Test Catalog

Test ID: F_11    
Coagulation Factor XI Activity Assay, Plasma

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosing deficiency of coagulation factor XI


Investigation of prolonged activated partial thromboplastin time

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

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).

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

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 section in Coagulation Guidelines for Specimen Handling and Processing in Special Instructions.

Interpretation Provides information to assist in interpretation of the test results

Acquired deficiency is associated with liver disease and rarely inhibitors.


Patients that are homozygous: <20% activity


Patient that are heterozygous: 20% to 60% activity

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Decreased plasma levels of factor XI do not correlate well with bleeding risk.

Clinical Reference Recommendations for in-depth reading of a clinical nature

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

Special Instructions Library of PDFs including pertinent information and forms related to the test