Hypercoagulable States - Thrombophilia

Hypercoagulable states may be acquired or inherited. Hereditary thrombophilia is a genetically determined increased risk for thrombosis and thromboembolism.

Key Points

The widespread use of numerous anticoagulants for a variety of diseases, including the newest direct oral anticoagulant agents, has created clinical dilemmas for both anticoagulant monitoring and the interpretation of coagulation testing. Evaluations for thrombophilia may demonstrate interference once heparin and/or warfarin or one of the new direct agents is administered, making interpretation of results difficult. The table below details possible interferences with coagulation parameters based on the specific drug administered.

Anticoagulants and Possible Coagulation Test Interferences
Anticoagulant Unfractionated Heparin LMWH Warfarin Direct Thrombin Inhibitorsa Direct Factor Xa Inhibitorsb
Common coagulation assays

PT/INR

Prothrombin Time/International Normalized Ratio 0030224

No effectc

No effectc

Prolonged

No effect/
prolongedd

Prolongedd/
no effect

aPTT

Partial Thromboplastin Time 0030235

Prolonged

No effect/
prolonged

No effect/
prolonged

Prolongedd/
no effect

No effect/
prolongedd

D-dimer

D-Dimer 0030057

No effect

No effect

No effect

No effect

No effect

Fibrinogen

Fibrinogen 0030130

No effectc

No effectc

No effect

No effect/
underestimated

No effect

Fibrinogen antigen

Fibrinogen Antigen 0030135

No effect

No effect

No effect

No effect

No effect

Reptilase time

Reptilase Time with Reflex to Reptilase Time 1:1 Mix 0030295

No effect

No effect

No effect

No effect

No effect

Thrombin time

Thrombin Time with Reflex to Thrombin Time 1:1 Mix 0030260

Prolonged

No effect/
prolonged

No effect

Prolonged

No effect

Thrombotic risk assays

APC resistance

APC Resistance Profile 0030127

OR

APC Resistance Profile with Reflex to Factor V Leiden 0030192

No effectc

No effectc

No effecte

Possible false negative

Possible false negative

Antithrombin activity, IIa method

Antithrombin, Enzymatic (Activity) 0030010

No effectf

No effectf

No effectf

Overestimated

No effect

Antithrombin antigen

Antithrombin, Antigen 0030015

No effectf

No effectf

No effectf

No effect

No effect

Protein C activity, clot-based

Protein C, Functional Protein C, Functional 0030113

No effectc/
overestimate

No effectc/
overestimate

Decreased

Overestimated

Overestimated

Protein C antigen

Protein C, Total Antigen 0030111

No effect

No effect

Decreased

No effect

No effect

Protein S activity

Protein S, Functional 0030114

No effectc/
overestimate

No effectc/
overestimate

Decreased

Overestimated

Overestimated

Protein S free antigen

Protein S Free, Antigen 0098894

No effect

No effect

Decreased

No effect

No effect

Protein S total antigen

Protein S, Total Antigen 0030112

No effect

No effect

Decreased

No effect

No effect

Lupus anticoagulants

DRVVT

Preferred test – Lupus Anticoagulant Reflexive Panel 0030181

OR

Dilute Russell Viper Venom Time (dRVVT) with Reflex to dRVVT 1:1 Mix and Confirmation 0030461

No effectc/
prolonged

No effectc/
prolonged

No effect/
prolonged

No effect/
prolongedd

Prolonged/
no effect

DRVVT confirmatory ratio

Dilute Russell Viper Venom Time (dRVVT) with Reflex to dRVVT 1:1 Mix and Confirmation 0030461

