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. Refer to Factor XIII Activity (2006182).

Qualitative Solubility
2-3 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
ARUP Consult®
Disease Topics
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, clotted or hemolyzed specimens. 
Ambient: 4 hours; Refrigerated: Unacceptable; Frozen: 2 weeks 
Reference Interval
Test Number
Reference Interval
Factor XIII, QualitativeNo Lysis within 24 hours
 Factor XIII, 1:1 MixNot 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