Test ID: F_12
Coagulation Factor XII Activity Assay, Plasma
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Diagnosing deficiency of coagulation factor XII
Determining cause of prolonged activated partial thromboplastin time
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Activated Partial Thromboplastin Clot-Based Assay
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Factor XII - Off hours order 399
Factor XII Activity Assay
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
See Coagulation Studies in Special Instructions.
Specimen Type: Platelet-poor plasma
Collection Container/Tube: Light-blue top (citrate)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Spin down, remove plasma, and spin plasma again.
2. Freeze specimen immediately at < or =-40 degrees C, if possible.
Additional Information:
1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.
2. Patient must not be receiving Coumadin or heparin therapy.
3. Each coagulation assay requested should have its own vial.
4. If priority specimen, mark request form, give reason, and request a call-back.
5. Coagulation testing is highly complex, often requiring the performance of multiple assays and correlation with clinical information. For that reason we suggest ordering Coagulation Consultations.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | Mild OK; Gross reject |
| Icterus | Mild OK; Gross reject |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Plasma Na Cit | Frozen | 14 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Factor XII is synthesized in the liver. Its biological half-life is 40 to 50 hours. Factor XII is a component of the contact activation system and is involved in both intrinsic pathway and fibrinolytic system
Factor XII deficiency is often discovered when activated partial thromboplastin time is found to be unexpectedly long. The deficiency causes no known bleeding disorder.
An association between severe factor XII deficiency and thrombosis risk has been proposed, but not proven.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Adults: 55-180%
Normal, full-term newborn infants or healthy premature infants may have decreased levels (> or =15% to 20%) which may not reach adult levels for > or =180 days postnatal.*
*See Pediatric Hemostasis References in Coagulation Studies in Special Instructions.
Interpretation Provides information to assist in interpretation of the test results
Acquired deficiency is associated with liver disease, nephritic syndrome, and chronic granulocytic leukemia.
Congenital homozygous deficiency: 20%
Congenital heterozygous deficiency: 20% to 50%
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Deficiencies of other contact activator proteins (prekallikrein, high molecular weight kininogen) can also cause prolonged activated partial thromboplastin time but do not cause clinical bleeding.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
Renne T, Schmaier AH, Nickel KF, et al: In vivo roles of factor XII. Blood 2012 Nov 22;120(22):4296-4303
Method Description Describes how the test is performed and provides a method-specific reference
The factor XII assay is performed on the Beckman Coulter ACL TOP using the activated partial thromboplastin time (APTT) method and a factor deficient substrate. Patient plasma is combined and incubated with a factor XII deficient substrate (normal plasma depleted of factor XII by immunoadsorption) and an APTT reagent. After a specified incubation time, calcium is added to trigger the coagulation process in the mixture. At which time, the time to clot formation is measured optically at a wavelength of 671 nm.(Owen CA Jr, Bowie EJW, Thompson JH Jr: Diagnosis of Bleeding Disorders. Second edition. Boston, MA, Little, Brown and Company, 1975)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
85280
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| F_12 | Coag Factor XII Assay, P | 3232-6 |
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