No effectc/
false positive

No effectc/
false positive

No effect/
possible false positivee

Possible false positive

Possible false positive

Hexagonal phospholipid neutralization

Preferred test – Lupus Anticoagulant Reflexive Panel 0030181

OR

Hexagonal Phospholipid Neutralization 0030064

No effectc/
false positive

No effectc/
false positive

No effect/
possible false positivee

Possible false positive

Possible false positive

Platelet neutralization procedure

Preferred test – Lupus Anticoagulant Reflexive Panel 0030181

No effectc/
false positive

No effectc/
false positive

No effect/
possible false positived

Possible false positive

Possible false positive

Fibrinolytic assays

Alpha-2-antiplasmin

Alpha-2-Antiplasmin, Activity 0098727

No effect

No effect

No effect

No effect

No effect

Fibrin/fibrinogen degradation products

Fibrin/Fibrinogen Degradation Split Products, Plasma 2006491

No effect

No effect

No effect

No effect

No effect

Plasminogen activator inhibitor-1

Plasminogen Activator Inhibitor 1, Activity 0098781

No effect

No effect

No effect

No effect

No effect

Plasminogen activity

Plasminogen Activity 0030190

No effect

No effect

No effect

No effect

No effect

tPA antigen

Tissue Plasminogen Activator, Antigen 0099187

No effect

No effect

No effect

No effect

No effect

Soluble fibrin monomer

Soluble Fibrin Monomer 0030126

No effect

No effect

No effect

No effect

No effect

Other assays

ADAMTS-13

ADAMTS13 Activity 0030056

No effect

No effect

No effect

No effect

No effect

Factor assays, clot-basedh

Factor II, Activity (Prothrombin) 0030007

Factor V, Activity 0030075

Factor VII, Activity 0030080

Factor VIII, Activity 0030095

Factor VIII Activity with Reflex to Bethesda Quantitative, Factor VIII 0030026

Factor IX, Activity 0030100

Factor IX Activity with Reflex to Bethesda Quantitative, Factor IX 0030032

Factor X, Activity 0030105

Factor XI, Activity 0030110

Factor XII, Activity 0030115

Factor XIII Activity 2006182

Factor XIII, Qualitative, with Reflex to Factor XIII 1:1 Mix 2002819

No effect/
underestimateg

No effect/
underestimateg

No effect/
decreased vitamin K-dependent factors

Underestimated

Underestimated

von Willebrand factor antigen and activity

von Willebrand Factor Antigen 0030285

von Willebrand Factor Activity (Ristocetin Cofactor) 0030250

No effect

No effect

No effect

No effect

No effect

APC = activated protein C; aPTT = activated partial thromboplastin time; DRVVT = dilute Russell viper venom time; INR = international normalized ration; LMWH = low molecular weight heparin; PT = prothrombin time; tPA = tissue plasminogen activator

aArgatroban, bivalirudin (Angiomax), dabigatran (Pradaxa)

bRivaroxaban (Xarelto), apixaban (Eliquis), edoxaban (Savaysa)

cReagent contains heparin neutralizer; effect may be seen with supratherapeutic drug levels

fInterference in high concentrations of anticoagulant medication

eDrug does not interfere with assay, but presence may affect analyte

dDrug, concentration, and reagent dependent

gaPTT-based factor assays (factors 8, 9, 11, 12) are more likely to demonstrate assay interference and underestimation than PT-based factors assays (factors 2, 5, 7, 10). The effect is more pronounced with unfractionated heparin than with LMWH.

hPresence of unfractionated heparin, LMWH, direct thrombin inhibitors, and direct Xa inhibitors may produce inhibitory patterns and may prevent accurate quantitation (underestimation) of factor activity. May also interfere with and cause false-positive Bethesda assays (false-positive coagulation factor inhibitor). Chromogenic Factor XIII activity may also be falsely decreased in the presence of direct thrombin inhibitors.

Sources: Linkins, 2002; Molinaro, 2008; Genzen, 2005; Hillarp, 2010; Adcock, 2015; Dale, 2014; Tsutsumi, 2014

Diagnosis

Indications for Testing

  • New or recurrent venous thromboembolism (VTE) without obvious risk factors (see Differential Diagnosis)
    • Abnormalities may be identified in a significant number of patients; however, identification of an abnormality may not predict risk of recurrence or alter therapeutic plan
    • Use when the results will impact management of the patient or patient family members
    • Do not order testing for first deep vein thrombosis (DVT) in the setting of known etiology (Five Things Physicians and Patients Should Question, 2015; Society for Vascular Medicine)
    • Do not test during acute episode – results do not alter therapy and some results may be inaccurate
  • Any of the following situations (College of American Pathologists [CAP], 2002; Grody, American College of Medical Genetics and Genomics [ACMG], 2001)
    • Idiopathic thrombosis in patient ≤50 years
    • Recurrent thrombosis
    • Unusual sites of thrombosis in the absence of risk factors
    • First-degree relatives with thromboses
    • Thrombotic event during pregnancy or while taking oral contraceptives or hormone replacement therapy

