HAEMOSTASIS & HAEMOGLOBINOPATHY LABORATORY

The haemostasis & haemoglobinopathy laboratory has a vital role in the diagnosis and management of patients with hereditary and acquired bleeding and thrombotic disorders. It has also a vital role in the monitoring of patients under anticoagulant therapies. It provides a comprehensive service for the diagnosis and monitoring of patients with haematological disorders and haemoglobiopathies such as thalasaemia and sickle cell disease.

SAMPLE REQUIREMENT

Haemostasis tests are extremely sensitive to methods of collection and preservation. Therefore it is important to follow the instructions of blood collection and processing so we insure accurate test results.

Comments

Sample Age

3.2% Sodium citrated sample

(blue top)

TEST

*Centrifuge tubes at 3000g at 4°C for 15 minutes

*Samples should be transported in a closed ice box.

Not less than 4 hours from blood collection

1 tube of 4.5ml or 2.7 ml as whole blood or

1ml plasma into 5ml plastic tube

All Routine coagulation screening test

(APTT,PT,FIB ,TT & D-Dimer)

*Centrifuge tubes at 3000g at 4°C for 15 minutes and aliquot plasma.

*Samples should be transported in a closed ice box.

Not less than 4 hours from blood collection

1-2 tubes of 4.5ml or 2.7ml  or 4ml plasma into 5ml plastic tube

 

Multicoagulation*

Factors screen. 

*Anti-Xa heparin assay

*Factor VIII inhibitor screen

*Centrifuge tubes at 3000g at 25°C for 15 minutes filter and aliquot plasma.

*Samples should be transported in a closed ice box.

Not less than 4 hours from blood collection

2 tubes of 4.5ml or 2.7ml  as whole blood or

4ml plasma into 5ml plastic tube

  

Lupus anticoagulant

*Double Centrifuge tubes at 3000g at 25°C for 15 minutes and aliquot plasma.

*Samples should be transported in a closed ice box.

Not less than 4 hours from blood collection

4 tubes of 4.5ml or 2.7ml  as whole blood or

10ml plasma into 4 plastic tubes.

Thrombophilia assay &

Fibrinolysis assay.

*Double Centrifuge tubes at 3000g at 4°C for 15 minutes and aliquot plasma.

*Samples should be transported in a closed ice box.

Not less than 4 hours from blood collection

2 tubes of 4.5ml or 2.7ml  as whole blood or

4ml plasma into 5ml plastic tube

Von willebrand factor assay

Appointment to be schedule by the haemostasis laboratory.

 

See comments

NA

Platelet aggregation & bleeding Time

Appointment to be schedule by the haemostasis laboratory. Or Double Centrifuge tubes at 3000g at 25°C for 15 minutes and aliquot plasma.

Not less than 4 hours from blood collection

1 tube of 4.5ml whole blood

 

Heparin induced

thrombocytopenia

UNACCEPTABLE SAMPLE

Samples that are incorrectly collected, labeled, processed or transported will be rejected because this will lead to inaccurate results. The haemostasis and haemoglobinopathy laboratory will notify the area, by telephone or by fax.

REQUEST FOR TESTING

Testing is requested via the trackcare system used in the SQUH or hemostasis laboratory form (if samples sent from outside the SQUH). The electronic request or the ordinary form must have the following information to avoid delay or rejected in testing:
   - Patient identification (including patient`s name, hospital number & date of birth & all these must match information on sample).
   -Physician ordering test.
   -Date & time of request and sample collection.
   -Status of the sample, for example if frozen, filtered or double Centrifuged plasma is submitted.  
    -Name of the area (like wards or physician) or the hospital where the report should be sent.
  -The form must include a contact and phone number for someone who can answer questions concerning the order.

LABELING SAMPLES

All samples must be properly labeled and information must agree with the patient identification on the request form.

