1.Rheumatoid factor (RF)
In addition to rheumatoid arthritis, rheumatoid factor is also seen in other rheumatic immune diseases, non-rheumatic diseases, and even in healthy people.
Clinically, a positive rheumatoid factor needs to be considered from various aspects.
(1) Viral infectious diseases, such as hepatitis and infectious mononucleosis.
(2) Chronic bacterial diseases, such as tuberculosis, leprosy, subacute endocarditis.
(3) Other rheumatic diseases, such as systemic lupus erythematosus, dry syndrome.
(4) de novo tumors after radiotherapy or cytotoxic drug therapy.
(5) Parasitic infections, such as trypanosomiasis.
(6) Even some healthy people.
2.Blood sedimentation (ESR)
Blood sedimentation, i.e. erythrocyte sedimentation rate, refers to the rate of sedimentation of erythrocytes under certain conditions. The current hematocrit value, determined by the Weiss method, refers to the number of millimeters of vertical descent of red blood cells in the hematocrit tube at the end of the first hour. The normal sedimentation value is less than 15 mm/h for healthy adult males and less than 20 mm/h for females. There are many factors affecting the sedimentation, so the sedimentation is a non-specific indicator. However, if the blood sedimentation continues to increase significantly, it mostly indicates the presence of lesions. It is generally considered that the blood sedimentation measured by the Weiss method is mildly increased up to 25mm/h and severely increased up to 50mm/h. Under physiological conditions, such as women who are menstruating, pregnant for more than 3 months, and elderly people over 60 years old, the hematocrit can be mildly increased.
Increased hematocrit is mainly seen in the following pathological conditions.
(1) Various inflammatory diseases: such as tuberculosis, rheumatic fever, etc. It is often used clinically to determine the activity of the disease and as a dynamic observation indicator.
(2) Tissue injury and necrosis: such as after surgery or trauma, myocardial infarction, etc.
(3) Malignant tumor: It can be used as a criterion for screening and judging the efficacy of malignant tumor.
(4) Hyperglobulinemia: such as systemic lupus erythematosus, rheumatoid arthritis and other diseases.
(5) Anemia.
(6) Hypercholesterolemia.
3.Anti-nuclear antibody (ANA)
4. ENA peptide antibody profile
Anti-ENA antibody is an autoantibody against nuclear antigen extractable in the nucleus of cells, which is also called saline-extractable nuclear antigen because its antigen can be dissolved in isotonic saline. They also constitute the anti-ENA antibody spectrum because of the complex antigenic composition of them.
The following are currently in common use.
(1) Anti-Sm antibodies
Named after the patient’s name (Smith). Anti-Sm antibodies have important diagnostic value in early, atypical SLE.
(2) Anti-nRNP antibodies
Because of its uracil (U) rich content, nRNP is also commonly referred to as U1RNP. anti-U1RNP antibody is almost always positive in mixed connective tissue disease and shows high titers, making it an important indicator for the diagnosis of mixed connective tissue disease. It is also a powerful indicator for differentiating connective tissue disease from non-connective tissue disease.
(3) Anti-SSA antibody and anti-SSB antibody
These two antibodies are associated with dry syndrome. In patients with primary dry syndrome, the positive rates of anti-SSA antibody and anti-SSB antibody are 60% and 40%, respectively, but they can also be present in other connective tissue diseases. Anti-SSB antibodies are more significant than anti-SSA antibodies in diagnosing desiccation syndrome.
(4) Anti-Scl-70 antibody
The anti-Scl-70 antibody is named for the fact that it is found mainly in systemic sclerosis and has an antigen molecular weight of 70 kD. Anti-Scl-70 antibodies are very specific to systemic sclerosis and are rarely detected in other connective tissue diseases.
(5) Anti-Jo-1 antibody
Named after the patient’s name John. Anti-Jo-1 antibody is considered a marker antibody for polymyositis and is rarely found in other rheumatic diseases.
(6) Anti-rRNP antibodies
are often present in patients with active SLE and in those with visceral damage (e.g., encephalopathy), paralleling the waxing and waning of anti-dsDNA antibodies. It is a valuable antibody for the diagnosis of SLE, as it is positive in up to 40% of SLE patients in the active phase.
(7) Anti-RA33 antibody
This antibody can be found in early rheumatoid arthritis and is useful for the early diagnosis of rheumatoid arthritis. Osteoarthritis, ankylosing spondylitis, and psoriatic arthritis do not show this antibody, so anti-RA33 antibody is currently considered as one of the indicators to differentiate rheumatoid arthritis from other arthritis.
5. Anti-double-stranded DNA antibody (anti-ds-DNA antibody)
Anti-ds-DNA antibody is present in 70% of patients with lupus at some stage of their disease. It has a specificity of 95% for the diagnosis of lupus and therefore has a high diagnostic value and parallels the activity of SLE and serves as an estimator of treatment. As disease activity is controlled, anti-dsDNA antibody titers can decrease or disappear. Anti-dsDNA antibodies bind to DNA to become immune complexes deposited in the glomerular basement membrane or anti-dsDNA antibodies act directly on glomerular antigens causing renal damage in patients with SLE. However, some asymptomatic patients may also have persistently high levels of anti-ds-DNA.
