Reference Range
Anti-Ro antibodies, also known as anti-SSA antibodies, are associated with Sjögren syndrome.
Anti-Ro antibodies, immunoglobulin G (IgG) [1] :
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< 1 U (negative)
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≥ 1 U (positive)
Interpretation
A positive anti-Ro result is indicated by a speckled appearance under immunofluorescence with ultraviolet light.
Anti-Ro levels may be elevated in the following conditions: [1]
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Sjögren syndrome: 60-70% of cases
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Systemic lupus erythematosus (SLE): 25% of cases
Both anti-Ro/SSA and anti-La/SSB are usually absent in secondary Sjögren syndrome. [2]
When anti-Ro/SSA levels are elevated in SLE, it is often in antinuclear antibody (ANA)–negative lupus. [2]
Anti-Ro/SSA plus anti-La/SSB is associated with the following factors: [3]
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Age older than 50 years
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HLA-DR3
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Lower likelihood of anti-DNA antibodies
Anti-Ro/SSA without anti-La/SSB is associated with the following factors: [3]
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Age younger than 22 years
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HLA-DR2
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Worse renal manifestations
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Increased likelihood of anti-DNA antibodies
Collection/Panels
There are no special collection conditions or timings.
Draw in a standard red-top tube.
Hemolysis and lipemia should not affect the results but should be avoided, if possible.
There are no special storage conditions.
It is usually not part of a laboratory panel.
Background
Description
Anti-Ro antibodies are associated with Sjögren syndrome.
Sjögren syndrome is often characterized by xerostomia and xerophthalmia-type symptoms. A diagnosis of Sjögren syndrome requires a minimum of 3 of the 4 following criteria: [4]
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Positive Schirmer test result or Rose Bengal score
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Histological grading of the minor salivary glands with a focus score of greater than 1
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Salivary flow of less than 1.5 mL in 15 minutes
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Anti-Ro/SSA and/or anti-La/SSB antibodies
At this time, no conclusive evidence indicates that any single laboratory technique provides superior sensitivities or specificities.
Indications/Applications
Anti-Ro, along with other autoantibody levels, should be obtained when a rheumatologic/connective tissue disorder is suspected, specifically if the following conditions manifest or are suspected: [2, 3]
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Photosensitivity or subacute cutaneous lupus
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Primary Sjögren syndrome vasculitis
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Cutaneous vasculitis/palpable purpura
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Interstitial lung disease
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Neonatal lupus
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Congenital heart block
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ANA-negative SLE
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Nephritis, vasculitis, lymphadenopathy, leukopenia
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Homozygous C2 and C4 deficiency with SLE-like disease
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Rheumatoid factor positivity and severe systemic symptoms
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SLE with interstitial pneumonitis