Method

1. The plasma under study is tested in the usual manner

by both the prothrombin time and the partial thromboplastin time.

2. Mix equal volumes of the test plasma and normal

control plasma. About 0.5 mL of the mixture is

needed.

3. Mix equal volumes of the test plasma and BaSO4

–

treated normal plasma. About 0.5 mL of the mixture

is needed.

4. Determine the prothrombin time and the partial

thromboplastin time each of the mixtures.

Results

1. If both the prothrombin time and the partial thromboplastin time are normal, it is doubtful that clinically

significant coagulation disorder is present.

2. If the normal plasma fails to correct an abnormal

prothrombin time or partial thromboplastin time, it is

likely that the patient has a circulating anticoagulant.

3. If normal plasma corrects either the prothrombin time

or the partial thromboplastin time, the presumptive

diagnosis is as indicated in the table.

4. Factor XII deficiency will have a pattern similar to that

of factor VIII deficiency. The correct diagnosis can

be further elucidated by the lack of a real bleeding

tendency in the factor XII deficiency. Definite diagnosis

can be established only by having samples of plasma

known to be specifically deficient in factor VIII and

factor XII. Failure of correction of the patient’s partial

thromboplastin time by plasma known to be deficient

in factor VIII establishes the diagnosis of hemophilia.

Likewise, failure of correction of the patient’s partial

thromboplastin time by plasma known to be deficient

in factor XII establishes the diagnosis of Hageman trait.

5. Factor XI deficiency may have a pattern similar to

that of factor VIII or factor IX deficiency. The correct

diagnosis can be further elucidated by the sex-linked

recessive transmission of factor VIII or factor IX

deficiency. Definitive diagnosis can be established

only by having available sample of plasma known

to be deficient in factors VIII, IX, and XI. Failure of

correction of the patient’s partial thromboplastin

time by plasma known to be deficient in factor XI

establishes the diagnosis of factor XI deficiency.

The two-stage prothrombin method is needed to

distinguish a true deficiency of prothrombin from the

pattern indicated for factor X deficiency.

A severe deficiency of fibrinogen will have a pattern

similar to that of factor V deficiency. A quantitative method

for fibrinogen is required to determine the fibrinogen

level.

For delving further into details of coagulation disorder

diagnosis, Tulip diagnostics provides kits for estimation

of—antiplasmin, antithrombin III, A2, antitrypsin, factor

II reagent, factor V reagent, factor VII reagent, factor VIII

reagent, factor VIII R:AG antiserum, factor IX, factor X

reagent, factor XIII, fibrinogen reagent,—macroglobulin,

PTT reagent, thrombin reagent, thrombin coagulase and

Staphylococcus clumping test.

LABORATORY DIAGNOSIS OF

COAGULATION DISORDERS

Some properties of the coagulation factors are given below:

1. Fibrinogen group: Factors, I, V, VIII, XIII.

• Thrombin interacts with them all

Prothrombin Partial thromboplastin time Presumptive diagnosis

Test plasma alone Test plasma Test plasma Test plasma Deficiency of

+BaSO4 plasma alone +BaSO4 plasma factor

Long Normal Long Normal V

Long Long Normal Normal VII

Normal Normal Long Normal VIII

Normal Normal Long Long IX

Long Long Long Long X

Clinical Hematology: Bleeding Disorders 305

FIG. 10.1: Hemostar

(Courtesy: Tulip Group of Companies)

• Activity lost in coagulation process (not present in

serum)

• Increase during inflammation, in pregnancy and

women on oral contraceptives

• Factors V and VII lose activity in stored plasma

• Liver parenchyma synthesis (except factor VIII).

2. Prothrombin group: Factors II, VII, IX and X.

• Activated form contains an active serine center

• Liver parenchymal cell synthesis

• All except prothrombin (II) are not consumed during

coagulation (present in serum)

• Dependent on vitamin K for synthesis

• Stable, well preserved in stored plasma.

3. Contact group: Factors XI, XII.

• Activated forms contain an active serine center

• Not dependent on vitamin K for synthesis

• Stable, well preserved in stored plasma.

Factor VIII is most important as far as coagulation

disorders are concerned. Its structure is as follows:

Abbreviations

VIII C = Part has coagulant activity.

VIII R: AG = Factor VIII Related Antigen, effects platelet

function also.