TRANSPORTING SAMPLES

All samples must be sent in a sealed bag marked with a biohazard sticker to comply with ISO9000 safety standard to haematology laboratory receiving area or to:
Sultan Qaboos university Hospital
Haematology Department
Haemostasis and Hemoglobiopathy Laboratory.
Tel. No:  +968-24141736        

Fax. No: +968-24144887

TEST RESULTS

The normal test results are usually authorized via the trackcare system used in the SQUH by the senior or chief in the haemostasis laboratory, the abnormal test results usually sent to the haematologist.

NORMAL RANGES

Units

Range

Sex, age & comments

Test

seconds

*9.7-11.4

*(To be established with every new PT reagents)

Adults

PT

Children

seconds

27 – 39*

*(To be established with every new APTT reagents)

Adults

APTT

children

g/L

1.8 – 4.9

Adults

Fibrinogen (Clauss)

seconds

11.9 – 19.6

Adults

Thrombin time

seconds

25 – 37

Adults

LA screen (APTT)

Seconds

31- 44

Adults

LA screen (DRVVT)

Seconds

28 - 34

Adults

LA confirmatory

(Drvvt)

IU/ml

0.500 – 1.580

Adults

VW Factor Antigen

IU/ml

0.500 – 4.000

Adults

Collagen binding assay (CBA)

IU/ml

0.400 – 1.500

Adults

VW Ristocetin cofactor

Minutes

2.3 – 9.5

Bleeding time

IU/ml

Adults

Protein C Functional 

0.720 – 1.540

Chromogenic assay

0.800 – 1.810

Clotting assay

IU/ml

0.700 – 1.400

Protein C Antigenic 

0.75 – 1.43

Adults

Protein C Global

4.2 – 6.2

Adults

Activated protein C Resistance (APCR)

Iu/ml

0.520 – 1.180

Adults

Protein S Functional

Iu/ml

0.620 – 1.300

Adults

Total protein S antigenic

Iu/ml

0.620 – 1.300

Adults

Free protein S antigenic

Iu/ml

0.830 – 1.180

Adults

Anti-thrombin funct. (IIa inhibition 180 sec)

Iu/ml

0.880 – 1.220

Adults

Anti-thrombin funct. (IIa inhibition 20 sec)

Iu/ml

0.800 – 1.400

Adults

Anti-thrombin antigenic

mol/L

5.0 – 15.0

Adults

homocysteine

ng/ml

1.0 – 12.0

Adults

Tissue plasminogen activator

ng/ml

4.0 – 43.0

Adults

Plasminogen activator inhibitor-1

Iu//ml

0.730 – 1.270

Adults

Plasminogen

Iu//ml

0.890 – 1.120

Adults

Alpha 2 antiplasmin

Iu//ml

0.600 – 1.160

Adults

Factor II:C assay

Iu//ml

0.550 – 1.270

Adults

Factor V:C assay

Iu//ml

0.470 – 1.270

Adults

Factor VII:C assay

Iu//ml

0.495 – 1.382

Adults

Factor VIII:C assay

Iu//ml

0.360 – 1.360

Adults

Factor IX:C assay

Iu//ml

0.380 – 1.180

Adults

Factor X:C assay

Iu//ml

0.490 – 1.340

Adults

Factor XI:C assay

Iu//ml

0.390 – 1.150

Adults

Factor XII:C assay

Iu//ml

Adults

Anti- factor Xa

Bethesda units/ml

0.00 – 0.75

Adults

Inhibitor assay (Bethesda)

mg/L FEU

0.19 – O.67

Adults

*(Cut-off point for DVT and/or PE = 0.5 mg/l)

D-Dimer assay

HAEMOSTASIS (COAGULATION) TESTS

Haemostasis (coagulation) services:  
In this laboratory we perform the following:

Routine Screening tests:

    1-Prothrombin Time
   
    2- Activated Partial Thromboplastin Time

    3- Fibrinogen activity (Clauss technique)

    4- Thrombin Time

    5- D-Dimer assay

Special Haemostasis (Coagulation) assays:

    1- Factors activity assays 
  
    2- Lupus anticoagulant assay     

    3- Thrombophilia assay  

    4- Vonwillibrand assay

    5- Factor VIII inhibitor screen (Bethesda assay)

    6- Anti-Xa heparin assay

    7- Homocystein assay

    8- Platelet Function (Platelet Aggregation Test & Bleeding Time)

    9- Heparin induced thrombocytopenia test (HITS).

