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Test Code PTT Mx Partial Thromboplastin Time Mix

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.

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.

CPT Codes

85732 x2