Factor XIII (Fibrin Stabilizing Factor)

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Turnaround Time: 3 - 4 days
CPT Code:


Test Type: 1 mL Plasma, frozen
Reference Range:



This is a screening assay and will detect homozygous deficiency of factor XIII.

This assay is a screening assay only. It will only be abnormal when factor XIII levels are less than 1% to 2%. To determine FXIII activity, a quantitative functional FXIII assay is recommended.

Factor XIII is a large (320 kilodalton) tetrameric molecule that is composed of two A-chains and two B-chains, A2B2.6-8 Factor XIII is activated by thrombin in the presence of calcium. The primary function of activated factor XIII (XIIIa) is to catalyze the formation of covalent bonds between fibrin molecules stabilizing the fibrin clot. Factor XIII converts loosely hydrogen-bonded monomers into covalently bonded fibrin polymer. The resultant clot has increased tensile strength and is resistant to fibrinolysis. Factor XIII deficiency should be considered when a patient with excessive bleeding has both normal protime (PT) and activated partial thromboplastin time (aPTT).6

Congenital factor XIII deficiency is rare (less than one case per million individuals) and is inherited as an autosomal recessive trait.6 Individuals who are heterozygous for the deficiency are generally asymptomatic, although some cases of bleeding in heterozygotes have been reported with provocation.9 Homozygotes have symptoms than can present as umbilical stump bleeding, bleeding after circumcision, and excessive bleeding during teething.6 Intracranial hemorrhage can occur spontaneously in up to 30% of cases. The homozygous condition is associated with spontaneous abortions in females and infertility in males.6 Excessive bleeding can be observed after trauma or surgical procedures and wound healing can be delayed. Acquired deficiency can occur due to autoantibody production to factor XIII. Autoantibody development can sometimes occur in association with certain drugs, including isoniazid, penicillin, and phenytoin.6 Factor XIII levels can also become decreased in individuals with disseminated intravascular coagulation, severe liver disease, acute leukemia, Henoch-Schönlein purpura, Crohn's disease, or ulcerative colitis.7

1. Adcock DM, Kressin DC, Marlar RA. Effect of 3.2% vs 3.8% sodium citrate concentration on routine coagulation testing. Am J Clin Pathol. 1997 Jan; 107(1):105-110. PubMed 8980376

2. Reneke J, Etzell J, Leslie S, Ng VL, Gottfried EL. Prolonged prothrombin time and activated partial thromboplastin time due to underfilled specimen tubes with 109 mmol/L (3.2%) citrate anticoagulant. Am J Clin Pathol. 1998 Jun; 109(6):754-757. PubMed 9620035

3. National Committee for Clinical Laboratory Standardization. Collection, Transport, and Processing of Blood Specimens for Coagulation Testing and General Performance of Coagulation Assays. Approved Guideline. 5th ed. Villanova, Pa: NCCLS; 2008. Document H21-A5:28(5).

4. Gottfried EL, Adachi MM. Prothrombin time and activated partial thromboplastin time can be performed on the first tube. Am J Clin Pathol. 1997 Jun; 107(6):681-683. PubMed 9169665

5. McGlasson DL, More L, Best HA, Norris WL, Doe RH, Ray H. Drawing specimens for coagulation testing: Is a second tube necessary? Clin Lab Sci. 1999 May-Jun; 12(3):137-139. PubMed 10539100

6. Roberts HR, Escobar MA.. Less common congenital disorders of hemostasis. In: Kitchens CS, Alving BM, Kessler CM, eds. Consultative Hemostasis and Thrombosis. Philadelphia, Pa: WB Saunders Co; 2002: 57-71.

7. Adcock DM, Bethel MA, Macy PA. Coagulation Handbook. Aurora, Colo: Esoterix-Colorado Coagulation; 2006.

8. Triplett DA. Coagulation abnormalities. In: McClatchey KD, ed. Clinical Laboratory Medicine. 2nd ed. Philadelphia, Pa: Lippincott Williams and Wilkins; 2002:1033-1049.

9. Schroeder V, Kohler HP. Is heterozygous factor XIII deficiency associated with pregnancy loss? A case report. J Thromb Haemost. 2007; 5(S2):P-w-031.

Collection Details:

Patient Preparation:

Avoid warfarin (Coumadin®) therapy for two weeks and heparin therapy for two days prior to the test. Do not draw from an arm with a heparin lock or heparinized catheter.

Collection Instructions:

If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted.

Blue-top (sodium citrate) tube.

Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.2,3 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples unless the sample is collected using a winged (butterfly) collection system. With a winged blood collection set a discard tube should be drawn first to account for the dead space of the tubing and prevent under-filling of the evacuated tube.4,5 When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternative anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.