Laboratory Testing

  • Based on family and patient history – nongenetic tests may be altered by anticoagulant therapy or acute phase reaction due to clot
  • Consider acquired disorders such as antiphospholipid syndrome
  • Children – very low risk for thrombophilia and should only have testing performed in consultation with hematologist (ACMG)
  • If testing pursued
    • Do not test for protein C, protein S, or antithrombin (AT) levels during an active clotting event to diagnose a hereditary deficiency because these tests are not analytically accurate during an active clotting event (Choosing Wisely: 20 Things Physicians and Patients Should Question, 2017; American Society for Clinical Pathology)
    • Consider the following combination (ACMG)
      • Activated protein C resistance (with or without reflex to factor V Leiden [FVL] mutation); factor V R2 A4070G mutation
      • Prothrombin mutation
      • AT activity
      • Protein C activity
      • Free protein S
    • Less common disorders – testing may be considered if results are uninformative and additional testing is considered necessary
  • The following tests are not recommended
    • Factor VIII activity – testing other factor activities such as factor VIII and factor IX is controversial and not currently recommended
    • Factor XIII (F13A1) V34L variant – presence of variant associated with decreased/reduced risk for DVT, myocardial infarction, and coronary artery disease in Whites
  • Before making a definitive diagnosis of an inherited thrombophilia, consider repeating abnormal functional or antigenic testing
    • False positives and false negatives may encourage inappropriate therapies or follow-up planning
    • Low results can be obtained due to patient condition/biologic variability, medications, and assay variability or interference
    • Normal ranges vary by age and gender and must be considered when interpreting results

Differential Diagnosis

  • Acquired thrombophilia is more common than inherited thrombophilia and should be considered when evaluating patients with thrombosis
    • Antiphospholipid antibodies/lupus anticoagulant
    • Malignancy
    • Long-distance travel
    • Trauma
    • Surgery
    • Immobilization
    • Presence of a central venous catheter
    • Pregnancy/postpartum
    • Therapy-related thrombophilia

Screening

Population testing is not recommended for unselected patients.

Background

Epidemiology

  • Adults
    • Incidence – 30-500/10,000 for all disorders
    • Ethnicity
      • Slightly higher among African Americans
      • Lower in Asian and Native Americans
      • Inherited Thrombophilic Disorders
        Disorder Prevalence in Normals (%) Frequency in Patients with VTE (%) Relative Risk of First Episode of DVT

        Factor V Leiden (heterozygous)

        0.05-4.8a

        18.8

        7

        Factor V Leiden (homozygous)

        0.02

        1.5

        80

        Factor V with R2 mutation

        0.06-0.12

        10.0

        7 (heterozygote)

        10 (compound heterozygote)

        Prothrombin G20210A allele

        0.06-2.7a

        7.1

        2.8

        Protein C deficiency

        0.2-0.4

        3.7

        6.5

        Protein S deficiency

        0.16-0.21

        2.3

        5.0

        Antithrombin deficiency

        0.02

        1.9

        20

        Dysfibrinogenemia

        <0.01

        0.8

        Unknown

        Hyperhomocysteinemiab

        5-7

        10

        2.95

        Elevated factor VIII level

        11

        25

        4.8

        Elevated factor IX level

        10

        20

        2.8

        Elevated factor XI level

        10

        19

        2.2

        Elevated lipoprotein (a) level

        7

        20

        3.2

        Elevated TAFI

        9

        14

        1.7

        aPercent lowest in Asian or African descent; highest in White descent

        b>18.5 µmol/L

        DVT, deep vein thrombosis; TAFI, thrombin-activatable fibrinolysis inhibitor; VTE, venous thromboembolism

        Source: Whitlatch, 2008

  • Pediatrics
    • Incidence – 0.05-14/100,000
    • Sex – M<F
    • Age
      • Peak in neonates and infants <1 year
      • Second peak in puberty