6. Anti-cyclic citrulline antibodies (CCP)
The main clinical significance of the anti-CCP antibody test is.
(1) high specificity (90. 4%-98%) and not poor sensitivity (46. 6%-75. 8%) for the diagnosis of rheumatoid arthritis. The diagnostic sensitivity was comparable to that of rheumatoid factor but with higher specificity, and the specificity was comparable to that of anti-perinuclear factor antibodies, while the sensitivity was higher. Although anti-CCP antibody, anti-perinuclear factor, anti-keratin antibody and rheumatoid factor have high concordance, they cannot be substituted for each other, and the specificity of diagnosis can be further improved if these four antibodies are tested simultaneously.
(2) Contribute to the early diagnosis of rheumatoid arthritis: The antibody can precede the clinical manifestations of the disease and therefore predict the progression of patients from general arthritis to rheumatoid arthritis. It has a sensitivity of 73.3% and a specificity of 92.6% for rheumatoid arthritis, with positive and negative predictive values of 91.7% and 75.7%, respectively, which are better than rheumatoid factor and antiperinuclear factor antibodies.
(3) May be associated with the activity of rheumatoid arthritis, but this needs to be confirmed by a large number of case data studies.
(4) Suggests prognosis: In recent years, it has been found that patients with rheumatoid arthritis who are positive for anti-CCP antibodies have more severe bone destruction than those who are negative. The level of anti-CCP antibody is related to the severity and progression of rheumatoid arthritis. The prognosis can be judged by the level of concentration.
7.Glucose 6 phosphate isomerase (GPI)
The presence of GPI in the serum and joint cavity fluid of patients with rheumatoid arthritis (RA) and about 64% of the healthy population with uncontrolled rheumatoid arthritis is a unique autoimmune physiological function of rheumatoid arthritis. The presence of highly potent GPI in patients with RA is often accompanied by severe joint functional limitations. This suggests a poor prognosis or that the medication did not play a role in the treatment process. When RA patients improve with medication, the GPI in the serum and joint cavity fluid decreases and joint swelling and pain is reduced.
8.Anti-neutrophil cytoplasmic antibody (ANCA)
ANCA is an autoantibody that targets the cytoplasmic components of neutrophils and monocytes, and is a specific antibody detected in the sera of most primary small vessel vasculitis diseases.ANCA is generally tested by indirect immunofluorescence (IIF), and is classified into three types according to the triple fluorescence pattern it produces. However, it should be noted that pANCA is difficult to distinguish from ANA in the IIF test, and care should be taken when judging the results. PR3), which is the main target antigen of cANCA. Myeloperoxidase (MPO), which is the main target antigen of pANCA. The clinical significance is that pANCA positivity is mainly seen in microscopic vasculitis (MPA), ANCA-associated necrotizing crescentic nephritis (NCGN), inflammatory bowel disease, autoimmune liver disease and SLE; cANCA positivity is mainly seen in Wegener’s granulomatosis (WG) and some MPO; atypical ANCA is seen in cystic fibrosis, infectious diseases and rheumatoid arthritis.
9.Anti-mitochondrial antibody (AMA)
Patients with primary biliary cirrhosis have a positive AMA rate of more than 90%, and the antibody titer is very high, more than half of the patients can reach 1:200-1:6,000. patients with choledochal obstructive cirrhosis and secondary biliary cirrhosis are negative for anti-mitochondrial antibody. The positive rate in patients with obstructive cirrhosis is less than 3%, while the positive rate in chronic active hepatitis is 90%. The rate of positivity in normal subjects was less than 1%. Accordingly, the test for anti-mitochondrial antibodies can be used as a differential diagnosis between primary biliary cirrhosis and extrahepatic biliary obstructive cirrhosis. In addition, since the positive rate of this antibody is also higher in chronic active hepatitis, it is also useful for differential diagnosis of hepatitis.
10.Blood test
Most of the rheumatic diseases will cause blood routine abnormalities, manifested as reduced or increased white blood cells, abnormal platelets, and even decreased triple system.
11.Urinary routine
Systemic lupus erythematosus will cause proteinuria.
12.Magnetic resonance imaging
With the rapid development of imaging, its application in the diagnosis of rheumatic diseases is becoming more and more important and widespread, especially the application of computerized X-ray tomography (CT) and magnetic resonance imaging (MRI), which makes certain diseases can be clearly diagnosed in the early stage, providing valuable time for the diagnosis and treatment of patients and reducing their pain. Magnetic resonance imaging is used in diseases such as rheumatoid arthritis, polymyositis/dermatomyositis, and osteoarthritis.
MRI can determine the macroscopic condition of synovial inflammation, such as the degree and extent of fibrin exudation, cellular infiltration, vascular proliferation and granuloma (vascular opacity) formation, synovial villus and synovial hypertrophy in the early stages of arthritis and its lesion activity when synovial volume changes. It is also possible to distinguish myositis, fascial tension, fatty infiltration and hypertrophy and inflammation waxing and waning. It can clearly show the state of cervical dislocation, spinal cord compression and spinal cord distortion.