A summary of rheumatology test items

Rheumatism has a wide variety of diseases, complex conditions, in the process of patient diagnosis and treatment, a variety of laboratory tests are essential, and the results of the examination is also a very complex problem, often need doctors combined with the comprehensive analysis and judgment of the patient's condition, in order to make a more objective and correct diagnosis
.

Here are some common rheumatology laboratory indicators:

Introduction and classification of rheumatology

In a broad sense, it is believed that all diseases that cause bone and joint and muscle pain can be classified as rheumatism
.
Continued, so far, in the classification of rheumatism, there are more than 100 diseases in a broad sense, including infectious, immune, metabolic, endocrine, hereditary, degenerative, neoplastic, endemic, toxic and other diseases
caused by various reasons.
In a narrow sense, it should be limited to a few dozen diseases
related to internal medicine and immunity.
Some of these diseases are interdisciplinary, such as gout, osteoarthrosis, infectious arthritis, etc
.

The classification of diseases is as follows

1.
Arthritis-based: such as rheumatoid arthritis (A), Still disease is divided into juvenile and adult type, ankylosing spondylitis (AS), psoriatic arthritis
.

2.
Infection-related: such as rheumatic fever, Lyme disease, Reiter syndrome, reactive arthritis
.

3.
Diffuse connective tissue disease: systemic lupus erythematosus (SLE), primary Sjogren syndrome (pSS), systemic sclerosis (SSc), polymyositis (PM), dermatomyositis (DM), mixed connective tissue disease (MCTD), vasculitis
.

Rheumatology examination

Methods include routine examination, serological examination, joint fluid examination, X-ray plain film examination and arthroscopy, etc.
, and the following laboratory indicators are commonly used in laboratories:

Erythrocyte sedimentation rate (ESR)

Also known as erythrocyte sedimentation rate, ESR increases when the condition of rheumatism patients is active, but increased ESR does not mean rheumatism
.
ESR can decrease with the remission of rheumatism, and can be used as one of the
indicators of drug efficacy.
ESR is not a specific indicator of disease activity, and sometimes ESR is not consistent
with disease activity.

Rheumatoid factor (RF)

RF is of great significance for the diagnosis of rheumatoid arthritis, with a positive rate of 60%~80%.

RF positive
for rheumatic diseases such as systemic lupus erythematosus, Sjogren's syndrome, vasculitis, etc.
Chronic infectious diseases such as bacterial endocarditis, tuberculosis, etc.
RF can also be positive
.

However, RF is not a specific indicator of rheumatoid arthritis, RF negative does not exclude the diagnosis of rheumatoid arthritis, and RF positive does not equal rheumatoid arthritis, for example, in normal elderly people about 5% positive rate
.

C-reactive protein (CRP)

C-reactive protein is one of the inflammatory proteins, and it is closely related to
the condition when the disease is active in rheumatism.
Other inflammations, such as infection or trauma, are markedly elevated
in C-reactive protein.

Antistreptolysin O

Antistreptolysin O, also known as anti-O, an increase in antistreptolysin O indicates a recent hemolytic streptococcal infection, which is helpful for the diagnosis of rheumatism and can be further confirmed
by the age of the patient and other clinical manifestations.
Hyperlipidemia, macroglobulinemia, etc.
can also be found to be antistreptolysin
O.

In some hospitals, the complete set of rheumatism is a combination of routine blood tests, which generally include the above four items: rheumatoid factor, C-reactive protein, ESR, and antistreptolysin
.
Test results are definitively diagnostic for rheumatism and rheumatoid disease
.

Associated antibodies

HLA-B27 is used as a genetic marker, and more than 90% of patients with ankylosing spondylitis (AS) are HLA-B27 positive
.
However, it should be noted that a positive HLA-B27 does not mean that the patient has ankylosing spondylitis
.
A positive HLA-B27 alone does not diagnose AS, and a negative HLA-B27 does not exclude AS
.

Antinuclear antibodies (ANAs) are the initial screening test for rheumatic diseases and are extremely important
for the diagnosis of rheumatism.
Therefore, most rheumatic patients can be positive for ANA, such as 90%~98% positive patients with systemic lupus
erythematosus.
However, positive ANA can also occur in a small number of normal people (especially the elderly), chronic infections, liver disease, and use of certain drugs
.
In clinical practice, although the symptoms are relieved during treatment, ANA is always positive or the titer does not decrease, in fact, ANA is not related to disease fluctuations, and ANA positive or high titer does not mean that the disease is serious
.

Anti-extractable nuclear antigen antibodies (ENA antibodies) include autoantibodies such as anti-Sm, RNP, SSA, SSB, Scl-70, jo-1 and anti-ribosomal antibodies, and are mainly used for the diagnosis and differential diagnosis of autoimmune rheumatism such as systemic lupus erythematosus (SLE), subacute cutaneous lupus (SCLE), mixed connective tissue disease (MCTR), scleroderma (SSc), Sjogren syndrome (SS) and polymyositis/dermatomyositis (PM/DM).

。 Thereinto:

Anti-Sm is an iconic antibody for lupus erythematosus;

Anti-RNP can appear in the serum of patients such as MCTD, SLE, SSc, etc.
;

A positive anti-SSA may indicate SS or SCLE;

Anti-SSB is the signature antibody of SS;

Anti-jo-1 is the hallmark antibody of PM/DM;

Anti-Scl-70 is the signature antibody of SSc;

A positive antiribosomal antibody suggests SLE
.

Patients should remember that although positive for an antibody may indicate a disease, it is not absolute, and that clinical diagnosis is more important based on clinical presentation
.

Anti-DNA double-stranded antibodies (anti-dsDNA) are also specific antibodies for systemic lupus erythematosus (SLE), but diagnosis still needs to be made in conjunction with clinical findings
.

Anticardiolipin antibody (ACL) is an important autoantibody in anticardiolipin syndrome, and positive ACL often indicates a predisposition to arteriovenous thrombosis, and the incidence of cerebrovascular accidents is as high as 56%.

Anticardiolipin antibodies are closely related to SLE, and patients with SLE with positive ACL are prone to thrombosis, thrombocytopenic purpura, secondary anemia and other symptoms
.
Women with positive anticardiolipin antibodies are prone to recurrent miscarriage
.
However, due to the limitations of testing techniques, ACLs can be false-positive, and certain diseases such as infection can also lead to temporary elevation
of ACLs.

Complement tests include CH50, C4, C3, and B factors, and decreased complement levels in SLE generally indicate SLE activity, while elevated complement often indicates infection
.

Anti-neutrophil cytoplasmic antibody (ANCA) is a serum marker of systemic necrotizing vasculitis, which is valuable for the differential diagnosis and prognosis estimation of vasculitic disease, and is an important indicator of
disease activity.
ANCA titers are elevated
at the time of onset (relapse).
ANCA can present two types of antibodies: (1) cytoplasmic (c-ANCA) or PR3-ANCA: mainly associated with Wegener's granulomatous vasculitis; (2) Perinuclear type (P-ANCA) or MPO-ANCA can be produced
in patients with churg-Strass syndrome and ulcerative colitis.