Ordering RecommendationRecommendations when to order or not order the test. May include related or preferred tests.
Recommended for the diagnosis of systemic sclerosis in patients negative for centromere, Scl-70, or RNA polymerase III antibodies. May predict skeletal muscle involvement and pulmonary arterial hypertension.
MnemonicUnique test identifier.
U3 FIB
MethodologyProcess(es) used to perform the test.
Qualitative Immunoblot
PerformedDays of the week the test is performed.
Tue, Thu, Sat
ReportedExpected turnaround time for a result, beginning when ARUP has received the specimen.
1-4 days
New York DOH Approval StatusIndicates test has been approved by the New York State Department of Health.
This test is New York DOH approved.
Specimen Required
Patient Preparation
Collect
Serum separator tube.
Specimen Preparation
Transfer 1 mL serum to an ARUP Standard Transport Tube. (Min: 0.5 mL)
Storage/Transport Temperature
Refrigerated. Also acceptable: Frozen.
Unacceptable Conditions
Grossly hemolyzed or severely lipemic.
Remarks
Stability
After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year
Reference IntervalNormal range/expected value(s) for a specific disease state. May also include abnormal ranges.
Negative
Interpretive DataBackground information for test. May include disease information, patient result explanation, recommendations, details of testing, associated diseases, explanation of possible patient results.
The presence of fibrillarin (U3-RNP) IgG antibodies in association with an ANA IFA nucleolar pattern is suggestive of systemic sclerosis (SSc). In SSc, these antibodies are associated with distinct clinical features, such as younger age at disease onset, frequent internal organ involvement (pulmonary hypertension, myositis and renal disease). Fibrillarin antibodies are detected more frequently in African American patients with SSc compared to other ethnic groups. Strong correlation with ANA IFA results is recommended.
In a multi-ethnic cohort of SSc patients (n=98), U3-RNP antibodies detected by immunoblot had an agreement of 98.9 percent with the gold standard immunoprecipitation (IP) assay. Approximately 71 percent (5/7) of the borderline U3-RNP results with ANA nucleolar pattern in this cohort were IP negative.
This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.
Compliance Category
Laboratory Developed Test (LDT)
NoteAdditional information related to the test.
Hotline History
N/A
CPT CodesThe American Medical Association Current Procedural Terminology (CPT) codes published in ARUP's Laboratory Test Directory are provided for informational purposes only. The codes reflect our interpretation of CPT coding requirements based upon AMA guidelines published annually. CPT codes are provided only as guidance to assist clients with billing. ARUP strongly recommends that clients confirm CPT codes with their Medicare administrative contractor, as requirements may differ. CPT coding is the sole responsibility of the billing party. ARUP Laboratories assumes no responsibility for billing errors due to reliance on the CPT codes published.
* 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.
AliasesOther names that describe the test. Synonyms.
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