HERMANN TEST CODE: 26-00390
CPT CODE: 85291
SPECIMEN REQUIREMENT: 5 mL blood (minimum 4.5 ml), blue top tube (sodium citrate), mixed well.
TEST AVAILABILITY: Performed by Coagulation Section in Hermann Laboratory, Mon-Fri, 7 AM-3 PM. Reporting time in 24 hours. Specimen must be in the laboratory by 9 AM to be performed on the same day
METHODOLOGY: Clot lysis in 5M Urea
CLINICAL UTILIZATION: Diagnosis of Factor XIII Deficiency
REFERENCE RANGE: No clot lysis up to 24 hour incubation (Factor XIII should be at least 2%)
INTERPRETATION:
Factor XIII is converted to its active form, F XIIIa, by thrombin. In the presence of calcium, factor XIIIa catalyzes the formation of covalent bond between adjacent fibrin monomers. This stabilizes the fibrin clot, making it resistant to the lytic action of plasmin. Factor XIII also promotes the cross-linking of alpha-2-antiplasmin to fibrin, increasing the resistance to fibrin degradation. Congenital deficiency of Factor XIII, inherited as an autosomal recessive disorder, may result in a bleeding diathesis. Only homozygotes with a very low level of Factor XIII may exhibit a bleeding tendency, since a Factor XIII of more than 5% is usually adequate for hemostasis.
A workup for Factor XIII deficiency should only be pursued in patients with a bleeding diathesis after other causes of bleeding have been excluded using the more common tests such as Prothrombin Time (PT), activated Partial Thromboplastin Time (aPTT), Fibrinogen, Thrombin Time (TT), and Platelet Count. These screening tests are typically normal in patients with Factor XIII deficiency.
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