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Test Code PTT Mx Partial Thromboplastin Time Mix

Useful For

If a sample is received which has a prolonged screening test(s), (PT or PTT), and it is desired to determine whether the prolongation is the result of an anticoagulant or a factor deficiency, mixing tests should be performed. The patient sample is mixed 1:1 with commercial normal pooled plasma. The presence of 50% activity of any factor is sufficient to obtain a normal PT or PTT result. If the patient has a factor
deficiency, the normal plasma will supply enough of the missing factor to give a normal result. If the PT or PTT does not correct upon mixing, then the presence of
anticoagulant, factor inhibitors or lupus anticoagulant is possible.

Patient Preparation

No special patient preparation required

Special Collection Instructions

Properly filled 9:1 ratio (blood to anticoagulant); 3.2% NaCitrate tube

Collection Method

Venous Draw; properly filled 9:1 ratio (blood to anticoagulant)

Minimum Volume

0.5 ml of plasma from a properly filled 1.8 mL or 2.7 mL NaCitrate (light blue) tube

Container

Light Blue Sodium Citrate
 

Preferred Specimen

2.7mL Lt. Blue (3.2% NaCitrate)

Acceptable Specimens

1.8 mL Lt. Blue (3.2% NaCitrate) tube

Reference or Target Ranges

Normal:

 

 

UH 25.8 – 33.0 seconds
WH 26.7 – 34.3 seconds

 

 

Reportable Units

Seconds

Critical Value

>150 Seconds

Reasons for Rejection

Hemolysis Threshold N/A
Icterus Threshold N/A
Lipemia Threshold N/A
Interfering Subtances/Other Short draws, over draws, clotted, improperly labeled

Specimen Stability

Ambient Plasma – 4 hours – Specimens must be centrifuged within 1 hour of phlebotomy if the patient is theapeutically heparinized.
Refrigerated (4°C to 8°C) N/A
Frozen(-70°C to -20°C) 2 Weeks@ -20°C; 1 year @ -70°C

Performance Information

Days and Time Performed 24/7
Expected Turn Around Time Routine: within 4 hours of arrival to lab
Stat Availability No
Performing Bench Coagulation
Methodology/Method Description UH: Stago STAR
Electromagnetic mechanical clot detection system.

CPT Codes

85732 x2