Sorted By Test Name - Mayo Medical Laboratories

F_11
9067
F11IS
7803
FACTOR X INHIBITOR SCREEN
Negative
Clinical References: 1. Feinstein DI: Acquired inhibitors of blood coagulation. In Hematology:
Basic Principles and Practice. Edited by R Hoffman, EJ Benz Jr, SJ Shattil, et al. New York, NY,
Livingstone Press, 1991, pp 1380-1394 2. Kasper CK: Treatment of factor VIII inhibitors. Prog Hemost
Thromb 1989;9:57-86
Coagulation Factor XI Activity Assay, Plasma
Clinical Information: Factor XI is synthesized in the liver. Its biological half-life is 60 to 80 hours.
Factor XI is a component of intrinsic coagulation pathway which, when activated, activates factor IX to
IXa. Factor XI deficiency may cause prolonged partial thromboplastin time. Deficiency associated with
mild bleeding diathesis, but there is poor correlation between activity level and clinical bleeding. A
relatively high incidence of congenital deficiency occurs among Ashkenazi Jewish descent (hemophilia
C).
Useful For: Diagnosing deficiency of coagulation factor XI Investigation of prolonged activated partial
thromboplastin time
Interpretation: Acquired deficiency is associated with liver disease and rarely inhibitors.
Homozygotes: or =10%)
which may not reach adult levels for > or =180 days postnatal.*
*See Pediatric Hemostasis References in Coagulation Studies in Special Instructions.
Clinical References: 1. He R, Chen D, He S: Factor XI: hemostasis, thrombosis, and antithrombosis.
Thromb Res 2012 May;129(5):541-550 2. Martin-Salces M, Jimenez-Yuste V, Alvarez MT, et al:
Review: Factor XI deficiency: review and management in pregnant women. Clin Appl Thromb Hemost
2010;16 (2):209-213 3. Seligsohn U. Factor XI in haemostasis and thrombosis: past, present and future.
Thromb Haemost 2007;98(1):84-89 4. Santoro R, Prejano S, Iannaccaro P. Factor XI deficiency: a
description of 34 cases and literature review. Blood Coagul Fibrinolysis 2011Jul;22(5):431-435
Coagulation Factor XI Inhibitor Screen, Plasma
Clinical Information: Factor XI inhibitors typically arise in patients with congenital XI deficiency
(hemophilia C), after infusion of fresh frozen plasma or factor XI concentrates. Acquired factor XI
inhibitors rarely occur spontaneously.
Useful For: Detection and quantitation of inhibitor to coagulation factor XI
Interpretation: Normally, there is no inhibitor, ie, negative. If the screening assays indicate the
presence of an inhibitor, it will be quantitated and reported in Bethesda (or equivalent) units.
Reference Values:
FACTOR XI ACTIVITY ASSAY
Adults: 55-150%
Normal, full-term newborn infants or healthy premature infants may have decreased levels (> or =10%)
which may not reach adult levels for > or =180 days postnatal.*
*See Pediatric Hemostasis References in Coagulation Studies in Special Instructions.
FACTOR XI INHIBITOR SCREEN
Negative
Clinical References: 1. Feinstein DI: Acquired inhibitors of blood coagulation. In Hematology:
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