Rheumatology lab tests for individual laboratory tests should be performed depending on the symptoms present and the suspected disease. Performing the entire “panel” of research is, in many cases, unjustified. Some of them only need to be performed once in a lifetime, while others are used to assess disease activity and are therefore repeated from time to time. The tests that are most often ordered in rheumatology practice are discussed below.

Inflammation studies

• Increase (acceleration) of ESR– remember that this is a non-specific indicator (it also occurs in many other conditions, such as anemia, pregnancy, infections, cancer, after strenuous exercise, trauma and surgery). In rheumatology, it is often used to monitor disease activity.
• Increase in CRP levels– like ESR is a non-specific marker of inflammation. A very large increase in CRP concentration raises the suspicion of an acute bacterial infection. It is used to monitor disease activity.
• Abnormalities in blood counts– often we are dealing with moderate anemia (large and rapidly increasing anemia requires urgent medical attention) and an increase in the number of platelets. Some systemic connective tissue diseases include abnormal white blood cell counts, anemia and a reduced number of platelets.
• Deviations in the proteinogram (quantitative and qualitative test of blood proteins)– this test allows you to detect increased levels of proteins involved in the inflammatory reaction and distinguish acute inflammation from chronic.

The correct result of the above tests speaks against inflammatory joint disease, although it does not exclude it. If an incorrect result is obtained, further diagnosis is necessary to look for the cause of the inflammation (rheumatological disease or other disease). Blood for testing should be drawn on an empty stomach, avoiding previous heavy physical exertion.

Disease-specific studies

RF (rheumatoid factor)– increased concentration of RF is found in most patients with rheumatoid arthritis (very high levels indicate high activity of the disease and predict its more severe course). However, RF can also appear in other diseases as well as in healthy people (especially in old age).

Determination of the titer of anti-CCP antibodies (antibodies against cyclic citrullinated peptide)– is a very useful test in the diagnosis of rheumatoid arthritis. Contrary to RF, increased anti-CCP titer is found almost exclusively in RA patients, and it occurs early in the disease.

Autoantibodiesare antibodies against various components of the body’s own cells, and are found in autoimmune diseases.

• Determination of ANA antibodies (antinuclear antibodies)is performed when systemic connective tissue disease (so-called collagenosis) is suspected. At the beginning, the ANA 1 test is performed, i.e. a screening test to find out if the antibodies are present and what type of light they have under the microscope (e.g. homogeneous, granular, peripheral). If the ANA 1 result is positive, further tests (ANA 2 and ANA3) are performed to determine the exact type and titer of the antibodies. Some types of antibodies indicate the presence of certain diseases, for example:
  • anti-dsDNA and anti-Sm forsystemic lupus erythematosus
  • anti-SS-A (Ro)-forSjögren’s syndrome, systemic lupus erythematosus, neonatal lupus
  • anti-SS-B (La)-for Sjögren’s syndrome, systemic lupus erythematosus
  • anti-Scl-70-for systemic scleroderma
  • anti-RNP-for mixed connective tissue disease
  • anti-Jo-1—for polymyositis
  • anti-Mi-2 for dermatomyositis
  • antihistones for drug-induced lupus and systemic lupus erythematosus. It should be noted that a “weak positive” ANA result can also occur in healthy people and is not a disease in itself. A negative ANA result, especially if it recurs after some time, is often sufficient to rule out systemic connective tissue disease.erythematosus.
• ANCA (antibodies against the cytoplasm of neutrophils)-indicates systemic vasculitis. -indicates
• aPl (antiphospholipid antibodies)-occur in the so-called antiphospholipid syndrome, associated with an increased risk of thromboembolic and obstetric complications (e.g. recurrent miscarriage). These include anti-cardiolipin antibodies, anti-ß2-glycoprotein-1, and lupus anticoagulant. Antiphospholipid syndrome is often associated with systemic lupus; in this disease, aPl should be measured, especially in women planning pregnancy, before the use of anti-ß2-glycoprotein-1,-occurestrogens(e.g. in hormone replacement therapy or contraceptives), and also before surgery.

The concentrations of complement components (mainly C3c, C4)– are measured in order to control the activity of systemic lupus erythematosus (their reduction indicates an increase in disease activity).

HLA-B27– is a genetic marker of a group of diseases, the so-called seronegative spondyloarthritis (including ankylosing spondylitis and psoriatic arthritis). This test is performed once in a lifetime. HLA-B27 is positive in about 8% of the population, of which only some people have the disease; Thus, it does not immediately mean an illness, just as a negative result does not exclude it. The HLA-B27 test is useful in patients with uncertain diagnosis who have symptoms of the disease – a positive test result makes the diagnosis highly probable.

Uric acid levels are measured whengoutis suspected . Usually, there is a significant increase in its concentration (hyperuricemia). However, it should be remembered that during an acute attack of gout, the uric acidconcentration may be normal (therefore, it is usually necessary to repeat the determinations). By itself, hyperuricemia is not yet a disease – only one in five people with elevated uric acid develops gout.

Other research

The doctor may also recommend other tests, e.g. for Lyme disease and other infections, determination of the levels of thyroid hormones,prolactinand vitamin D (depending on the symptoms present and the suspected disease).

Drug safety monitoring

Drug safety monitoring is a very important element of safe treatment, especially in the case of rheumatic diseases, in which drugs are taken for a long time and sometimes in high doses. Depending on the therapy used, various tests are performed; basic are:

• blood count
• Liver function assessment (usually ALT)
• assessment of kidney function (creatinine).