Activated Protein C Resistance
(APCR) Results With and Without Rivaroxaban in Patients With and Without Heterozygous Factor V Leiden Heterozygous/ Heterozygous/ Wild Type/ Rivaroxaban No Rivaroxaban Rivaroxaban APCR, mean 1.75 (0.12) 1.64 (0.09) 2.63 (0.23) (SD), N = 60 Rivaroxaban 143 (95;45-349) Not applicable 147 (79;68-311) concentration, ng/mL, mean (SD; range) Normal APCR/No Rivaroxaban APCR, mean 2.49 (0.18) (SD), N = 60 Rivaroxaban Not applicable concentration, ng/mL, mean (SD; range) Table 2.
Association of primary antiphospholipid syndrome with inherited activated protein C resistance. J Rheumatol 1998;25:1232-4.
Acquired activated protein C resistance is associated with lupus anticoagulants and thrombotic events in pediatric patients with systemic lupus erythematosus.
Acquired activated protein C resistance is associated with the co-existence of anti-prothrombin antibodies and lupus antico agulant activity in patients with systemic lupus erythematosus.
Activated protein C resistance caused by Arg506G1n mutation in factor Va.
 Nonstandard abbreviations: aPL, anti-phospholipid; anti-CL/[beta]2-GPI, anti-cardiolipin/[beta]2-glycoprotein I; anti-PS/PT, anti-phosphatidylserine/prothrombin; LA, lupus anficoagulant; SLE, systemic lupus erythematosus; PE, pulmonary embolism; VTE, venous thromboembolism; APC, acfivated protein C; APC-R, activated protein C resistance; DVT, deep vein thrombosis; TBS, Tris-buffered saline; BSA, bovine serum albumin; APTT, activated partial thromboplastin time; OR, odds rafio; CI, confidence interval; and mAU, milliabsorbance unit(s).
Although factor V Leiden mutation is the cause of activated protein C resistance in most cases, we recommend that activated protein C resistance testing be done first, as it is a less expensive and more widely available test than the DNA-based factor V Leiden mutation test.
If testing for activated protein C resistance is possible and the result is positive, confirmatory testing for factor V Leiden is indicated.
CLINICAL TESTING FOR ACTIVATED PROTEIN C RESISTANCE AND FACTOR V LEIDEN
The Clot-Based Tests for Activated Protein C Resistance
The original test for activated protein C resistance that was offered for use in clinical laboratories was a partial thromboplastin time (PTT) performed in the presence and absence of exogenously supplied activated protein C.
The limitations in the originally devised assay for activated protein C resistance led to the development of a modified assay.