Can't understand the common indicators of rheumatology?

*Only for medical professionals to read and reference, no longer afraid of looking at the laboratory test! For many departments, blood routine, liver and kidney function, and coagulation function are routine examinations, but for the rheumatology department, various antibodies and inflammatory indicators are also routine examinations (rheumatology department? Yes! It is in the eighth edition The proportion of the internal medicine book is the least, but every sentence is the key point, the legendary "rheumatology and immunology")
.

The role of antibodies and inflammatory indicators on rheumatic immune diseases is self-evident.
Today, Jiemei will take a good look at the role of these indicators, so that everyone will no longer be afraid of them! C-reactive protein (CRP) must first be introduced to the "frequent visitor" of rheumatology and immunology - CRP
.

CRP is one of the acute phase reaction proteins.
In 1930, Tillett and Fransic from the AVERY Laboratory of the Rockefeller Institute in the United States found that the serum of patients with acute infection could precipitate with C polysaccharide on the cell wall of pneumococcus, and it was later confirmed that a reaction was involved in the reaction.
This protein is called C-reactive protein
.

 ■ Indicators of infection It is well known that serum CRP level is a sensitive and objective indicator of bacterial infection
.

During bacterial infection, the level of serum CRP can be moderately to significantly increased, and the positive rate can reach more than 90%, while during viral infection, the level of CRP is usually normal or slightly increased, so it can help bacterial infection and non-bacterial infection.
differential diagnosis
.

 ■ Rheumatoid arthritis (RA) In addition to infectious diseases, CRP also has high application value in connective tissue diseases, such as RA, juvenile idiopathic arthritis, systemic vasculitis, etc.
, CRP level is one of the important predictors of early RA joint destruction and prognosis [1]
.

That's why it's important to test for CRP during patient re-examinations to monitor disease activity! ■ Of particular importance in systemic lupus erythematosus (SLE), CRP can be elevated both during SLE disease activity and during infection, but the level of elevation varies.
In active patients, CRP is also only mildly elevated (usually <60 mg/L)
.

However, CRP levels were moderately elevated (mean, 76 mg/L) in SLE with serositis, regardless of co-infection.
Therefore, in SLE patients without serositis, CRP levels are important for distinguishing between SLE disease activity or SLE disease activity.
Infection is important
.

The higher the CRP level, the higher the possibility of infection [2]
.

 ■ Other rheumatic immune diseases In addition, in the active phase of ankylosing spondylitis (AS), psoriatic arthritis and other diseases, plasma CRP can also be elevated
.

CRP is also associated with various complications such as atherosclerosis and osteoporosis in connective tissue diseases
.

 Erythrocyte Sedimentation Rate (ESR) ESR refers to the sedimentation rate of red blood cells under certain conditions.
It is generally expressed by the sedimentation distance in the erythrocyte sedimentation tube within one hour at room temperature (18-25°C).
ESR has different changes in different diseases.
, higher ESR can be found in inflammatory diseases, tumors, anemia,
etc.

In rheumatism, ESR is often closely related to the severity and prognosis of the disease, and is also an important indicator of standard treatment
.

 ■ RAESR is in the classification and diagnostic criteria of RA, but elevated ESR does not mean RA, and it is often used to evaluate disease activity and response to treatment
.

The ESR of RA patients tends to be significantly increased when the disease is active, and when most patients achieve remission after treatment, the ESR is normal
.

 ■ SLE is similar to RA.
ESR increases during SLE disease activity, and ESR decline has important implications for SLE disease remission.
However, studies have shown that there is no significant difference in ESR between SLE patients with disease activity without infection and disease activity with infection.
Disease activity and infection do not have a role in distinguishing and prompting [3-4]
.

 ■ Sjogren's Syndrome (pSS) Because of local or systemic inflammatory lesions and characteristic hyperglobulinemia in pSS, ESR in pSS is significantly higher than that in healthy people, and studies have shown that ESR is closely related to anti-SSA antibodies, anti-SSB antibodies, immune globulin protein related
.

