Dilute Blood Clot Lysis Time

Principle

Plasmin inhibitors lose activity on dilution to a greater

extent than fibrinolytic activity. Whole blood is diluted with

a buffer solution and clotted by the addition of thrombin.

The clot is observed for lysis of the clot.

Requirements

1. Equipment for collection of blood sample

2. Test tube

3. Timer

4. Phosphate buffer, pH 7.4. To 1000 mL distilled water,

9.47 g Na2HPO4 is added and dissolved. This is mixed

with 250 mL distilled water containing 3.02 g KH2 PO4

5. Topical thrombin (or any other make) diluted to 100

units per mL with normal saline.

Method

1. Tubes containing 1.70 mL buffer and 0.1 mL thrombin

solution are placed in an ice bath.

2. Collect blood sample in standard manner using a

syringe that can deliver accurately 0.2 mL aliquots of

blood.

3. Add 0.2 mL blood to each of two tubes containing

buffer and thrombin and mix.

4. Clotting should occur promptly.

5. Tubes are placed in refrigerator (4°C) for 30 minutes

and then transferred to a water bath at 37°C.

302 Concise Book of Medical Laboratory Technology: Methods and Interpretations 6. The clots are observed for lysis. The endpoint is

fragmentation rather than complete dissolution of the

clot.

Result

Blood from a normal subject should not lyse in less than 6

to 10 hours. The test is qualitative. If results indicate rapid

lysis of the clot, more quantitative methods are necessary.

FDPS A QUALITATIVE AND SEMIQUANTITA- TIVE LATEX SLIDE TEST FOR DETECTING CROSS

LINKED FIBRIN DEGRADATION PRODUCTS IN

HUMAN PLASMA X-L FDP

(Courtesy: Tulip Group of Companies)

Summary

During coagulation sequence of reactions occur in the

body in response to variety of external and or internal

stimuli. The enzymatic cascade reaction terminates in

the conversion of fibrinogen to fibrin, by the enzyme

thrombin. The fibrin gel is then converted to a stable fibrin

clot by thrombin activated factor XIII.

Finally, the fibrin network is dissolved by the enzyme

plasmin to generate cross-linked fibrin degradation

products (XL FDP). D dimer comprising of two D fragments

cross linked together, is the smallest plasmin resistant

molecular unit present within XL FDP. Detection of D

dimer is invaluable as a diagnostic marker for thrombotic

conditions such as disseminated intravascular coagulation

(DIC), deep vein thrombosis (DVT) and pulmonary

embolism (PE). D dimer levels can also be used to monitor

thrombolytic therapy with tPA and with streptokinase,

thrombotic complications in pregnancy, acute myocardial

infarction, sickle cell crisis, severe septic infections, liver

disease, DIC accompanying snake bite and prognosis and

response to therapy in cancer.

Reagent

1. XL FDP reagent: A uniform suspension of polystyrene

latex particles coated with mouse monoclonal anti

D-dimer antibody (DD-3B6/22). The reagent is

standardized to detect XL FDP > 200 ng/mL.

2. Positive control, reactive with XL FDP latex reagent.

3. Negative control, non-reactive with XL FDP latex

reagent.

4. Phosphate buffer, for performing semi-quantitative test.