Anti-Sa Ab, IgG

Laboratory assay overview

This test can be helpful in the diagnosis of autoimmune rheumatic diseases. Specimens with positive results for antinuclear antibodies (ANA) by indirect immunofluorescence assay (IFA) are subsequently tested for a series of ANA-specific autoantibodies in cascade tiers. The first tier focuses on autoantibodies associated with systemic lupus erythematosus (SLE) and mixed connective tissue disease; the second tier detects autoantibodies seen in Sjogren syndrome, systemic sclerosis and polymyositis; and the third tier includes markers of the limited form of systemic sclerosis and neuropsychiatric SLE. This screen also includes the following markers of rheumatoid arthritis: rheumatoid factor, anti-cyclic citrullinated peptide antibody and anti-mutated citrullinated vimentin antibody. Note that the cascade stops with the first tier in which a positive antibody result is observed. Therefore, even if an antibody included in a subsequent tier is present, it will not be reported with this test. If the ANA IFA result is positive but all the specific autoantibodies tested in the cascade antibody tests are negative, the patient may still have an autoimmune disease other than those typically associated with the antibodies tested.

Laboratory assay overview

This panel can be helpful in the diagnosis of systemic rheumatic disorders and other autoimmune diseases. Although the test for antinuclear antibodies (ANA) is strongly associated with systemic lupus erythematosus (SLE), the laboratory evaluation for individuals with clinical suspicion of a variety of autoimmune diseases often begins with an ANA screen. This panel simultaneously tests for ANA (using immunofluorescence) as well as the important specific autoantibodies associated with a positive ANA. It also includes testing for complement proteins, rheumatoid arthritis, Sjogren's syndrome, systemic sclerosis, polymyositis, anti-phospholipid antibody syndrome, and autoimmune thyroid disease.

Laboratory assay overview

This test is used for rheumatoid arthritis diagnosis, prognosis and management.

Laboratory assay overview

Anti-Citrullinated Vimentin (Sa) antibodies are highly specific for rheumatoid arthritis (RA). They are found in early polyarthritis, can identify patients that are anti-CCP and IgM-RF antibody-negative, and predict a more aggressive RA disease course. Disappearance of anti-Sa IgG antibodies 3 months after initiation of treatment is associated with less radiographic progression.

Laboratory assay overview

A subset of interstitial lung disease (ILD) patients have underlying connective tissue diseases (CTDs). This panel serves as an aid for the diagnosis of CTDs, including rheumatoid arthritis, inflammatory myositis, systemic sclerosis, and Sjogren’s syndrome, that are associated with the development of ILD. If left untreated, these CTD patients may develop lung fibrosis and inflammation. ILD is a direct consequence of these pathological changes. When severe, ILD leads to restrictive lung disease, pulmonary arterial hypertension, and cardiac disease (cor pulmonale).

Laboratory assay overview

Anti-mutated citrullinated vimentin (MCV) antibody is one of several specific anti-citrullinated protein antibodies which may be used as a second-line marker of rheumatoid arthritis (RA), in addition to rheumatoid factor and anti-cyclic citrullinated peptide (CCP). MCV antibody is less specific than CCP but has a slightly higher sensitivity and the addition of MCV to CCP adds 5-10% sensitivity for the diagnosis of RA. MCV antibody positivity is also associated with more severe disease and greater radiologic progression.

Laboratory assay overview

The RAdx6 is a novel comprehensive diagnostic and prognostic panel for rheumatoid arthritis. It combines four novel markers (anti-MCV, anti-CEP-1, anti-Sa and anti-CarP) with two traditional markers anti-CCP and RF) to not only enhance the diagnosis of RA in early or established disease, but also to help predict disease severity. If anti-MCV and/or anti-Sa positivity is present, the disappearance or decrease of these antibodies with treatment is associated with less radiographic progression. In pre-clinical RA, positivity of anti-CEP-1 along with anti-CCP antibodies significantly raises the risk of imminently developing clinical RA. Anti-CarP may predict the development of RA independently of anti-CCP and may be present years before the onset of symptoms in RA. Anti-CarP may confer a 10% incremental benefit in identify early RA and is associated with more active disease and higher risk of developing joint erosions.

Laboratory assay overview

Autoantibody testing has a major role in the diagnosis of RA. This panel includes Rheumatoid factor (RF), anti-cyclic citrullinated peptide (CCP) and anti-mutated citrullinated vimentin (MCV). RF is found in a majority of patients with RA but is not specific for the diagnosis. Anti-CCP antibody is more sensitive and highly specific. RF and anti-CCP are included in the most recent classification criteria for RA. The past several years have seen a search for biomarkers which might increase sensitivity in order to identify the minority of RA patients who are negative for either RF or CCP, especially early in the course of disease. The addition of anti-MCV increases sensitivity for RA when tested together with RF and CCP.

Quest Diagnostics population reference ranges

Quest Diagnostics calculates these statistical intervals for this specific assay and demographic group, not as universal optimal targets.

Laboratory assay overview

SeroNeg RAdx4 is a diagnostic and prognostic panel for rheumatoid arthritis designed to complement traditional RF and anti-CCP testing. This profile, consisting of anti-MCV (mutated citrullinated vimentin) Ab, anti CEP-1 (citrullinated alphaenolase 1) Ab, anti-Sa (citrullinated vimentin) Ab and the novel anti-CarP (carbamylated protein Ab), enhances the diagnosis of established or early RA (especially in individuals seronegative for RF and anti-CCP Ab) and may also help predict disease severity. Decrease in anti-MCV Ab and/or anti-Sa Ab with treatment is associated with less radiographic progression. The presence of anti-CEP-1 and anti-CCP antibodies suggests the imminent progression of pre-clinical RA into clinical RA. Anti-CarP may predict the development of RA independently of anti-CCP and may be present years before the onset of symptoms in RA. Anti-CarP may confer a 10% incremental benefit in identify early RA and is associated with more active disease and higher risk of developing joint erosions.