Etiologies

Most Common Thrombophilias

  • Factor V Leiden (FVL)
    • Genetics and pathophysiology
      • FVL mutation of the F5 gene is the most common inherited thrombophilia
        • Accounts for more than 90% of patients with activated protein C resistance (APC-R)
          • During normal hemostasis, APC limits clot formation by proteolytic inactivation of factors Va and VIIIa
          • FVL prevents inactivation of factor Va by APC at the normal rate, increasing the risk for thrombosis
        • Functional tests for APC-R are generally used to screen for FVL
          • DNA tests are used to confirm positive screening tests and to differentiate between heterozygotes and homozygotes
      • Incomplete autosomal dominant inheritance
        • Heterozygotes have a 5- to 10-fold increased risk
        • Homozygotes have a 50- to 100-fold increased risk
    • Clinical presentation
      • Venous thromboembolism (VTE) is the most common type of thrombotic event
        • Recurrent VTE (pulmonary embolism, deep vein thrombosis [DVT]) is uncommon in heterozygotes unless additional risk factors are present
        • Increased risk of recurrent VTE in homozygotes
      • Pregnancy complications – recurrent miscarriage in the second trimester
    • Additional risk factors
      • Presence of F5 R2 (A4070G) mutation with FVL increases risk of thrombotic event 10-fold
      • ≥1 genetic risk factor – concomitant prothrombin G20210A mutation of F2, protein C deficiency, homocysteinemia
      • Acquired thrombophilic disorders (eg, malignancy, hyperhomocysteinemia, high factor VIII levels)
      • Nongenetic factors such as pregnancy, oral contraceptives, hormone replacement therapy, selective estrogen-receptor modulators, travel, immobilization, central venous catheters, surgery, transplantation, and advanced age
  • Prothrombin G20210A
    • Genetics and pathophysiology
      • Prothrombin G20210A mutation of the F2 gene – second most common inherited thrombophilia
        • Results in elevated levels of plasma prothrombin leading to hypercoagulability (gain of function)
        • Detected using DNA tests – factor II (prothrombin) activity testing may not identify the disease and should not be used for diagnosis
      • Autosomal dominant inheritance
        • Variable penetrance – many patients who are either heterozygous or homozygous for G20210A do not experience VTE
        • Heterozygosity causes a 2- to 4-fold increase in thrombotic risk
        • Homozygosity is rare and increases thrombotic risk above that observed in G20210A heterozygotes
    • Clinical presentation
      • VTE
      • Pregnancy complications – preeclampsia, placental abruption
    • Additional risk factors
      • Combined heterozygosity for both prothrombin G20210A and FVL mutations leads to thrombophilia with earlier onset, higher rate of recurrence, and more severe thrombotic events than either mutation alone
      • Increased risk of thrombosis associated with oral contraceptive use and pregnancy

