Factor XIII, Qualitative, with Reflex to Factor XIII 1:1 Mix
Ordering Recommendation
Most useful for acquired or severe FXIII deficiency testing. Abnormal results should be confirmed with quantitative testing (Factor XIII Activity 2006182)
Submit With Order
Qualitative Solubility
2-3 days
New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Lt. blue (sodium citrate). Refer to Specimen Handling at aruplab.com for hemostasis/thrombosis specimen handling guidelines.  
Specimen Preparation
Transfer 2 mL platelet-poor plasma to an ARUP Standard Transport Tube. (Min: 1 mL)  
Storage/Transport Temperature
CRITICAL FROZEN. Separate specimens must be submitted when multiple tests are ordered.  
Unacceptable Conditions
Serum. Non-frozen or hemolyzed specimens.  
Ambient: 4 hours; Refrigerated: 8 hours; Frozen: 2 weeks  
Reference Interval
Test Number Components Reference Interval
Factor XIII, Qualitative No Lysis within 24 hours
Factor XIII, 1:1 Mix Not Applicable
Interpretive Data
This is a qualitative screening test; clot lysis only occurs in specimens with severe factor XIII deficiency (less than 1 percent of normal activity). Severe deficiency may be inherited or acquired (typically due to a factor XIII antibody). If clot lysis occurs in the initial testing, then Factor XIII 1:1 Mix will be added where the test is repeated using a 1:1 mix of patient plasma and pooled normal plasma to distinguish between FXIII deficiency and a FXIII inhibitor. Additional charges apply.

False-positive results (lysis) can be caused by heparin (therapy with unfractionated or low molecular weight heparin or contamination from a line), decreased or abnormal fibrinogen, increased fibrinolysis (inherited or acquired fibrinolytic disorders), fibrinolytic drugs, or other factors that affect clot structure or stability.
CPT Code(s)
85291; if reflexed, add additional 85291
Component Test Code*Component Chart Name
2002818Factor XIII, 1:1 Mix
2002915Factor XIII, Qualitative
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Cross References
  • Clot Solubility
  • Factor 13
  • Fibrin Stabilizing Factor