Abstract :
Introduction: APCR is a hemostatic disorder characterized by increased risk of deep vein thrombosis and
pulmonary embolism. Factor V Leiden mutation accounts for 95% of APCR cases & the remainder are due
to acquired causes like patients on vitamin k antagonist therapy, direct oral acting anticoagulants, Lupus
anticoagulant & oral contraceptive pills. T he main objective of this study is to compare the sensitivity of
APTT based APCR test vs Modified APTT with pre -dilution in F actor V-deficient plasma for diagnosis
of Factor V leiden mutation & to formulate a systematic diagnostic algorithm for interpretation of APCR
tests.
Materials and Methods: The Coagulometer used for APCR test is Sysmex CS-5100. APTT reagent used
is Pathrombin SL supplied by seimens. All data were expressed as Mean SD. Statistical analysis was
done using unpaired students t test & a P value
Results: A total of 150 cases of APCR (100 cases of factor V Leiden mutation confirmed by PCR &
50 non carrier /acquired cases) were studied retrospectively. Sensitivity of screening APTT base d APCR
for detection of factor V Leiden mutation is 78% & for non carrier state it is 82%. Sensitivity of modified
APTT with pre- dilution in FV-deficient plasmafor detection of factor V Leiden mutation is 93% & for
noncarrier state (acquired) is 34%.
Conclusion: Screening APTT test is increased in Activated protein C resistance due to factor V Leiden
mutation as well as acquired causes like patients on direct acting oral anticoagulants, warfarin, lupus
anticoagulants and oral contraceptive pills which are independent risk factors of venous thrombosis.
Modified APTT with predilution in FV-deficient plasma (1:4) is more sensitive than Screening APTT based
APCR test in diagnosis of Factor VLeiden mutation&this test can distinguish homozygous&heterozygous
states from normal individuals.
Keyword :
APTT, Activated Protein C resistance factor V Leiden mutation LAC