Page 713 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

CHAPTER 32 ■ Laboratory Manual: Manual Procedures in Hematology 697

COAGULATION PROCEDURES (continued)

with anti–f brin split pro ucts. I f brin split pro ucts are

TABLE 32.4 Mixing Studies present, agglutination will occur. I these pro ucts are present

in increase amounts with normal hepatic an renal unc-

PT or APTT tion, it is assume that a recent f brinolytic event has taken

After Mixing place or is taking place. Clinically, elevate results emon-

PT or and Waiting strate that the activation o plasmin has occurre or is occur-

APTT After for a 2-Hour ring, such as in primary f brinolysis an DIC with secon ary

Inhibitor or Immediate Incubation at fbrinolysis.

De ciency Mixing 37°C T is proce ure, in CLSI ormat, is provi e on this book’s
companion Web site at http://thepoint.lww.com/ urgeon6e.

Factor de ciency Corrected Corrected

Factor VIII inhibitor Corrected Not corrected FIBRINOGEN ASSAY: METHOD CLOTTING ASSAY

Factor V (Leiden) Not corrected Not corrected Principle

inhibitor
Fibrogen thrombin actor II → ibrin
Lupus anticoagulant Not corrected Not corrected

When plasma is ilute an clotte with excess thrombin,

kininogen [HMWK]; or prekallikrein [PK]) or in the the f brinogen concentration is inversely proportional to the

common pathway (also prolonge P ) such as actors II, V, clotting time, yiel ing a linear relationship when plotte on

an X. Def ciency o actors VIII, IX, an XI will present log-log paper. Fibrinogen assays are use ul in etecting ef -

with blee ing. Def ciency o actor XII, or prekallikrein, will ciencies o f brinogen an in etecting an alteration in the

not increase blee ing risk but may increase thrombotic risk. conversion o f brinogen to f brin.
T is proce ure, in CLSI ormat, is provi e on this book’s

Substitution Studies companion Web site at http://thepoint.lww.com/ urgeon6e.

Substitution stu ies an actor assays can be use to i enti y Platelet Aggregation

specif c coagulation actor ef ciencies. See Chapter 25.

Principle PROTAMINE SULFATE ASSAY

Substitution stu ies may be per orme using a sorbe Principle

plasma an age serum with the AP to i enti y ef cien-

cies o bloo coagulation. Substitution stu ies may also be Protamine is use to neutralize the e ects o heparin. I prot-

per orme using a sorbe plasma with the P to i enti y a amine is a ministere in excess therapeutically, it is capable

actor VII ef ciency. o inter ering with actor IX activity an thromboplastin gen-
eration. A positive result in icates the inappropriate presence

Speci c Factor Assays o intravascular f brin monomers. (See Chapter 25 or more

Principle in ormation on platelet aggregation.)

Factor assays are base on the ability o the plasma in ques- T is proce ure, in CLSI ormat, is provi e on this book’s

tion to correct a actor- ef cient substrate, such as actor VIII. companion Web site at http://thepoint.lww.com/ urgeon6e.

Te actual assay is the same as the AP with the excep-

tion o the actor- ef cient substrate. I entif cation o specif c PROTHROMBIN TIME

actor ef ciencies is valuable in both the iagnosis an the Principle

treatment o patients. T is basic proce ure involves a ing plasma to an excess o

T is proce ure, in CLSI ormat, is provi e on this book’s extrinsic thromboplastin-calcium substrate. T romboplastin

companion Web site at http://thepoint.lww.com/ urgeon6e. is erive rom tissues that supply phospholipoprotein, such

as animal brain. T e length o time require to orm a f brin

FIBRIN SPLIT PRODUCTS: THROMBO- clot is measure in secon s.

WELLCOTEST METHOD Clinically, this proce ure is use to monitor oral antico-

agulant therapy, as a screening test in the iagnosis o coag-
Principle ulation ef ciencies, an as a component o a liver prof le

Whole bloo is a e to thrombin (to ensure complete assessment. Prolonge results can in icate a ef ciency o

clotting) an soya bean enzyme inhibitors (to prevent any one or more actors in the extrinsic pathway: actors VII, X,

break own o f brin). A er incubation, the patient’s serum is an V an actor II or I. T e presence o an inhibitor will also

ilute an mixe with latex particles that have been coate pro uce prolonge values.

(continued)