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Test ID: ENA RNP
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ENA RNP
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Anti-nuclear ribnucleoprotein (anti-nRNP) antibodies
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Useful For
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The positive test result for antinuclear antibodies (CTD) is important for the clinical diagnosis of patients with signs and symptoms of connective tissue disease. Evaluating the patient with Extractable Nuclear Antigens U1RNP (ENA RNP) can help in the clinical diagnosis of mixed connective tissue disease (MCTD) and systemic lupus erythematosus (SLE).
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Method name and description
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Method: Fluorescence Enzyme Immunoassay (FEIA), Uses the EliA IgG method on Phadia system.
Using EliA technology solid phase, analyte molecules can be extracted from a sample. To achieve this, a well is coated with an antigen that specifically binds to target antibodies. Following the removal of non-bound antibodies, enzyme-labeled antibodies against human antibodies (EliA IgG Conjugate) are added to form an antibody conjugate complex. This complex is then incubated and non-bound conjugate is subsequently washed away. The bound complex is then incubated with a Development Solution, and after stopping the reaction, the fluorescence in the reaction mixture is measured. A higher response value indicates the presence of a more specific antibody in the specimen.
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Clinical information
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The determination of antinuclear antibodies (ANA) is central importance for the clinical diagnosis of connective tissue diseases. U1-snRNP antibodies typically appear in both SLE and mixed connective tissue disease (MCTD, Sharp Syndrome). In MCTD, the presence of U1-snRNP antibodies is required for diagnosis, whereas they occur in only 30 to 40 % of SLE patients. Although the anti-U1-snRNP immune response comprises antibodies against all 3 protein components (70 kDa, A, C), 70 kDa antibodies - particularly in case of high titers - may be more specific for MCTD, as they have been reported to occur less frequently in SLE (approximately 12 %) than antibodies against A or C proteins (approximately 23 %). Several studies have shown that an anti-U1-snRNP response in the absence of 70 kDa antibodies is strongly associated with SLE.
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Aliases
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ENA RNP
Anti-U1RNP
Autoantibodies to RNP
Ribonucleoprotein Autoantibodies
Anti-nuclear ribnucleoprotein (anti-nRNP) antibodies
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Specimen type / Specimen volume / Specimen container
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Specimen type: Serum sample.
Specimen Volume: At minimum 2 mL whole blood or 0.5 mL serum.
Container Tube: Plan tube /Serum gel (Yellow top tubes).
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Storage and transport instructions
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For sample transportation, the sample should remain at room temperature (18-25°C ) for no longer than eight hours.
Separated serum samples can be stored at 2-8°C for one week.
Separated serum samples should be frozen at below -20°C for any long-term storage.
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Specimen Rejection Criteria
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Quantity not sufficient (QNS)
Hemolysis
Lipemic
Wrong collection container
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Biological reference intervals and clinical decision values
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Anti-ENA U1RNP antibodies:
| Interpretation of Test Results |
Reference Values (U/ml) |
| Negative |
< 5 |
| Equivocal |
5 - 10 |
| Positive |
> 10 |
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Turnaround time / Days and times test performed / Specimen retention time
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Turnaround Time: 5 working days.
Days and Times test performed: Twice per week starting from Sunday through Thursday from 7:00 to 15:00.
Specimen retention time: Approximately 7 days.
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