Serum Sample and Test Measures

If a serum sample cannot be tested for 4 hours, it should be:

• Kept at room temperature

• Refrigerated at 2-8°C

• Frozen at -20°C

• Discarded and recollected

The sensitivity of a test measures:

• True negatives

• True positives

• False positives

• False negatives

What must be done if complement interferes with a test?

• Freeze and thaw before testing

• Heat at 56°C for 30 min

• Add anticoagulant

• Centrifuge at 3,000 g

A hemolyzed serum sample:

• Is normal and acceptable

• May interfere with testing

• Indicates bacterial contamination

• Is required for immunoassays

The law of mass action states:

• Antibody and antigen are always bound

• Free and bound reactants are in equilibrium

• Antibody binding sites equal antigen binding sites

• Free reactants bind randomly

The best sensitivity in an assay is associated with:

• K = 1

• K = 2

• K = 4

• K = 9

Passive agglutination occurs when:

• Antigen is naturally found on a particle

• Antigen is artificially bound to particles

• Antibody is attached to particles

• The reaction is competitive

Nephelometry measures:

• Absorbed light

• Scattered light

• Emitted light

• Reflected light

The antibody class requiring enhancement to visualize agglutination:

• IgM

• IgG

• IgA

• IgE

ELISA results are:

• Directly proportional to enzyme activity

• Indirectly proportional to enzyme activity

• Competitive and always indirect

• Affected only by antigen concentration