Page 714 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

698 PART 8 ■ Fundamentals of Hematological Analysis

COAGULATION PROCEDURES (continued)

TABLE 32.5 Probable Coagulation De ciencies Based on APTT and PT Test Results

De cient Factor

Test V VII VIII IX X XI or XII

PT Abnormal Abnormal Normal Normal Abnormal Normal

APTT Abnormal Normal Abnormal Abnormal Abnormal Abnormal

Adsorbed plasma Corrects No change Corrects No change No change Corrects

Aged serum No change Corrects No change Corrects Corrects Corrects

PT, prothrombin time; APTT, activated partial thromboplastin time.

Specimen Reporting Results

Fresh plasma rom citrate whole bloo is pre erre , Re erence values range rom 10 to 15 secon s. Report both

although oxalate plasma may be use . T e sample shoul the patient an control specimens in secon s. An ol er alter-

be centri uge promptly a er collection, with the plasma native metho o reporting is to express the percentage o

remove rom the erythrocytes. Plasma may be store or patient activity. T is is calculate as

several hours at 2°C to 6°C be ore testing.
Control time secon s)
(
p
0
10
Reagents, Supplies, and Equipment × = % activity o patient
Patient’s time secon s)
(
1. T romboplastin
2. 12 × 75-mm test tubes Clinical Applications

3. Pipettes: 0.1 mL (100 µL) T is test epen s on the activity o actors VII, V, X, II, an

4. 37°C water bath or heat block I. A ef ciency o any o these may pro uce a 3- to 4-secon

5. Stopwatch prolongation in the test ( able 32.5).

6. Nichrome loop

Quality Control BIBLIOGRAPHY

Normal an abnormal citrate or oxalate test plasma shoul

be run with each patient assay or test batch. Provi e on this book’s companion Web site at http://thepoint.

lww.com/ urgeon6e.
Procedure

Tis proce ure is commonly per orme using automate THROMBIN TIME

equipment. However, in some cases, a manual proce ure may Principle

be esire .
Te thrombin time test etermines the rate o thrombin-

1. Prewarm plasma at 37°C or a minimum o 2 minutes an in uce cleavage o f brinogen to f brin monomers an the

a maximum o 10 minutes. subsequent polymerization o hy rogen-bon e f brin poly-

2. Prewarm thromboplastin at 37°C or a minimum o 2 mers. Clinically, extremely low f brinogen levels, abnormal

minutes an a maximum o 60 minutes. fbrinogen thrombin inhibitors, an high concentrations

3. A 0.1 mL o plasma to 0.2 mL o thromboplastin. I per- o immunoglobulin (e.g., myeloma proteins) will pro uce

orming this proce ure manually, pipette quickly. Start a abnormal results. T e presence o heparin an high concen-

stopwatch simultaneously. trations o f brin-f brinogen egra ation pro ucts will also

4. Using the nichrome loop technique, the loop is swept prolong the time. T is proce ure is particularly use ul i

through the mixture at 2 sweeps per secon until the f rst other parameters, such as the AP an P , are prolonge .

stran o f brin appears. T e tube may also be tilte using T is proce ure, in CLSI ormat, is provi e on this book’s

a magnif er to observe clot ormation. companion Web site at http://thepoint.lww.com/ urgeon6e.

5. Repeat this proce ure in uplicate or all specimens, Re er to the re erence values on the insi e back cover as

inclu ing controls. T e uplicate results shoul be within well as a itional proce ures at http://thepoint.lww.com/

1 secon o one another. urgeon6e.