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Test Name:
Partial Thromboplastin Time, Activated, with Mixing Studies if Indicated
- SBMF No:
25339 - Performance Lab Name:
Hem-Coag - Test Mnemonic:
APTT W/MIX - ABN:
May be required – Medical Necessity - CPT Code:
85730
If indicated, add 85732 - LOINC Code:
14979-9 - Also Known As:
aPTT with Mixing Studies
Activated Partial Thromboplastin Time with Mixing Studies - Spec Type:
Platelet-poor plasma (PPP) - Spec Container:
Light blue top (3.2% buffered sodium citrate) tube - Pref Vol:
1.0 mL - Min Vol:
0.3 mL - Fasting:
No - Patient Prep:
Collect prior to initiation of heparin therapy
If patient receiving other anticoagulant therapy, document medication information - Spec Collect:
- Routine venipuncture
- • NOTE: Traumatic puncture invalidates sample for coagulation studies and necessitates recollection
• Observe proper collection order for coagulation tests; collect tubes for coagulation studies prior to collecting tubes containing clot activators, additives, or anticoagulants
• Fill light blue top tube to stated tube volume
• If coagulation study is only test ordered, collect 1.0 to 2.0 mL blood into tube for discard, then collect light blue top coagulation study tube(s)
• If multiple coagulation studies are requested, submit additional samples for each coagulation test
• Immediately after collection, gently invert tube to mix
- Spec Process:
- Separate plasma from cells immediately
- • Promptly centrifuge 15 minutes
• Carefully transfer plasma portion of sample to separate plastic tube using plastic pipette
• NOTE: Buffy coat layer of sample must be avoided
• Centrifuge transferred plasma sample again to produce platelet-poor plasma (PPP)
• Use second plastic pipette to carefully transfer PPP sample into plastic aliquot tubes
• Immediately freeze PPP samples
- Spec Store Transport:
Room temperature for whole blood in unopened tube and received by SBMF within 4 hours of collection
If greater than 4 hours, sample must be centrifuged and plasma must be frozen - Spec Stability:
4 hours room temperature (20-30°C) if whole blood maintained in unopened collection tube
Note: Refrigeration not recommended
2 weeks frozen (-20°C), if centrifuged and plasma transferred to separate tube – Do not use frost-free units that undergo repeated freeze/thaw cycles - Spec Reject:
Sample clotted or hemolyzed
Citrate tube underfilled or overfilled
Whole blood sample received more than 4 hours after collection (has not been centrifuged and frozen) - Methodology:
Photo-Optical Clot Detection - Use:
Used as a coagulation screening test for plasma-clotting factors, excluding factors VII and XIII, and is also used to determine the relative heparin level in heparinized patients - Clinical Significance:
The activated partial thromboplastin time test is a coagulation screening test for plasma-clotting factors, excluding factors VII and XIII, and is also used to determine the relative heparin level in heparinized patients. Heparin is an antithrombin agent. In the case of high dosage of heparin or continuing IV heparin drip, the aPTT will be prolonged and variable due to the antithrombic characteristic of the heparin present. - Reference Range:
23-34 seconds
Therapeutic range for heparin therapy: 50-80 seconds - Critical High Value:
90.0 seconds - Additional Test Info:
APTT Interpretation:
FACT DEF = Consistent with factor deficiency
INHIBIT = Consistent with an inhibitor
INDETERM = Indeterminate result - Day Run:
Sun-Sat (daily) - Time Run:
As received - Time Reported:
4 hours - Test Type:
COAGULATION
