Requirements
- Personal protective equipment
- Lab coat
- Protective Apron
- Lab-grade gloves
- Shoe covers
- Protective face shield or protective goggles
- Spill kit
- Workstation
- Clean & disinfected workstation
- Tube discarder box
- Sharps discarder
- Calibrated Pipettes
- Calibrated water-bath
- Coagulation calibrated electrical centrifuge
- Thermometer
- Optimally functioning digital stopwatch
- Labelling marker
- Light source (Bright lamp)
- PT result recording sheet
- Calculator
- Test related
- Multiple clean glass tubes
- Citrated Control Platelet Poor Plasma (C-PPP)
- Citrated Test/Patient's Platelet Poor Plasma (T-PPP)
- QC verified Thromboplastin Reagent
- QC Verified Calcium Chloride CaCl2 Reagent
Procedure
- Step 1
- Label a clean glass test tube as CaCl2
- Add >100 μL CaCl2 reagent in this tube
- Place this test tube in water-bath at 37 0C for >2 mins
- Step 2
- Label 4 clean glass test tubes as following:
- C1 → Citrated Control PPP
- C2 → Citrated Duplicate Control PPP
- T1 → Citrated Test PPP
- T2 → Citrated Duplicate Test PPP
- Step 3
- Add 100 μL Citrated Platelet Poor Plasma (PPP) into C1 labelled tube
- Incubate C1 labelled tube in water-bath at 370C for 02 mins
- Step 4
- Take out 100 μL APTT reagent (from commercial APTT reagent bottle at room temperature) and add it to C1 labelled tube (which has completed 2 mins incubation in water-bath in Step 3)
- Incubate C1 labelled tube for 3 more minutes in water-bath at 370C
- Step 5
- After completion of 3 mins incubation in step 4, take out 100 μL CaCl2 reagent from CaCl2 labelled tube (which is already in water-bath from step 1) and add it to C1 labelled tube
- Start the stopwatch
- Step 6
- From 25 seconds onwards remove the C1 labelled tube from water-bath to see for clot formation at regular intervals (every 2 seconds)
- Note the time when the clot has formed & stop the Stopwatch
- Step 7
- Repeat the procedure as per above steps in C2 labelled tube
- Take the average of the readings from C1 & C2 labelled tubes
- Step 8
- Now, repeat all the above mentioned steps in duplicate with Test PPP from the patient in T1 & T2 labelled tubes
- Record the average of the readings from T1 & T2 labelled tubes
Reporting of Results
- Results are reported as per following two formats:
- The mean (average) of the APTT readings run in duplicate in seconds
- APTT ratio between Citrated Test & Control PPP
- For APTT Value of Citrated Control PPP in Routine
- GMNAPTT is calculated as the mean of PT for 20 healthy individuals as under:
- 10 samples from healthy males
- 10 samples from healthy females
- No sample from those receiving any oral anticoagulant
- The mean (average) of the APTT readings run in duplicate in seconds
- APTT ratio between Citrated Test & Control PPP
- GMNAPTT is calculated as the mean of PT for 20 healthy individuals as under:
- 10 samples from healthy males
- 10 samples from healthy females
- No sample from those receiving any oral anticoagulant
Interpretation of Results
- Causes of Isolated APTT prolongation with normal PT (Click For Details)
- Factor VIII, IX, XI, XII, Prekallikrein or HMWK deficiency
- FVIII deficiency secondary to VWD
- Circulating anticoagulant, e.g., Lupus Anticoagulant
- Heparin or direct acting anticoagulant
- Mild factor II, V or X deficiency
- Factor VIII, IX, XI, XII, Prekallikrein or HMWK deficiency
- FVIII deficiency secondary to VWD
- Circulating anticoagulant, e.g., Lupus Anticoagulant
- Heparin or direct acting anticoagulant
- Mild factor II, V or X deficiency
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