 ■ Polymyositis/dermatomyositis (PM/DM) Fever is the most common clinical manifestation in PM/DM.
Elevated ESR is highly correlated with PM/DM disease activity and is one of the poor prognostic indicators of PM/DM.
Levels of ESR are often associated with interstitial pneumonia, respiratory failure, and poor response to treatment
.

 ■ Other rheumatic diseases In adult Still's disease, the proportion of serum ferritin is significantly increased, but not necessarily proportional to the increase in acute phase reactants, and the increase in CRP is more pronounced than in ESR
.

In systemic sclerosis, approximately one-quarter of patients have elevated ESR, and elevated ESR is associated with poor disease prognosis
.

In addition, in crystal arthritis, psoriasis, reactive arthritis and infectious arthritis, ESR is also generally elevated, and it is closely related to disease assessment
.

Rheumatoid factor (RF) Seeing rheumatoid factor, many people naturally think of rheumatoid arthritis.
After all, the two words overlap so much! That's right! RF is the earliest serological diagnostic index used in RA, and it has high sensitivity for diagnosing RA.
Therefore, it is used as the only serological index in the RA classification and diagnostic criteria formulated by the American College of Rheumatology (ACR) in 1987
.

However, it should be noted that in other connective tissue diseases (SS, SLE, scleroderma, mixed connective tissue disease, etc.
), infections and tumors, RF is also positive, so its specificity for diagnosing RA is low
.

Anti-cyclic citrullinated peptide (CCP) antibody Anti-CCP antibody is a polypeptide fragment of cyclic filaggrin secreted by plasma cells with the function of secreting anti-CCP antibodies.
It is mainly an IgG-type antibody.
Aminopeptides can interact with keratin granules around the nucleus of human capsular epithelial cells, resulting in specific reactions
.

 Anti-CCP antibody is a new serological indicator for the diagnosis of RA
.

Studies have shown that anti-CCP antibodies have high sensitivity and specificity in the diagnosis of RA [5], not only can basically detect RA patients detected by RF, but also detect more RA patients that cannot be detected by RF
.

Because B lymphocytes do not spontaneously secrete anti-CCP antibodies in patients with other diseases and normal populations, but only B lymphocytes in RA patients spontaneously secrete anti-CCP antibodies, the specificity for diagnosing RA is high
.

At the same time, the bone destruction in RA patients with positive anti-CCP antibody was more serious than that in those with negative antibody, suggesting that the content of anti-CCP antibody is related to the severity and development of RA
.

Therefore, anti-CCP antibody is a "filling in the gap" for RF, and the combined detection of RF + anti-CCP antibody is helpful for the diagnosis of RA
.

 Anti-keratin antibody (AKA) The target antigen of anti-CCP antibody and AKA is mainly cytoplasmic polykeratin, and this protein component is the main component of RF antigen, which is helpful for the early diagnosis of RA by RF
.

The specificity of AKA is comparable to that of RF and anti-CCP antibodies, but the sensitivity is significantly lower, and it is easy to be missed
.

 Anti-nuclear antibody (ANA) ANA detection is the first choice for autoimmune disease screening.
ANA is a group of autoantibodies produced against DNA, RNA proteins or molecular complexes of these substances in the nucleus [6]
.

It has the highest sensitivity for SLE, but poor specificity (not only exclusive to SLE, but also found in healthy people, RA, scleroderma, DM, SS and other rheumatism and infectious diseases), so it is often used in clinical screening experiments
.

In clinical diagnosis, using ANA alone as the diagnostic basis for patients has certain risks of misdiagnosis and missed diagnosis
.

 Anti-ENA antibody spectrum Anti-ENA antibody mainly refers to extractable nuclear antigen antibodies, including several kinds of antibodies, each antibody plays a different role in the process of disease diagnosis, and some antigens only exist in the pathogenesis of a certain disease.
, can indicate this disease
.

Commonly used anti-ENA antibodies mainly include anti-Sm, U1-RNP, anti-SSA/SSB antibodies, Jo-1, Scl-70, anti-centromere antibodies, and ribosomal P protein antibodies
.

