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MIXING STUDY (PT/APTT)

Mnemonic

PT MX or PTT MX

Synonym

50/50 Mixing Studies - Activated Partial Thromboplastin Time [APTT] Mixing Study - Partial Thromboplastin Time [PTT] Mixing Study - Prothrombin Time [PT] Mixing Studies - 1:1 Mixing Study

Guidelines

Legacy Emanuel Laboratory provides testing for:
- STAT, ASAP, Timed, AM orders
- NO interpretation is provided.

Legacy Central Lab:
- Routine orders ONLY
- Interpretation provided.

Specimen Collection Requirements

Collect

Whole Blood light blue (3.2% Buffered Sodium Citrate) top tube

Handling

See Coagulation Specimen Collection Guidelines. Due to short stability, whole blood specimen tubes must reach the testing department within 4 hours, otherwise submit frozen plasma aliquots. NOTE: Frost-free refrigerator freezers are not acceptable for frozen sample storage. If proper storage is unavailable at the collection site, freeze/store aliquots on dry ice. Alternatively, send the patient to the nearest Legacy Hospital Outpatient Lab for sample collection/processing.

If submitting whole blood, transport at ambient temperature (15-25°C) in original unopened tube. If submitting frozen plasma aliquots, specimens must remain frozen (-20°C) during transport.

Preferred Volume

Four 2.7 mL whole blood or four 2.0 mL frozen plasma aliquot

Minimum Volume

Two 2.7 mL whole blood or two 2.0 mL frozen plasma aliquot

Transport

Whole Blood: Ambient (15-25°C) Plasma: Frozen (-20°C), aliquots must remain frozen during storage and transport

Rejection Criteria

Clotted samples, samples collected in containers other than 3.2% buffered sodium citrate, tubes filled less than 90%, samples from patients with a Hematocrit greater than 55%, hemolyzed samples due to ex-vivo causes (i.e., difficult draw, poor sample draw), whole blood samples that were frozen before processing

Stability

WHOLE BLOOD: Ambient: 4 hours PLASMA: Ambient: 4 hours; Frozen: (-20°C) 2 weeks, (-70°C) 6 months

Testing Information

Performed

Legacy Emanuel Labs 24/7
Legacy Central Laboratory Mon - Fri 0800-1630, excluding weekends and holidays

Reported

24-48 hours

Method

Clotting

Reference Values

Reference Values

See report.

CPT Codes

PT Mixing: 85610 and 85611 PTT Mixing: 85730 and 85732

Last Updated: Thursday, January 5, 2017 03:41:25 AM


Client Services: 503-413-1234