Lecture 1: Proper Sample Storage & Submission

What are the three blood sample types?

whole blood, serum, plasma

What sample type represents an unspun, non-clotted sample, ±anticoagulant?

whole blood

What sample type is the fluid fraction of whole blood obtained from an anticoagulated sample?

plasma

What sample type is the fluid fraction of whole blood obtained from a clotted sample?

serum

What sample type is used for a CBC?

whole blood

What sample type is used for chemistry?

plasma or serum

What does a plasma sample have that a serum sample lacks?

buffy coat

What is the buffy coat in a plasma sample?

WBCs

Serum = plasma - __________?

fibrinogen

What are the three layers of a plasma sample?

blood plasma, buffy coat (WBCs), RBCs

What are the layers of a serum sample?

serum, clot

What may cause hemolysis in a blood sample?

traumatic venipuncture or plunging syringe when filling collection tubes

Why should blood samples be transferred into tubes promptly?

coagulation

Traumatic venipuncture may introduce hemolysis and/or artificially reduce __________.

platelet counts

What blood tubes should you fill last and why?

purple top tubes to avoid EDTA contamination

What must be done when filling anticoagulant tubes?

ensure proper volume and prompt, gentle tube inversion for mixing

What are the three types of anticoagulant tubes?

EDTA, heparin, citrate

What blood tube prevents coagulation by chelating calcium?

EDTA- purple top

How does a heparin (green top) blood tube prevent coagulation?

inhibits coagulation by potentiating antithrombin

What is a purple top tube used for and why?

CBC, it is gentler on cells

What is a green top tube used for?

plasma biochemistry

What is a blue top tube used for?

coagulation testing

How does a citrate (blue top) tube prevent coagulation?

reversibly prevents coagulation by weakly chelating calcium

What are the two types of plain tubes?

red and white top

What blood tube is species dependent clotting time prior to centrifugation and used for serum biochemistry?

red top

What is a tiger top tube?

serum separator tube

How does a tiger top tube work?

• contains gel with intermediate density between cells and serum or plasma

• upon centrifugation, the fluid fraction will be separated from cell fraction, preventing leeching of certain analytes into the cell fraction

How long must a tube with clot activator with gel be allowed to let clot for?

30 mins

What issue occurred in each of these samples?

R: hemolysis

M: icterus

L: lipemia

What effect does hemolysis have on the appearance of a plasma/serum sample?

results in free hemoglobin and subsequent red discoloration

What effect does lipemia have on the appearance of a plasma/serum sample?

results in a lactescent appearance (milky)

What effect does icterus have on the appearance of a plasma/serum sample?

represents elevated bilirubin and yellow discoloration

Why should small animal patients ideally be fasted for blood draws?

lipemia

True or false: large animal plasma and serum naturally have a moderately yellow appearance.

true

What effect does in vitro hemolysis have on CBC results?

falsely decreases PCV, HCT, and RBC

What effect does in vitro or in vivo intravascular hemolysis have on CBC results?

• falsely decreased PCV, HCT, and RBC

• MCHC falsely increased

• ghost erythrocytes from intravascular hemolysis may be falsely counted as platelets, increasing PLT

• refractometric protein becomes difficult to read

What effect does in vitro or in vivo intravascular hemolysis have on chemistry results?

• spectrophotometric interference and inhibition of chemical rxns

• increase in intra-RBC analytes (K, phosphorus, ALT, LDH, Mg)

• minimal to mild increase in CK enzymatic activity

What effect does in vitro or in vivo intravascular hemolysis have on electrophoresis results?

severe hemolysis can cause beta globulin spikes

What effect does interference from lipemia have on CBC results?

• falsely increases HGB and subsequently MCHC

• large lipid aggregates may be falsely counted as platelets, increasing PLT, or potentially leukocytes, increasing WBC

• falsely increase refractrometric protein

What effect does interference from lipemia have on chemistry results?

• spectrophotometric interference

• proportional decrease in Na & Cl, slight decrease in K

What change in plasma/serum appearance can lipemia promote?

in vitro hemolysis

Why should samples with interference from lipemia be refrigerated?

to precipitate out the lipid, allowing collection of less lipemic serum/plasma

What effect does interference from icterus have on CBC results?

little to no effect

What effect does interference from icterus have on chemistry results?

marked to severe hyperbilirubinemia falsely decreases biuret total protein and creatinine, respectively