and is determined by the radius of the rotor head and the speed of rotation (revolutions per minute rpm]).

• Red blood cells at the bottom

• White blood cells and platelets at the middle (buffy coat)

• Plasma at the top

composition of anticoagulated blood

• No red blood cells and white blood cells differentiation

• Only clotted blood at the bottom and serum at the top (serum is plasma without fibrinogen)

composition of clotted blood

balancer tube

empty or unused test tube that filled with distilled or saline water to the same amount of blood the sample has

refrigerator

general storage of specimens

8 hours

Separated serum or plasma may remain at room temperature for how many hours?

place the liquid component to the other test tube

in storing specimens, if the tube does not have any separator gel, what should you do?

light blue tubes

tubes for coagulation

Specimens for Activated Partial Thromboplastin
Time (APTT)

• Stable at room temperature for 4 hours

• If patient is receiving heparin therapy, plasma must be separated from cells within 1 hour after collection, tested within 4 hours

all other coagulation tests

• Performed within 4 hours of collection

• If cannot be tested within 4 hours, platelet poor plasma must be separated, and red cells can be frozen within 1 hour of collection (can be kept for 1 year)

lavender or pink tubes

tubes for hematology

Blood smears from EDTA tubes

• Performed within 1 hour of collection

• The longer it stands, the greater possibility of having cellular distortion

EDTA specimens for complete blood counts (CBCs)

• Stable for 24 hours at room temperature; should be analyzed within 6 hours

• EDTA blood collected in microcontainers must be tested within 4 hours

Reticulocyte counts collected in EDTA tubes

• Reticulocyte count is a procedure of getting the number of reticulocytes (immature red blood cells)

• Should be analyzed within 6 hours at room temperature

• Should be analyzed within 72 hours when refrigerated

Specimens for glucose tests collected in sodium fluoride tubes

• Stable for 24 hours at room temperature

• Stable for 48 hours when refrigerated

grey tubes

tube for clinical chemistry

• Specimens for Activated Partial Thromboplastin Time (APTT)

• All other coagulation tests

Coagulation (Light Blue Tubes) Tests

• Blood smears from EDTA tubes

• EDTA specimens for complete blood counts (CBCs)

• Reticulocyte counts collected in EDTA tubes

Hematology (Lavender or Pink Tubes)

• Specimens for glucose tests collected in sodium fluoride tubes

Clinical Chemistry (Grey Tubes)