All the reagents contain 0.1% sodium azide as preservative.

Each batch of reagents undergoes rigorous quality

control at various stages of manufacture for its specificity,

sensitivity and performance.

Reagent Storage and Stability

1. Store the reagent at 2-8°C. Do not freeze.

2. The shelf-life of the reagent is as per the expiry date

mentioned on the reagent vial labels.

Principle

XL FDP slide test for detection of cross-linked fibrin

degradation products is based on the principle of

agglutination. The test specimen (plasma) is mixed with

XL FDP latex reagent. The sensitivity of the reagent is

~ 200 ng/mL, below which samples are negative and above

which samples give a positive agglutination reaction.

The crosslinked fibrin degradation products, D dimer,

D dimer E, and high molecular weight derivatives are all

recognized by Tulip XL FDP reagent incorporating the

monoclonal antibodies. No binding was found to the

fibrinogen degradation products XYD and E to 20 mg/L or

to fibrinogen up to 1000 mg/L.

Note

1. In vitro diagnostic reagent for laboratory and professional use only. Not for medicinal use.

2. The reagents contain 0.1% sodium azide as preservative.

Avoid contact with skin and mucosa. On disposal flush

with large quantities of water.

3. All the reagents derived from human source have

been tested for HBsAg and anti-HIV antibodies and

are found to be non-reactive. However, handle the

material as if infectious.

4. The reagent can be damaged due to microbial

contamination or on exposure to extreme temperature

conditions. It is recommended that the performance of

reagent be verified with positive and negative controls

supplied with the kit.

5. Shake the XL FDP latex reagent vial before use to

disperse the latex particles uniformly and improve test

readability.

6. Only a clean and dry glass slide must be used. Clean

the slide with distilled water and wipe dry.

Sample Collection and Preparation

No special preparation of the patient is required prior to

sample collection. Plasma samples are recommended for

use with XL FDP test. Fresh EDTA, citrate or heparinized

anticoagulated plasma specimens are suitable for

performing the test.

Clinical Hematology: Bleeding Disorders 303

Sample storage: 20–25°C — 8 hours

2–8°C — 4 days

Frozen (–20°C) — 2 months.

Thaw frozen specimens at 37°C and centrifuge plasma

before testing.

KIT Composition

1. XL FDP latex reagent, positive control, negative

control, PBS buffer.

2. Glass slide with six reaction circles, disposable sample

dispensing dropper, mixing sticks, rubber teat, package

insert.

Additional Material Required

Stopwatch, test tubes high intensity direct light source.

Test Procedure

Bring all the reagents and sample to room temperature

before performing the test.

Qualitative Method

1. Pipette one drop of plasma specimen onto the glass

slide using the disposable dropper provided with the

kit. Hold the dropper exactly in vertical position to

dispense the drop accurately.

2. Add one drop of XL FDP latex reagent adjacent to

the drop of plasma specimen, taking care to hold the

dropper in a vertical position while dispensing the

drop. Do not let the dropper tip touch the plasma

specimen on the slide.

3. Using a mixing stick, mix the plasma and latex reagent

uniformly over the entire circle.

4. Immediately start a stopwatch, rock the slide gently,

back and forth, and observing for agglutination

macroscopically at three minutes.

5. Do not read the test result beyond 3 minutes.

Semiquantitative Method

1. Using PBS buffer solution prepare serial dilutions of

the plasma sample 1:2, 1:4, 1:8, 1:16, 1:32 and so on.

2. Pipette each dilutions of plasma specimen on to the

separate reaction circles.

3. Add one drop of XL FDP latex reagent to each drop of

diluted plasma specimen on to the slide. Do not let the

dropper tip touch the diluted plasma specimen on the

slide.

4. Immediately start the stopwatch. Rock the slide

gently, back and forth, observing for agglutination

macroscopically at three minutes.

Interpretation of Results

Qualitative Method

¾ Agglutination is a positive result indicating D dimer

level above 200 ng/mL.

¾ No agglutination is a negative result indicating absence

of clinically significant D dimer levels in the plasma

specimen.

Semiquantitative Method

Agglutination in the highest plasma dilution corresponds

to the approximate amount of D dimer level in ng/mL.

To calculate D dimer level in ng/mL in the sample, use

the following formula,

D dimer level (ng/mL) = 200 × d

Where, d = highest dilution of plasma showing agglutination during the semi-quantitative test of the sample.

Note

Activation of the coagulation system with subsequent

microvascular fibrin deposition, and lysis has been reported

in diverse clinical conditions such as trauma, surgery,

inflammation and malignancy. Elevated levels of plasma XL

FDP may be expected to occur in such conditions.

Remarks

1. D dimer half-life is approximately 6 hours in circulation

of individuals with normal renal function. Patients

with stabilized clots and not undergoing active fibrin

deposition and plasmin activation may not give

detectable D dimer elevations.

2. In PE, larger the clot size, higher the expected level

of circulating D dimer. Conversely, the amount of D

dimer released from very small clots may be diluted by

the circulation and may not give a detectable increase.

3. Fibrinolysis is a highly regulated process and in

delicate dynamic balance. In case of hereditary,

acquired deficiency and dysfunction of fibrinogen, the

rate of fibrinolysis will be altered there by not giving a

detectable D dimer level.

4. As with any laboratory test, detection of elevated levels

of XL FDP in a specimen should be correlated with

clinical findings.

Screening Tests for Diagnosis of Procoagulant Deficiency

Principle

Most of the coagulation disorders can be classified on the

basis of the prothrombin time used in conjunction with the

partial thromboplastin time. The effect of BaSO4

-

adsorbed

304 Concise Book of Medical Laboratory Technology: Methods and Interpretations normal plasma on the results of the abnormal test is of

diagnostic importance.

Requirements

1. All reagents and equipment necessary for the prothrombin time and partial thromboplastin time.

2. BaSO4

–

 treated normal plasma.