13-blood and tubes

erythrocytes

RBCs → biconcave, anucleated

carry oxygen and CO2 through body

composition of blood

55% plasma

1% platelets

45% RBCs

clotting samples yeild

serum and blood clot

non clotting samples yeild

plasma and RBCs (+ buffy layer)

or whole layer

clot activator tubes

red plastic and gold SST

what happens when blood clots

RBC, WBC, platelets aggregate

coagulation proteins are used

serum

no coagulation factors and fibrinogen present; preferred specimen

anti coagulant tubes

sodium citrate (blue)

Lithium heparin PST tube (green)

blue tube

sodium citrate tube

used for coagulation testing → PT, PTT, fibrinogen, D dimer, factor assays

requires 9:1 blood to anticoagulant

gold top

SST

for serum

need 30 mins to clot

has thixotropic gel to separate cellular content from serum → not good for large molecules

plastic red top

yields serum

clot activator → silica particles

good for large molecule tests → needs 30 mins to clot

light green tube

PST → lithium heparin

anticoagulant

has thixotropic gel

yields plasma

dark green tube

heparin → either lithium hep or sodium hep

used for whole blood chemistry and things like chromosome analysis

lilac tube

EDTA → chelates Ca

whole blood for CBC; ABO/Rh typing; Ab screening

If you had a full 4.5 mL PST tube and each test required 50 uL, roughly how many tests could you do, theoretically?

4.5 ml = 4500 ul

4500 ul x 0.55 (amount of plasma in blood) = 2475 ul

2475 / 50 uL

= 49.5 tests

icterus

hyperbilirubinemia → result in greenish decolorization of serum or plasma

royal blue top

for trace element testing

ACD yellow top

acid citrate dextrose → binds to Ca = no coagulation

dextrose → maintain RBC viability

whole blood sample

for DNA testing; CD4/CD8 ratio; HLA typing

gray top

potassium oxalate → precipitates Ca = no coagulation

sodium fluoride → inhibit glycolysis = preserve glucose up to 3 days

yields plasma

used for blood alc and lactate testing

black top

ESR tests

sodium citrate = anticoagulation

order of draw

blood culture → no contamination

sodium citrate → coagulation tests sensitive to interference

serum tubes → royal blue (trace element priority), red top, sst → red top glass has priority (no additives)

anticoagulated → pst, heparin, k2 EDTA royal blue, edta lavender, gray top

ESR