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Lab Dept:
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Coagulation
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Test Name:
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PTT, CIRCUIT
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General Information
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Lab Order Codes:
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PTTC
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Synonyms:
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APTT – circuit; Partial Thromboplastin Time – circuit; Activated PTT – circuit
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CPT Codes:
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85730 – Thromboplastin time, partial (PTT); plasma or whole blood
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Test Includes:
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PTT Circuit reported in seconds.
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Logistics
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Test Indications:
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Useful in monitoring/adjusting the amount of heparin being used in the external system during hemofiltration and extra corporeal membrane oxygenation (ECMO).
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Lab Testing Sections:
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Coagulation
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Phone Numbers:
Minneapolis:
Saint Paul:
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612-813-6280
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651-220-6550
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Test Availability:
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Daily, 24 hours
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Turnaround Time:
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2 hours
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Special Instructions:
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Patient’s with hematocrit levels >55% must have a special tube made to adjust for the hematocrit; contact the laboratory for special tube.
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Specimen
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Specimen Type:
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Whole blood
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Container:
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Light Blue top tube (Buffered Na Citrate 3.2%)
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Draw Volume:
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1.8 mL or 2.7 mL blood (in appropriate sized tube)
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Processed Volume:
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1 mL (Minimum: 0.5 mL) plasma
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Collection:
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● Mix thoroughly by gentle inversion.
● Deliver immediately to the laboratory. Indicate when specimen is drawn from a line or a heparin lock.
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Special Processing:
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Lab staff: Centrifuge in Stat Spin for 5 minutes or 10 minutes at 3000 rpm at room temperature. For primary tube testing, leave plasma on cells OR remove plasma and place in a 4 mL plastic cup; allow for 100 mL of deadspace.
Test within:
● Two (2) hours when stored 22 to 26°C.
● Four (4) hours when stored 2 to 4°C.
● Two (2) weeks when stored -20°C.● Six (6) months when stored -70°C (rapidly frozen).
● Plasma must be frozen if testing cannot be completed within four (4) hours.
● Frozen plasmas are thawed at 37°C for three (3) minutes, test immediately.
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Patient Preparation:
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None
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Sample Rejection:
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Improper tube; clotted sample; underfilled tube, mislabeled or unlabeled specimens
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Interpretive
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Reference Range:
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Approximately 1 – 1½ times the patient’s peripheral PTT value.
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Critical Values:
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N/A
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Limitations:
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N/A
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Methodology:
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Micronized silica
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References:
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Harmening DH (1997) Clinical Hematology and Fundamentals of Hemostasis
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Updates:
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7/19/2006: Removed statement, "Do not transport by pneumatic tube".
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