 Anti-Sm antibody only appears in SLE, so it can be used as a specific indicator of SLE
.

Anti-U1-RNP antibodies can appear in a variety of rheumatic diseases, but high titers of anti-U1-RNP antibodies have diagnostic significance for mixed connective tissue disease
.

Anti-SSA antibodies: the most common in SS, also found in SLE, RA,
etc.

Anti-SSB antibodies: common in SS and SLE
.

Anti-Scl-70 antibody: common in diffuse progressive systemic sclerosis
.

Anti-Jo-1 antibody: more common in polymyositis
.

Anticentromere antibodies: common in limited progressive systemic sclerosis
.

Ribosomal P protein antibody: It is a specific antibody for SLE, which is rare in other diseases and normal people
.

Anti-nucleosome antibodies: mainly seen in SLE
.

Anti-histone antibodies: mainly seen in drug-induced lupus, but also in SLE and RA
.

Therefore, the isolation of each antigen is very important for the diagnosis and treatment of patients with autoimmune diseases and the diagnosis of the disease
.

 Anti-ds-DNA Antibodies High concentrations of anti-ds-DNA antibodies are only present in the SLE population and thus serve as specific detection antibodies
.

Clinical diagnosis and treatment experience has found that the level of anti-ds-DNA antibody varies with the patient's condition.
In the early stage of the disease and after the disease is controlled, the level of anti-ds-DNA antibody is at a low level
.

That is to say, if the level of anti-ds-DNA antibodies is high, then the diagnosis of SLE is more likely, and this indicator can also detect disease activity! However, anti-ds-DNA antibodies can also exist in rheumatism and hepatobiliary diseases such as RA and SS
.

There are more than ten kinds of target antigens of ANCAANCA, the most clinically relevant ones are protease 3 (PR3) and myeloperoxidase (MPO), both of which are related to ANCA-related vasculitis, namely granulomatosis with polyangiitis (GPA), Acid granulomatosis with polyangiitis (EGPA), microscopic polyangiitis (MPA), and the renal manifestations of these diseases are closely related
.

Human leukocyte antigen B27 (HLA-B27) was first reported by Brewerton and Schlosstein in 1973 to be associated with AS.
HLA-B27 is the gene with the strongest association with AS currently known
.

90% of AS patients tested positive for the HLA-B27 gene
.

Only about 4% to 7% of the normal population, HLA-B27 is closely related to the pathogenesis of AS
.

Summary In the diagnosis of rheumatic immune diseases, the detection of various types of antibodies is of course important, but the clinical interpretation of antibodies needs to be combined with the clinical symptoms, medical history and signs of patients, and horizontal comparison analysis is required if necessary
.

At present, research on emerging antibodies in rheumatic immune diseases is continuing, and it is expected that more indicators will play more roles in the clinical diagnosis and treatment of rheumatic immune diseases in the future
.

 References[1] Scott DL.
Prognostic factors in early rheumatoid arthritis[J].
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[2] Szalai AJ .
C-reactive protein ( CRP ) and autoimmune disease: facts and conjectures [J].
Clin Dev Immunol, 2004, 11:221-226.
[3] Zhang Shengli, Lin He, Huang Feng.
Systemic autoimmune rheumatism comorbid infection: the special judgment value of C-reactive protein[J].
Zhonghua Journal of Internal Medicine, 2020, 59(7): 489-492.
DOI: 10.
3760/cma.
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cn112138-20191202-00789.
[4] Littlejohn E, Marder W, Lewis E, et al.
The ratio of erythrocyte sedimentation rate to C-reactive protein is useful in distinguishing infection from flare in systemic lupus erythematosus patients presenting with fever.
Lupus.
2018 Jun;27(7):1123-1129.
[5] Huo AP, Lin KC, Chou CT.
Predictive and prognostic value of antinu-clear antibodies and rheumatoid factor in primary Sjogren's syndrome [J].
Int J Rheum Dis, 2010, 13(1): 39-47.
[6] UgurluS, KaracanI, OzdoganH, et al.