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)
Qualitative Solubility
2-3 days  
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
Lt. blue (sodium citrate). Refer to Specimen Handling at 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. EDTA plasma or hemolyzed specimens.  
Ambient: 4 hours; Refrigerated: Unacceptable; 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 NameLOINC
2002818Factor XIII, 1:1 Mix3241-7
2002915Factor XIII, Qualitative3241-7
* 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.
  • Clot Solubility
  • Factor 13
  • Fibrin Stabilizing Factor