Lab CE Course - Coagulation Inhibitors and Factor Deficiencies

40%

MINIMUM percentage of each coagulation factor present in a patient's plasma to produce a normal PT and aPTT

Factor deficiencies and coagulation inhibitors that prolong a PT and/or aPTT test result

Mixing studies may help to determine the presence of

1:1

Ratio of patient plasma to pooled normal plasma used in a mixing study

4 hours

A mixing study should be performed within what time frame following collection of the specimen?

True

A thrombin time will detect heparin in a patient's plasma so that heparin does not produce a false-positive aPTT mixing study result.

Anti-factor VIII inhibitor

ACQUIRED hemophilia A may be the result of which of the following conditions

slow-acting inhibitor

Both anti-factor VIII and lupus anticoagulant have been known to be

Collecting a specimen for aPTT testing from a heparinized vascular access device

Falsely prolonged aPTT test result

Corrected, Factor Deficiency

Initial PT: 23 sec Immediate Mixing Study PT: 12 sec Incubated Mixing Study PT: 13 sec Corrected or not-corrected? Factor deficiency or coagulation inhibitor?

Increased platelets in plasma sample

What may prevent the detection of lupus anticoagulant in a plasma sample if the blood used for testing is not centrifuged for a sufficient time?

You have not run a PT or aPTT on the new mix before incubating

When performing your mixing study, you aliquot your sample plasma and the pooled normal plasma to create your "mix". You then place the mix in a water bath to incubate for 90 minutes before testing your new mixed sample. What is the problem with the steps involved in the procedure above?

A pooled plasma from at least 20 healthy donors having normal PT/aPTT results

acceptable as the "normal" plasma reagent to use in a mixing study

Check for clots in the sample Check patient history Check for anticoagulant therapy

investigation of an initially prolonged PT test

II

may be deficient if both the PT and aPTT are prolonged

Lupus anticoagulant (anti-phospholipid antibody)

most common coagulation inhibitors

VII

prolongation of the PT test if the aPTT test is normal

Bethesda assay

quantify a coagulation inhibitor