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Test Code PTT APTT

Clinical System Name

APTT
 

Synonyms

APTT
Partial Thromboplastin Time
PTT
PTT Pharm

Description

APTT measures the integrity of the intrinsic and common pathways of coagulation. APTT prolongations are caused by either factor deficiencies (especially of factors VIII, IX, XI or XII), or the presence of inhibitors (most commonly; lupus anticoagulants, therapeutic anticoagulants such as heparin or direct thrombin inhibitors such as Argatroban).

Sample Requirements

Specimen: Whole Blood

Container(s): Lt Blue/Citrate

Preferred Vol: 1.8 mL

Minimum Vol: N

 

Note:  Preferred method of collection is venipuncture with vacuum fill.  Test results are affected by incorrect blood volume, note fill line on tube.  Use of a Vascular Access Device for the  collection of coag testing is not recommended.

If this method is used it requires a 5 mL waste volume; 3 mL for size 2 French catheter or smaller. Blood must be trasferred to the  Lt Blue/Citrate tube by use of a  blood transfer device to ensure proper fill. 

Specimen should be centrifuged within 1 hour of collection.

Processing Instructions

Reject due to: Clotted, Hemolyzed, Insufficient quantity, and  Improper collection.

Spin:N

Aliquot:N

Temp:RT

Storage location: Core 6 Freezer  ( -70 C).

 

Note: Deliver blood to Core Coag bench.  Coag Technologist will process. Specimen should be centrifuged within 1 hour of collection. Spin whole blood, remove plasma. Transfer upper 3/4 layer of plasma to plastic tube affixed with large computer label.

 

 

 

Off-site collection: Preferred method of collection is venipuncture with vacuum fill. Test results are affected by incorrect blood volume, note the fill line on the tube. Use of a Vascular Access Device for the collection of coag testing is not recommended. If this method is used it requires a 5 mL waste volume; 3 mL for size 2 French catheter or smaller. Blood must be transferred to the Lt Blue/Citrate tube by use of the blood transfer device.

Specimen should be centrifuged within 1 hour of collection. Double spin, transfer upper 3/4 layer of plasma to plastic tube affixed with large computer label. Freeze one aliquot of 1.0 mL plasma in plastic tube at -70C.

Ship frozen on dry ice.

.

Stability

Specimen Type Temperature Time
Citrated platelet-poor plasma Room temp N
  Refrigerated N
  Frozen   -20 C or -70 C 3 m

 

Availability

STAT Performed TAT
Y

Daily

1 h

 

Performing Laboratory

Seattle Children's Laboratory    

 

Department

Department:  Coagulation

Phone Number: 206 987-2578

 

 

 

Reference Range

Age Seconds
New Born - 3 months 25 - 40
3 Months and Older 25 - 35

 

There are no established reference ranges for premature newborns.

 

Methodology

Method:  Electromagnetic mechanical clot detection system by STA® - Compact Analyzer

Analytical Volume: 1 mL plasma

This is enough for a PT, PTT, TT, and Fibrinogen on the same sample.

 

Limitations: Method is affected by improper collection, processing and storage.

High hematocrit greater than or equal to 56% requires a citrate adjusted tube.

CPT Codes

85730

Critical Values

≥ 150 seconds.