Less Common Thrombophilias

  • Increased clotting factors – elevated factor VIII (FVIII) levels are often found in patients with venous thrombosis, but routine testing is controversial
  • Protein C deficiency
    • Genetics and pathophysiology
      • Protein C is a vitamin K-dependent plasma anticoagulant activated to APC by thrombin-thrombomodulin, which then inactivates factors Va and VIIIa
      • Inherited protein C deficiency is uncommon – 2 forms
        • Type I – quantitative
        • Type II – qualitative
      • Autosomal dominant inheritance – highly variable phenotypic expression
      • Functional assays preferred over antigenic assays for diagnosis – protein C levels vary with age
      • Decreased levels in acute thrombotic states, disseminated intravascular coagulation (DIC), liver disease, malnutrition (vitamin K deficiency), and with warfarin therapy
      • Increased levels in diabetes, nephrotic syndrome, pregnancy, and with oral contraceptive use
        • Elevated FVIII levels may result in falsely decreased values for some functional assays
        • Heparin and direct thrombin inhibitors may result in falsely elevated values for some functional assays
    • Clinical presentation
      • Additional risk factors likely necessary to provoke thrombosis (eg, infection – varicella-zoster virus [VZV], meningococcal)
      • VTE in heterozygotes
      • Neonatal purpura fulminans (DIC) in homozygous infants – widespread thromboses with hemorrhagic skin necroses
      • Warfa​rin-induced skin necrosis is rarely seen
  • Protein S deficiency
    • Genetics and pathophysiology
      • Protein S is a vitamin K-dependent plasma anticoagulant that acts as a cofactor for activated protein C and exists in 2 forms
        • Free protein S
          • 40% of the total
          • Physiologically active
        • Bound protein S (attached to C4b-binding protein)
          • 60% of the total
          • No anticoagulant activity
      • Inherited protein S deficiency is uncommon
        • 3 forms
          • Type I – quantitative
          • Type II – qualitative
          • Type III (also called type IIa) – quantitative with normal levels of total protein S
        • Autosomal dominant inheritance
        • Antigenic tests for free protein S preferred for diagnosis – free protein S values are higher in males than in females
      • Decreased levels in acute thrombotic states, nephrotic syndrome, inflammatory syndromes (due to increased C4b-binding protein), DIC, liver disease, malnutrition (vitamin K deficiency), pregnancy, and with estrogen and warfarin therapy
        • Elevated FVIII levels and/or APC resistance may result in falsely decreased values in some functional assays
        • Increased levels in heparin and direct thrombin inhibitors for some functional assays
    • Clinical presentation
      • Additional risk factors likely necessary to provoke thrombosis
      • VTE most common; arterial thrombosis may occur
      • Neonatal purpura fulminans (DIC) in homozygous infants
      • Warfarin-induced skin necrosis (rare)
  • Hyperhomocysteinemia (acquired or inherited)
    • Acquired
      • Independent risk factor for thromboembolic events
      • Most patients with hyperhomocysteinemia have no genetic variants or polymorphisms
      • Result of defective homocysteine metabolism and may be the result of vitamin B6, B12, or folic acid deficiency
      • Thrombotic risk most closely associated with increased fasting plasma homocysteine levels regardless of underlying etiology – plasma homocysteine testing is recommended over DNA-based tests
    • Inherited
      • Homocysteine metabolism defects caused by MTHFR gene variants
        • Most common variants – c.665C>T (p.Ala222Val) (previously designated C677T) and c.1286A>C (p.Glu429la) (previously designated A1298C)
        • Homozygosity for the c.665C>T variant is a risk factor for hyperhomocysteinemia
      • Autosomal recessive inheritance
      • Elevated plasma homocysteine level may be associated with a mild increase in risk for VTE independent of MTHFR status, but meta-analyses have cast doubt on the association between moderate homocysteine elevation and increased risk for coronary heart disease and VTE (Hickey, 2013)
      • The American College of Medical Genetics recommends MTHFR genotyping not be ordered as part of routine workup for thrombophilia due to questionable clinical significance (Hickey, 2013)
      • Inherited hyperhomocysteinemia rare
        • Graphic of clotting cascade with an emphasis on intrinsic and extrinsic pathways in inherited thrombophilias.
  • Antithrombin deficiency
    • Genetics and pathophysiology
      • Antithrombin (AT) – plasma anticoagulant; inactivates thrombin, factor Xa, and other activated clotting factors
        • AT activity enhanced by heparin-like glycosaminoglycans on the endothelial surface and by pharmaceutical heparin
        • Synthesized in the liver
      • 2 forms of inherited antithrombin deficiency
        • Type I – quantitative
        • Type II – qualitative
      • Autosomal dominant inheritance
        • Functional assays preferred for diagnosis
        • Homozygous state is embryonic lethal
      • Decreased levels occur in acute thrombotic states, liver disease, DIC, nephrotic syndrome, and heparin therapy; mild decreases may be seen in pregnancy or with oral contraceptive use
      • Increased levels may occur with long-term warfarin therapy
    • Clinical presentation
      • VTE
      • Recurrent thrombosis may occur even in the absence of additional risk factors
      • Some deficient patients are resistant to heparin therapy
  • Impaired clot lysis (dysfibrinogenemia, abnormal fibrinolysis)​

Acquired Thrombophilic State

Antiphospholipid syndrome

ARUP Laboratory Tests

Panel to evaluate for inherited and acquired thrombophilias

Method

Chromogenic Assay/Electromagnetic Mechanical Clot Detection/Quantitative Enzymatic/Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Polymerase Chain Reaction/Fluorescence Monitoring/Microlatex Particle Mediated Immunoassay

Recommended test to detect activated protein C (APC) resistance and confirm presence of a factor V Leiden variant

APC resistance profile may be affected by supratherapeutic concentrations of heparin, direct thrombin inhibitors, extreme factor V deficiency, or lupus anticoagulants with markedly prolonged baseline clotting times

APC resistance due to a cause other than a factor V variant will not be detected

Reflex pattern: if APC resistance is normal, then no further testing will be added; if APC resistance is low, then factor V Leiden by polymerase chain reaction (PCR) will be added

Acceptable panel to screen for uncommon inherited thrombophilias

Panel includes partial thromboplastin time (PTT), free functional protein C, protein S antigen, antithrombin enzymatic activity

Acceptable panel to detect and subtype protein C and S deficiencies

Do not order if the individual has been on warfarin therapy in the previous 2-4 weeks

Panel includes functional protein C, total antigen protein C, protein S free antigen, total antigen protein S