   10- Fibrinolysis assay.



The Prothrombin time (PT) 
The Prothrombin time is a kinetic screening test. The PT assesses the extrinsic pathway of coagulation cascade that includes factors VII, X, V, Prothrombin and fibrinogen. The prolongation of the PT can be due to factor deficiency or factor inhibitor. The PT is more sensitive for liver disease or the presence of oral anticoagulant like warfarin. 

Activated Partial Thromboplastin time test (APTT)
The activated partial thromboplastin time test is a kinetic screening test that measures the recalcification time of plasma after incubation. The APTT assesses the coagulation factors of the intrinsic pathway that includes factors XII, XI, IX, VIII, V.X, II & fibrinogen. Prolongation of the APTT can be due to factor deficiency or factor inhibitor. APTT is more sensitive to the presences of heparin or lupus like- inhibitor.

Fibrinogen activity (Clauses technique)  
The Clauss thrombin-fibrinogen clotting reaction is determined in the presence of excess thrombin. The diluted plasma is mixed with an excess of thrombin and the coagulation time is determined. The clotting time obtained is considered proportional to the fibrin concentration. Decreased levels of fibrinogen are found in acquired hypo- or afibrinogenemia, DIC, liver disease or congenital hypofibrinogenemia. Since fibrinogen is an acute phase reactant, elevated levels are associated with stress or inflammation.

Thrombin Time (TT).
A low concentration of thrombin is added to plasma and the rate of reaction for the conversion of fibrinogen to fibrin is measured in seconds. It is used for the monitoring the inhibiting effects of heparin therapy on coagulation, as well as the fibrinolytic effects of streptokinase treatment.

D-Dimer assay:
D-Dimer test is used for the determination of cross-linked fibrin decomposition products in human plasma & in the diagnosis of thromboembolic events. Elevated concentrations of D-Dimer are indicative of the presence of a clot and have been reported in DVT, PE, liver disease & DIC.

 

Factor activity assays.
The coagulation factor assays are functional measurements of the individual clotting proteins which are performed using the appropriate PT & APTT assay for clot detection. The patient`s plasma is diluted with a plasma deficient in a single factor but with normal amounts of all other clotting factors. This will correct all factor deficiencies in the patient`s plasma except for the factor being tested.
Intrinsic coagulation factors are
 FVIII, FIX, FXI & FXII. 
Extrinsic and common coagulation factors are
 FVII, FII, FV & FX.


Lupus anticoagulant assay.
Lupus anticoagulants (LA) are nonspecific antibodies that extend the clotting of phospholipid-dependent clotting assays such as APTT.LA are usually associated with venous thrombosis ,SLE, pulmonary embolism, arterial thrombosis, and recurrent fetal loss. Due to the heterogeneity of LA antibodies, no single assay will identify all cases. The lupus anticoagulant panel used in the SQUH haemostasis laboratory consists of APTT-LA, mixing studies; DRVVT, DRVVT mix and DRVVT confirm test and hexagonal phospholipid assay.

Thrombophilia assay
The THROMBOPHILIA PANEL is designed to evaluate those proteins which have been clearly identified as inherited or acquired thrombotic disorders and include:
 * Protein C Functional (clotting assay)
 * Protein C Functional (Chromogenic assay)
 * Protein C Antigen ELISA-(if required)
 * Protein S Functional (clotting assay)
 * Protein S Antigen (%free) ELISA - (if required)
 * Protein S Antigen (%Total) ELISA - (if required)
 * Antithrombin III activity.
* Antithrobin III Antigen ELISA (If required) 
* APCR\ ProC Global.
* FVIII: C Levels.
* Homocystein levels.
* PNH Workup.