Test Overview

Test Methodology

Photo-optical clot determination with Factor VIII deficient substrate.

Test Usage

Detection of specific coagulation factor VIII deficiency

Reference Range*


* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Limitations

Test Details

Days Test Performed

Daily, 24 hours for UMHS inpatients, Emergency Department patients, and Veterans Hospital patients. Monday-Friday, 1 run per day for MLabs and outpatients.

Analytic Time

2 hours

Soft Order Code


MiChart Code

Factor 8 Assay



Coagulation Factor VIII Assay
Factor 8 Activity
Factor VIII Assay
Factor VIII:C Assay

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STAT Availability

STAT requests for this test will be performed on UMHS inpatients, Emergency Department patients, and Veterans Hospital patients.

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All specimens should be accompanied by a requisition.

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Specimen Requirements

Offsite Collection Instructions

Collect specimen in a blue top (citrate 3.2%) tube. Mix by inversion. Specimen should arrive at lab within 3 hours of collection; transport at room temperature. Alternatively, centrifuge, aliquot plasma into a polypropylene plastic vial, and freeze the specimen within 4 hours of collection. Transport frozen specimen on dry ice. Collection of the blood through lines that have been previously flushed with heparin should be avoided. If the blood must be drawn through a VAD (vascular access device), the line should be flushed with 5 mL of saline and the first 5 mL of blood or six dead space volumes of the VAD discarded.

Rejection Criteria

Specimens will be rejected if not properly filled, clotted, grossly hemolyzed, or contaminated with heparin.


Test is not indicated if the patient is receiving heparin or direct thrombin inhibitor anticoagulation therapy.


Blue Top Tube

Normal Volume

Full 2.7mL tube or 1mL plasma aliquot

Minimum Volume

Full 1.8mL tube or 1mL plasma aliquot

Additional Information

Decreased factor VIII may be seen in association with: hemophilia, von Willebrand's disease, hypothyroidism, and disseminated intravascular coagulopathy. Factor VIII is an acute phase reactant; levels rise during strenuous exercise, periods of acute stress, following surgery, and in most inflammatory conditions. Factor VIII levels are also increased in pregnancy, carcinoma, leukemia, liver or renal disease, diabetes, deep vein thrombosis, and myocardial infarction.

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Fee Codes

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