in the test system, estimation of approximate concentration of

fibrinogen cannot be made from the initial clotting time alone

but must be also made from observations of the consistency

and character of the clot at 60 seconds. At 60 seconds, samples

with normal fibrinogen levels will form a firm clot that adheres

to the walls of the test tube when the tube is inverted. If either

of these parameters are not met, (i.e. clotting time below

15 seconds or formation of a firm adhering clot after inversion

of the test tube) abnormality (less than 100 mg%) of the

fibrinogen reactivity should be suspected. In such cases

quantitative estimation of fibrinogen using Fibroquant is

strongly recommended.

Expected Values

A normal value using Fibroscreen reagent is the formation

of a solid gel clot in 5-15 seconds, which adheres to the test

tube wall on inversion at 60 seconds.

Remarks

1. Fibroscreen thrombin time remains normal in

deficiencies of factor XIII (fibrin stabilizing factor).

INTERPRETATION OF FIRST LINE TESTS:

Test Condition

PT APTT TT Platelet count

N N N N Disorder of platelet function, factor XIII deficiency, disorder of vascular hemostasis,

normal hemostasis

Long N N N Factor VII deficiency, early oral anticoagulation

N Long N N Factor VIII: C, IX, XI, XII, prekallikrein, HMWK deficiency,von Willebrand’s disease,

circulating anticoagulant

Long Long N N Vitamin K deficiency, oral anticoagulants factor V, VII and II deficiency

Long Long N N Heparin, liver disease, fibrinogen deficiency, hyperfibrinolysis

Long Long N N Thrombocytopenia

Long Long N Low Massive transfusion, liver disease

Long Long Long Low DIC, acute liver disease

N-Normal

Clinical Hematology: Bleeding Disorders 299

2. Fibrin gels may form in plasma with a fibrinogen

concentration below normal. However, these gels are

not firm, extrude considerable serum, and tend to

slide on the side walls of the tilted test tube. Careful

comparison of such gels with the firm clot with normal

plasma used as a control will eliminate the possibility

of confusion.

3. Fibroscreen thrombin time test is usually performed

first before any specific assays are attempted, when a

prolongation of (PT and APTT) cannot be explained.

FIBRINOGEN ESTIMATION-QUANTITATIVE

FIBROQUANT, REAGENT FOR QUANTITATIVE

ESTIMATION OF FIBRINOGEN

(Courtesy: Tulip Group of Companies)

Summary

At present there are known to be atleast eleven factors

in circulating blood, which are required for normal

hemostasis. Deficiency in any of these factors viz factors

I, II, V, VII, VIII, IX, X, XI and XIII, results in a notable

hemorrhagic condition, and the severity of the bleeding is

proportional to the degree of deficiency. In order to treat

the hemorrhagic condition, it is important to identify and

quantify the deficient factor.

Fibrinogen (Factor I) is a high molecular weight

glycoprotein synthesized in the liver, which plays an

important role in hemostasis. For normal hemostasis to

occur in response to injury or tissue damage, a sufficient

concentration of fibrinogen must be present in plasma.

Fibrinogen is converted into fibrin by the action of

thrombin and is a key component of clot formation.

Fibroquant kit contains lyophilized thrombin and

fibrinogen calibrator to determine the quantitative

reactivity of fibrinogen. Since the reagent system contains

heparin neutralizing substances, heparin levels up to

0.4 IU/mL does not interfere with test results.

When used as a front line test with PT, APTT, platelet

count and thrombin time, fibrinogen assay helps in

investigating acute hemostatic failure.

Reagent