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Updated: May 7, 2026

Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
Elevated factor IX activity is associated with an increased odds ratio for both arterial and venous thrombotic events
Nahla M Heikal1, Karla K Murphy, Ronda A Crist
1ARUP Laboratories, 500 Chipeta Way, Mail Stop 115-G04, Salt Lake City, UT 84108; kristi.smock@aruplab.com.
Objectives:
Elevations of factor IX (FIX) are thought to contribute to thrombotic risk, but this has not been well characterized. We retrospectively sought to determine whether elevated FIX levels are a risk factor for thrombosis in 81 adult subjects younger than 65 years (mean, 47 years) who were referred for evaluation of a hypercoagulable state.
Methods:
Patients were classified by arterial transient ischemic attack/stroke (TIA/stroke, n = 62) or venous thromboembolism (VTE, n = 19) events. FIX activity testing was performed on all 81 subjects and a reference group of 40 healthy individuals.
Results:
Thirteen (21%) of 62 subjects with TIA/stroke and 5 (26%) of 19 subjects with VTE had elevated FIX activity. Odds ratios for TIA/stroke and VTE in subjects with elevated FIX activity were 3.7 (95% confidence interval [CI], 0.76-17.65) and 6.8 (95% CI, 1.18-39.07), respectively.
Conclusions:
Our findings suggest an association between elevated FIX levels and both arterial and venous thrombotic events.
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