Elevated factor IX activity is associated with an increased odds ratio for both arterial and venous thrombotic events.

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.

Discard tubes are not necessary when drawing samples for specialized coagulation testing.

Discard tubes have traditionally been obtained when drawing samples for coagulation testing to avoid potential tissue factor activation of coagulation in the first tube that may lead to inaccurate results. Although discard tubes are no longer required for prothrombin time and partial thromboplastin time, the practice is still recommended for other coagulation studies due to lack of sufficient evidence that discard tubes are not needed. The objective of the present study was to determine whether the first citrate tube drawn can be used for special coagulation testing.

Effects of EDTA on routine and specialized coagulation testing and an easy method to distinguish EDTA-treated from citrated plasma samples.

Coagulation testing is performed with citrate-treated plasma. Samples submitted in other anticoagulants, such as EDTA, should not be tested. We aimed to evaluate the effects of EDTA on routine and specialized coagulation tests and to establish sodium tetraphenylborate testing as a quick and reliable method to identify EDTA-treated plasma samples.

Pediatric reference intervals for uncommon bleeding and thrombotic disorders.

This study provides pediatric reference intervals and median values for factors II, V, VII, X, fibrinogen, alpha-2-antiplasmin (AP), antithrombin (AT), plasminogen, protein C (PC), and protein S (PS) for children 7 to 17 years of age. All analytes exhibited at least some age dependence in late childhood and adolescence either when compared against adult values or when medians for children were regressed against age.