Partial Thromboplastin Time, Activated

Partial Thromboplastin Time, Activated is a topic covered in the Davis's Lab & Diagnostic Tests.

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Synonym/Acronym:
aPTT, APTT.

Rationale
To assist in assessing coagulation disorders and monitor the effectiveness of therapeutic interventions.

Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings
(Method: Clot detection) 25 to 35 sec. The activated partial thromboplastin time (aPTT) is slightly prolonged in infants and children and is slightly shortened in older adults. Reference ranges vary with respect to the equipment and reagents used to perform the assay. For the patient on anticoagulants, therapeutic levels of heparin are achieved by adjusting the dosage so the aPTT value is 1.5 to 2.5 times the normal.

Critical Findings and Potential Interventions

  • Adults and Children: Greater than 70 sec

Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.

Consideration may be given to verification of critical findings before action is taken. Policies vary among facilities and may include requesting immediate recollection and retesting by the laboratory or retesting using a rapid point-of-care testing instrument at the bedside, if available.

Important signs to note are prolonged bleeding from cuts or gums, hematoma at a puncture site, bruising easily, blood in the stool, persistent epistaxis, heavy or prolonged menstrual flow, and shock. Monitor vital signs, aPTT levels, unusual ecchymosis, occult blood, severe headache, unusual dizziness, and neurological changes until aPTT is within normal range.

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