Partial Thromboplastin Time (PTT)
| Sunquest Code: | PTT | ||
| Epic Code: | LAB56 | Epic Name: | Partial Thromboplastin Time (PTT) |
| Synonyms: | APTT; Activated Partial Thromboplastin Time | ||
| Methodology: | Electromagnetic clot detection | ||
| Test Includes: | |||
| Turnaround Time: | Performed and reported 24 hours/day. | ||
| Associated Links: | Specimen Collection and Processing for Coagulation Specimens |
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Collection Instructions
| Specimen: | Blood |
| Optimal Volume: | 2.7 mL (in 3 mL tube) - filled to fill line on tube |
| Minimum\Peds Volume: | 1.8 mL (in 2 mL tube) - filled to fill line on tube |
| Container: | Blue Na Citrate, 3.2% - fill to fill line on tube |
| Collection Instructions: | If the patient's hematocrit is >55%, contact laboratory to obtain a special tube. If using a butterfly needle, a waste tube must be collected before the blue top. |
| After Care: | If the patient has a coagulation abnormality, apply direct pressure to the puncture site for 10 minutes; apply a pressure dressing. Instruct the patient to leave the bandage on for 12 hours. |
| Causes for Rejection: | Underfilled tubes, overfilled tubes, clotted specimens, specimens collected in 3.8% buffered citrate.
Grand Itasca: Whole blood specimen greater than 4 hours old or not processed appropriately within 1 hour of collection. All other Fairview sites: Specimen greater than 2 hours old or not processed appropriately within 1 hour of collection. |
Processing and Shipping
| Specimen Processing: | Send whole blood or platelet poor plasma. See Associated Link for additional processing instructions. |
| Shipping Instructions: | Whole blood specimens must be processed within 1 hour of collection and tested within 2 hours. If greater than 1 hour is required for transport, follow specimen processing instructions and ship frozen plasma on dry ice. |
| Test Performed at or Referral Lab | Coagulation (University of Minnesota Health Maple Grove Clinics, Fairview Range - FRMC, UMMC-East Bank, Oxboro Bloom, Fairview Lakes - FLMC, Fairview Ridges - FRH, Fairview Northland - FNMC, Fairview Southdale - FSH, UMMC/UMMCH-West Bank, M Health Clinic and Surgery Center, Grand Itasca GICH) |
Interpretive
| Critical Range: | Greater than 119 seconds
Grand Itasca (GICH): All ages - greater than or equal to 60.0 seconds |
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| Reference Range: |
Grand Itasca (GICH): 22-37 seconds (all ages)
PTT on premature infants are approximately 20% higher.
All other Fairview sites:
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| Therapeutic Range: |
All Fairview sites, excluding Grand Itasca (GICH).
The target aPTT range for heparin therapy is:
Target range for anticoagulation with direct thrombin inhibitors, e.g., lepirudin [Refludan, bicalirudin, argatroban] is approximately 1.5-2.5 times the baseline aPTT. |
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| Use: | Monitoring heparin therapy; evaluation of intrinsic coagulation system. Aid in screening for the following: classical hemophilia (A and B); Christmas disease; congenital deficiencies (factors 2, 5, 8, 9, 10, 11, and 12; Fitzgerald factor; vitamin K; prekallikrein; hypofibrinogenemia); disseminated intravascular coagulation; liver failure; circulatory anticoagulant. |
Click HERE to Report test errors or omissions.
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