The document describes the procedure for performing an activated partial thromboplastin time (APTT) test using citrated plasma. The test involves incubating plasma with brain extract, kaolin, and calcium chloride before measuring the clotting time. Prolonged APTT results indicate deficiencies in the intrinsic coagulation pathway, such as issues with factors VIII, IX, XI, or XIII; liver disease; vitamin K deficiency; or disseminated intravascular coagulation.

2.  Specimen:-
Citrated plasma
 Principle:-
Partial thromboplastin (brain extract in
chloroform) is incubated with Kaolin (factor
XII contact factor activator). The clotting
time of plasma is determined after the
addition of calcium ions.

3.  Water bath (37°C)
 Test tubes
 Stop-watch
 Partial thromboplastin (brain extract in
chloroform)
 Calcium chloride (0.025 mol/L)
 Kaolin reagent: 2.0 gm/dl in normal saline
 Normal plasma (control)

4. 1. Pipette 0.1 ml of brain extract, 0.1 ml of
kaolin reagent and 0.1 ml of plasma in a
test tube.
2. Incubate at 37°C for one minute.
3. Add 0.1 ml of calcium chloride and start
the stop watch.
4. After 20 seconds, observe the formation of
the clot by tilting the test tube. As soon as
the clot forms, note the time.

5. 5. Repeat the procedure by using a normal
control plasma.
Normal range:-
30-40 seconds

6. Prolonged APTT is found in:-
1. Administration of Heparin
2. Liver disease
3. Vitamin K dificiency
4. Kidney disease
5. Patients suffering from Haemophilia A,
Haemophilia B.
6. DIC (Disseminated intravascular
coagulation)
7. Congenital deficiency of factors VIII, IX, XI
and XIII.

7.  Faulty collection of blood.
 Excess anticoagulant or insufficient
anticoagulant.
 Reagent not good.
 Glass tubes are not clean.
 Incorrect temperature of water bath. If
temperature is increased, factors may be
destroyed.