What is RNP SM blood test?
What is RNP SM blood test?
Sm/RNP Antibody – Smith (Sm)/U1-RNP Antibody is detected in patients with mixed connective tissue disease (having features of systemic lupus erythematosus (SLE), scleroderma, and polymyositis).
What does it mean if you have RNP antibodies?
Antibodies to ribonucleoprotein, RNP, are found often in very high levels in patients with a variety of systemic rheumatic diseases, including SLE, progressive systemic sclerosis and Mixed Connective Tissue Disease, a distinct disease entity with overlapping clinical features of SLE, scleroderma, polymyositis and …
What does it mean to have a positive SM antibody test?
A positive result for anti-Sm antibodies is consistent with a diagnosis of lupus erythematosus.
What is RNP AB test?
The anti-RNP test usually involves ELISA for the quantitative measurement of immunoglobulin G (IgG) class autoantibodies. While the detection of anti-RNP antibodies is consistent with MCTD, it is not diagnostic; a patient may have high levels of anti-RNP and present with no clinical signs of disease.
What does a negative SM antibody mean?
As a diagnostic test, anti-Sm antibodies have a relatively low sensitivity but high specificity; thus, a positive test result is very useful in confirming the diagnosis. However, a negative test result does not exclude the diagnosis of SLE.
What is the SM antibody?
Although anti-Smith (Sm) antibody is a highly specific antibody for systemic lupus erythematosus (SLE), the significance of anti-Sm antibody in patients with SLE is unclear. This study aimed to evaluate the association between anti-Sm antibodies and disease activity in patients with new-onset SLE.
How are anti-Sm and anti-RNP antibodies detected?
Anti-Sm and anti-RNP antibodies are directed towards both discontinuous and linear epitopes which are either contained in the protein sequence or are post-translationally modified. The assays to detect anti-Sm and anti-RNP antibodies are counterimmunoelectrophoresis (CIE), immunoblot, and ELISA, based on purified or recombinant proteins …
What kind of blood test is RNP positive for?
One of the most common diseases that this blood test is used to detect is lupus, but there is only a 30% positive test result rate when RNP antibodies are present.
What kind of antibodies are used for SM?
Anti-Sm antibodies are directed against 7 proteins (B/B’, D1, D2, D3, E, F, G) that constitute the common core of U1, U2, U4 and U5 small nuclear ribonucleoprotein (snRNP) particles; B/B … Among anti-nuclear antibodies, anti-Sm and anti-RNP antibodies are of the utmost importance in clinical practice.
What do you need to know about negative ANA test for lupus?
People with lupus who have a negative ANA test may have anti-Ro/SSA or antiphospholipid antibodies. In people with a positive ANA, more tests are usually performed to check for other antibodies that can help to confirm the diagnosis.
What are the titers of SM and RNP antibodies?
High titers of Sm and RNP antibodies have been reported in patients with less renal and central nervous system disease, though others have refuted these findings. Sm antibodies may disappear with treatment, while RNP antibodies persist.
Can a SM antibody disappear with RNP treatment?
Sm antibodies may disappear with treatment, while RNP antibodies persist. Many patients present with clinical signs and symptoms that are compatible with more than one systemic rheumatic disease.
Are there any negative clinical significance for SM?
Negative Clinical Significance: Antibodies to Sm are highly specific for systemic lupus erythematosus (SLE) and when present are considered a marker antibody. However, these antibodies are found in only 20% of patients with SLE.
Can you test for RNP antibodies in Sera?
Testing for RNP antibodies is not useful in patients without demonstrable antinuclear antibodies. RNP (also called nRNP and U1RNP) is a small nuclear ribonucleoprotein that contains 3 protein autoantigens (called A, C, and 68 kD). Sera that contain RNP antibodies react predominately with the A and 68-kD autoantigens.