Reflex pattern: if functional protein C is low, total antigen protein C will be added; if free protein S is low, total antigen protein S will be added

Detect and subtype protein S deficiency

Do not order if individual has been on warfarin therapy in the previous 2-4 weeks

Reflex pattern: if low free antigen protein S is detected, then total antigen protein S will be added

Acceptable screening panel for common inherited thrombophilias

Panel includes APC resistance profile, prothrombin G20210A mutation, activated partial thromboplastin time (aPTT), factor VIII (FVIII) activity, and homocysteine

Reflex pattern: if APC resistance is normal, then no further testing will be added; if APC resistance is abnormally low, then factor V Leiden by PCR will be added

Related Tests

Screen for alpha-2-antiplasmin deficiency

Not a first-line test for diagnosing inherited thrombotic or bleeding disorders

Reflexive panel to assist in diagnosis of thrombotic thrombocytopenic purpura (TTP) and in distinguishing between inherited and acquired forms of TTP

Assist in diagnosing congenital or inherited thrombotic thrombocytopenic purpura (TTP)

Assist in distinguishing between inherited and acquired forms of thrombotic thrombocytopenic purpura (TTP)

Recommended initial test for the identification of autoantibodies to ADAMTS13; more specific for acquired TTP than ADAMTS13 antibody test

If TTP is suspected but antibodies are not identified by inhibitor test, ADAMTS13 antibody testing is recommended

Assist in distinguishing between inherited and acquired forms of thrombotic thrombocytopenic purpura (TTP)

Not recommended as the initial test for identification of autoantibodies to ADAMTS13; ADAMTS13 antibody test is less specific for acquired TTP than the inhibitor test

Order when acquired TTP is suspected but antibodies are not identified by the ADAMTS13 inhibitor test

Not recommended as an initial test to detect antithrombin (AT) deficiency

Use to determine subtype in AT-deficient individuals

Recommended test to detect AT deficiency

Detect and subtype AT deficiency

Acceptable initial test to detect activated protein C (APC) resistance due to a factor V Leiden (FVL) variant

Preferred test is APC resistance profile with reflex to FVL; however, FVL (F5) R506Q variant is the preferred initial test for individuals with supratherapeutic concentrations of heparin, direct thrombin inhibitors, Factor Xa inhibitors, extreme factor V deficiency, or lupus anticoagulants with markedly prolonged baseline clotting times

Aid in diagnosing and following disseminated intravascular coagulation (DIC)

Preferred test is a lupus anticoagulant reflexive panel

Reflex pattern: if dilute Russell viper venom time (dRVVT) is elevated, then dRVVT 1:1 mix will be added; if the dRVVT 1:1 mix is elevated, then the dRVVT confirmation test will be added

Evaluate for possible factor II deficiency

For prothrombin variant testing (inherited thrombotic risk factor), order prothrombin (F2) c.*97G>A (G20210A) pathogenic variant

Evaluate possible factor V deficiency

For FVL testing, order APC resistance profile with reflex to FVL or FVL R506Q mutation

Detect FVL variant

Genetic test for the most common genetic cause of thrombophilia

F5 gene variants, other than p.Arg534Gln (R506Q), are not evaluated by this assay

Results of F5 genotyping can be accurately determined for individuals on oral anticoagulant and standard heparin therapy

Rare diagnostic errors may occur due to rare sequence variations

Not recommended for population screening and testing of asymptomatic minors for FVL; exceptions may include young female smokers who have experienced myocardial infarction or individuals <50 years with acute arterial thrombosis in the absence of other risk factors (see Test Fact Sheet for full list of contraindications for FVL testing)

Determine thrombotic risk in individuals known to be FVL heterozygotes

F5 variants other than R2 (A4070G) are not evaluated

Test is not for individuals who are known to be negative or homozygous for FVL

Evaluate possible factor VII deficiency

Diagnose hemophilia A, acquired factor VIII deficiency, or as part of a diagnostic workup for von Willebrand disease

Not recommended when screening for thrombophilia

Diagnose factor VIII deficiency, detect factor VIII inhibitors, and monitor factor VIII replacement therapy

Reflex pattern: if factor VIII activity is 20 percent or less, then Bethesda quantitative, factor VIII will be added

Assess genetic risk for thrombosis

Assessment of genetic susceptibility for pulmonary embolism and deep vein thrombosis (venous thromboembolism [VTE]), myocardial infarction (MI), or coronary artery disease (CAD) in White individuals with a personal or family history of thrombotic event

Risk-benefit assessment for preventive or therapeutic interventions for VTE, MI, or CAD in White individuals

Variants in the F13A1 or F13B genes, other than the V34L sequence variant, are not evaluated

Diagnostic errors can occur due to rare sequence variations

The protective effect of the V34L sequence variant has not been established for ethnicities other than Whites and may be altered by other genetic and nongenetic factors not assessed by this test

Diagnose factor IX deficiency (hemophilia B) and monitor factor IX replacement therapy

Diagnose factor IX deficiency, detect factor IX inhibitors, and monitor factor IX replacement therapy

Reflex pattern: if factor IX activity is <20%, then Bethesda quantitative, factor IX will be added

Evaluate possible factor X deficiency

Diagnose factor XI deficiency (hemophilia C)

Evaluate the cause of an isolated prolonged partial thromboplastin time (PTT) in a patient who is not currently bleeding

Preferred first-line test to diagnose inherited or acquired factor XIII (FXIII) deficiency

More specific than qualitative assays for FXIII

Appropriate for evaluation of individuals with a bleeding disorder who present with normal prothrombin time (PT), PTT, and platelet count test results

Monitor therapy in individuals being treated for FXIII deficiency

Confirm abnormalities identified in the qualitative FXIII assay (clot solubility test)

A low FXIII level does not distinguish deficiency from a low value due to FXIII autoantibodies

Most useful for acquired or severe FXIII deficiency testing

Abnormal results should be confirmed with quantitative testing

Distinguish between FXIII deficiency and a FXIII inhibitor

Reflex pattern: if clot lysis occurs in the initial testing, then FXIII 1:1 mix will be added where the test is repeated using a 1:1 mix of patient plasma and pooled normal plasma to distinguish between FXIII deficiency and a FXIII inhibitor

D-dimer is the preferred test for evaluating coagulopathies (eg, disseminated intravascular coagulation [DIC])

If fibrin degradation products (FDP) testing is being considered, this plasma test, rather than the serum test, is the recommended test

Determine if fibrinogen deficiency is a potential cause of bleeding

Follow-up test for decreased fibrinogen activity to determine if the decrease is due to insufficient fibrinogen or dysfunctional fibrinogen

Preferred test is a lupus anticoagulant reflexive panel 

Acceptable screening test for disorders of methionine metabolism (congenital hyperhomocysteinemia)

Not recommended for risk assessment of cardiovascular disease (CVD) or VTE

Use for unexplained prolonged PTT or for patients with a significant probability of having antiphospholipid syndrome (APS)

For APS, order with anticardiolipin (aCL) and anti-beta-2-glycoprotein 1 (anti-b2GP1) antibody IgG and IgM assays

Panel includes dilute Russell viper venom time (dRVVT); dRVVT 1:1 mix (performed if dRVVT >44 seconds); dRVVT confirmation test (performed if dRVVT 1:1 mix >44 seconds); PTT; thrombin time; reptilase time; PTT heparin neutralized; PTT 1:1 mix (performed if PTT >48 seconds); platelet neutralization procedure (performed if PTT 1:1 mix >48 seconds); hexagonal phospholipid neutralization

Reflex pattern: if PTT and dRVVT are normal, then no further testing is performed; if PTT is abnormal, thrombin time is added; if thrombin time is normal, PTT 1:1 mix is added; if thrombin time is abnormal, reptilase time and PTT heparin neutralization is added; if PTT heparin neutralization is abnormal, PTT 1:1 mix is added; if PTT 1:1 mix is abnormal, platelet neutralization procedure is added; if dRVVT is abnormal, dRVVT 1:1 mix is added; if dRVVT 1:1 mix is abnormal, dRVVT confirmation is added; if platelet neutralization procedure and dRVVT confirmation are normal or if one is normal and the other not done, hexagonal phospholipid neutralization is added

Determine genetic contribution to hyperhomocysteinemia for individuals with elevated plasma homocysteine

Not recommended for recurrent pregnancy loss, thrombophilia screening, neural tube defect risk assessment, or testing of family members of individuals with identified MTHFR variants

Only the 2 MTHFR gene variants (c.665C>T and c.1286A>C) will be targeted

Diagnostic errors can occur due to rare sequence variations

Initial test for suspected bleeding disorder

Detect elevated concentrations of plasminogen activator inhibitor 1 (PAI-1)

Low concentrations of PAI-1 may not be accurately quantified

Not a first-line test for diagnosing inherited thrombotic or bleeding disorders

Screen for plasminogen deficiency

Not a first-line test for diagnosing inherited thrombotic or bleeding disorders

Acceptable panel to detect protein C and S deficiencies

Preferred test for detecting protein S deficiency is protein S free antigen

Panel includes functional protein C and functional protein S

Do not order if the individual has been on warfarin therapy in the previous 2-4 weeks

Preferred tests for detection of protein C and S deficiencies are functional protein C and protein S free antigen

Panel includes total antigen protein C and total antigen protein S

Do not order if individual has been on warfarin therapy in the previous 2-4 weeks

Recommended test to detect protein C deficiency

Do not order if individual has been on warfarin in the previous 2-4 weeks

Acceptable test to detect and subtype protein C deficiency

Do not order if individual has been on warfarin therapy in the previous 2-4 weeks

Reflex pattern: if functional protein C is decreased, then protein C total antigen will be added

Not recommended for detecting protein C deficiency; preferred test is functional protein C

Use to subtype deficiency in known protein C-deficient individuals

Do not order if individual has been on warfarin therapy in the previous 2-4 weeks

Recommended test to detect protein S deficiency

Do not order if individual has been on warfarin therapy in the previous 2-4 weeks

Acceptable test for detecting protein S deficiency

Preferred test is protein S free antigen

Do not order if the individual has been on warfarin therapy in the previous 2-4 weeks

Not recommended for detecting protein S deficiency; preferred test is protein S free antigen

Subtype deficiency in known protein S-deficient individuals in combination with protein S free antigen or functional protein S

Do not order if individual has been on warfarin therapy in the previous 2-4 weeks

Detect prothrombin c.*97G>A (G20210A) pathogenic variant

Evaluate for increased genetic risk of VTE in a variety of populations

Diagnostic errors can occur due to rare sequence variations

F2 gene variants, other than c.*97G>A (G20210A), will not be detected

Initial test for evaluating bleeding disorders and monitoring oral anticoagulation therapy (warfarin/Coumadin)

Assist in diagnosing dysfibrinogenemia or abnormalities with fibrin polymerization

Not recommended; order D-dimer test instead

Acceptable panel to detect 2 most common inherited thrombophilias (prothrombin related and FVL related)

Assist in diagnosing dysfibrinogenemia or abnormalities with fibrin polymerization

Screen samples for the presence of heparin or direct thrombin inhibitors

Determine quantity of tissue plasminogen (tPA) in plasma

May be helpful in detecting disorders of the fibrinolytic system

Not a first-line test for diagnosing inherited thrombotic or bleeding disorders

Order in conjunction with von Willebrand factor activity (ristocetin cofactor) and factor VIII activity as part of initial workup of suspected von Willebrand disease

Order in conjunction with von Willebrand factor antigen and factor VIII activity as part of initial workup of suspected von Willebrand disease

Evaluate prolonged clotting times such as PT and/or PTT when cause is unknown

Most useful for the workup of patients with unexpected prolonged clotting times

Condition-specific testing is recommended if the cause for the prolonged clotting time is known

Panel includes factor II activity; Bethesda quantitative, factor VIII and factor IX; D-dimer; factor V activity; lupus anticoagulant interpretation; factor VII activity; hexagonal phospholipid neutral reflex; PTT-D heparin neutralized; factor VIII activity; factor IX activity; factor X activity; factor XI activity; factor XII activity; soluble fibrin monomer; fibrinogen; platelet neutralization; dRVVT confirmation; PTT-LA screen; prothrombin time; von Willebrand factor activity; thrombin time; von Willebrand factor antigen; reptilase time; PTT-D 1:1 mix; dRVVT screen; dRVVT 1:1 mix; PT, inhibitor screen, 1:1: mix; prolonged clot time reflex panel interpretation

Medical Experts

Contributor
Contributor

Mao

Rong Mao, MD, FACMG
Professor of Clinical Pathology, University of Utah
Section Chief, Molecular Genetics and Genomics, ARUP Laboratories
Contributor
Contributor

Smock

Kristi J. Smock, MD
Professor of Clinical Pathology, University of Utah
Medical Director, Hemostasis/Thrombosis, ARUP Laboratories

References

Additional Resources
Resources from the ARUP Institute for Clinical and Experimental Pathology®