Test Catalog

Test Id : FHEP2

Heparin Cofactor II

Useful For
Suggests clinical disorders or settings where the test may be helpful

Assessment of thrombotic risk associated with heparin cofactor II levels.

Method Name
A short description of the method used to perform the test


NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Heparin Cofactor II

Lists additional common names for a test, as an aid in searching

Dermatan Sulfate Cofactor


Heparin Cofactor A

Specimen Type
Describes the specimen type validated for testing

Plasma Na Cit

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Patient Preparation: Do not draw from an arm with a heparin lock or heparinized catheter.

Specimen Type: Citrated plasma

Collection Container/Tube: Light-blue top (citrate)

Specimen Volume: 2 mL

Collection Instructions: Draw blood in a light blue-top (Sodium citrate) tube(s). Spin down and send 2 mL citrated plasma frozen in a plastic vial.


Note: Separate specimens must be submitted when multiple tests are ordered.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

1 mL (Note: This volume does not allow for repeat testing.)

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Thawing** Cold reject; Warm reject
Other/Tissue/Swab Specimens other than Plasma; Anticoagulants other than Sodium citrate

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen 180 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Assessment of thrombotic risk associated with heparin cofactor II levels.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Heparin cofactor II is a glycoprotein that belongs to the serine protease inhibitor family. Heparin cofactor II, also known as heparin cofactor A or dermatan sulfate cofactor, has a molecular weight of approximately 65 kilodaltons and has a plasma concentration of 9 mg/dL. Heparin cofactor II is synthesized by the liver and has a plasma half-life of 60 hours. Heparin cofactor II specifically inhibits thrombin, in contrast to antithrombin, which inhibits thrombin, factor Xa, and other serine proteases. The inhibition of thrombin by heparin cofactor II is approximately 10 times slower than antithrombin-mediated inhibition and occurs through the formation of equimolar complexes between the reactive site of the inhibitor and the active site of thrombin. The antithrombotic activity of heparin cofactor II is greatly enhanced (over 1000-fold) in the presence of heparin and dermatan sulfate. The physiologic function of the molecule is unclear, but its role may be to serve as an antithrombotic agent in the presence of dermatan sulfate. Acquired deficiencies of heparin cofactor II are reported in patients with liver disease and disseminated intravascular coagulation. Conversely, increased levels of heparin cofactor II may be observed in individuals with renal disorders with proteinuria, during pregnancy, and with oral contraceptive usage. Inherited deficiency of heparin cofactor II has been reported in rare instances and is inherited as an autosomal dominant trait. A clear relationship between increased risk of thrombosis and heparin cofactor II deficiency has not been established since deficiency of heparin cofactor II is observed in both healthy individuals and those with thrombotic episodes. Limited studies have shown that heterozygosity for heparin cofactor II is not a likely risk for thrombosis without other concomitant risk factors. Other studies have reported thrombotic episodes in 36% of individuals with the deficiency.

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.


In healthy adults, heparin cofactor II reference range in plasma is 65% to 145%. Plasma levels of heparin cofactor II are approximately 50% of adult levels at birth and reach adult levels at six months of age.

Method Description
Describes how the test is performed and provides a method-specific reference

Patient plasma is incubated with excess thrombin in the presence of dermatan sulfate. Residual thrombin activity reacts with chromogenic substrate and the color intensity is inversely proportional to heparin cofactor II levels. Heparin levels up to 1 U/mL do not affect the heparin cofactor II assay.

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Esoterix Coagulation

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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 instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

Results of this test are for research purposes only per the assay manufacturer. The performance characteristics of this assay have not been established. The result should not be used as a diagnostic procedure without confirmation of the diagnosis by another medically established diagnostic product or procedure.

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 Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
FHEP2 Heparin Cofactor II 33987-9
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
FHEP2 Heparin Cofactor II 33987-9

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports