Predisposing factor | Prevalence in the western countries | Thrombotic risk as compared with general population (approximately) |
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1) Either quantitative deficiency of protein C (Type 1 deficiency) or qualitative impairment of its functional activity (Type 2 deficiency). Over 160 gene defects have been described. A single mutation (PC W380G) causes the majority of type 2 protein C deficiency cases in Finland. 2) Either quantitative deficiency of protein S or qualitative impairment of its functional activity. Over 200 gene defects have been described. 3) Either quantitative deficiency of antithrombin (Type 1 deficiency) or qualitative impairment of its functional activity (Type 2 deficiency). The thrombotic risk is related to the type and degree of the deficiency. Over 100 different gene defects are known. In Finland, type 2 deficiency is caused predominantly by a single mutation (Pro73Leu). | ||
Factor V Leiden (APC resistance, FV Leiden, FV R506Q, FV G1691A) heterozygous | 3-8% | Low-risk thrombophilia 3 × |
Factor V Leiden (APC resistance, FV Leiden, FV R506Q, FV G1691A) homozygous | <0.2% | High-risk thrombophilia >30 × |
G20210A point mutation in the prothrombin gene, heterozygous | 0.7-4% | Low-risk thrombophilia 3 × |
G20210A point mutation in the prothrombin gene, homozygous | <0.1% | High-risk thrombophilia >30 × |
Protein C deficiency1) | 0.2-0.5% | High-risk thrombophilia 10 × |
Protein S deficiency2) | 0.2-0.5% | High-risk thrombophilia 10 × |
Antithrombin deficiency 3) | 0.02-0.1% | High-risk thrombophilia Great variation between families, up to > 100 × |
Antiphospholipid antibody finding | Definition | Risk of thrombosis |
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* So-called Sydney criteria, ISTH 2006 | ||
Persistently weakly positive antiphospholipid, anticardiolipin or anti-beta-2-glycoprotein 1 antibodies | Weakly positive* = anticardiolipin and/or anti-beta-2-glycoprotein 1 antibodies positive result in at least two samples taken HASH(0x2f82cc8) 12 weeks apart, but low titre (laboratory-specific limit) | The diagnostic criteria for antiphospholipid syndrome are not met even if there are clinical manifestations. |
Persistently strongly positive lupus anticoagulant , anticardiolipin or anti-beta-2-glycoprotein 1 antibodies | Strongly positive* = lupus anticoagulant positive and/or high-titre anticardiolipin antibodies and/or high-titre anti-beta-2-glycoprotein 1 antibodies found in at least two samples taken HASH(0x2f82cc8) 12 weeks apart (laboratory-specific titre limit) | The diagnostic criteria for antiphospholipid syndrome are met only if clinical manifestations are also observed. |
Persistent triple positivity (the more strongly positive, the more significant the finding) | Strongly positive = all (lupus anticoagulant + anticardiolipin antibodies + anti-beta-2-glycoprotein 1 antibodies) persistently positive | The diagnostic criteria for antiphospholipid syndrome are met only if clinical manifestations are also observed. |
Antiphospholipid syndrome | Clinical manifestation (history of venous and/or arterial thrombosis and/or pregnancy-related complication, see Systemic Lupus Erythematosus (Sle)) plus the laboratory criteria for strongly positive antiphospholipid antibodies are met. | High risk (see deep vein thrombosis Deep Vein Thrombosis and SLE Systemic Lupus Erythematosus (Sle)) |
Catastrophic antiphospholipid syndrome | The criteria for antiphospholipid antibodies are met plus generalized microthrombosis, multiorgan failure and typically thrombocytopenia | Very high risk |
Type of thrombophilia | Tests (B = blood, P = plasma) |
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*If the screening test for thrombophilia is positive, testing should be followed up with a confirmatory test | |
Inherited | P antithrombin III |
B factor V gene, DNA test | |
P protein C | |
P protein S | |
B prothrombin gene, DNA test | |
P thrombin time | |
Acquired | P thromboplastin time |
P cardiolipin, IgG antibodies | |
P cardiolipin, IgM antibodies* | |
P lupus anticoagulant, dRVVT* | |
P lupus anticoagulant, PTT* | |
P beta-2-glycoprotein, IgG antibodies | |
P F-VIII |