Interleukin-6 (IL-6) in chronic inflammation and rheumatoid arthritis
According to a 2014 review, interleukin-6 (IL-6) is a soluble messenger substance that affects inflammation, immune reactions and the production of blood cells. According to that review, the body normally produces IL-6 promptly and briefly, in an infection or tissue damage.
According to the review, in various immune diseases, including rheumatoid arthritis, the production of IL-6 continues dysregulated, and that plays a disease-causing role in chronic inflammation and autoimmunity. Only a blood test shows how high IL-6 is.
Star-SHL uses a reference value of 0 to 10 pg/ml for IL-6.
Doctor's Assessment Included
Interleukin-6 (IL-6) is a messenger substance that, according to a 2014 review, the body produces promptly in infections and tissue damage, and that makes the liver produce inflammation proteins such as CRP.
- Star-SHL uses a reference value of 0 to 10 pg/ml for IL-6, Unilabs a reference value below 7.0 ng/l.
- According to the 2014 review, dysregulated, continual production of IL-6 plays a role in chronic inflammation and autoimmunity, such as rheumatoid arthritis.
- According to Unilabs, IL-6 is not very stable: the sample has to be kept cool or frozen quickly after centrifuging.
Interleukin-6 (IL-6): what Dutch laboratories use
There is no nationally agreed reference value; this is what individual laboratories publish.
| Laboratory | Group | Reference value (ng/l) | Relative scale |
|---|---|---|---|
| Star-shl | · Everyone | 0–10 pg/ml pg/ml | |
| Unilabs | · Everyone · a limit, not a range | < 7 ng/l |
7
|
Source: Star-shl
Source: Unilabs
Each value as the laboratory itself publishes it, retrieved in 2026.
Interleukin-6 (IL-6): what this test measures
An IL-6 test measures the concentration of interleukin-6 in the serum, in pg/ml at Star-SHL. According to the 2014 review, IL-6 makes the liver produce serum amyloid A (SAA) and CRP, among other proteins.
Interleukin-6 (IL-6): why this value matters
IL-6 matters in chronic inflammation: according to an earlier study cited by the 2014 review, IL-6 induces the production of hepcidin, a substance that blocks iron transport in the gut. According to the review, the IL-6 and hepcidin axis is responsible for the low iron levels and the anaemia associated with chronic inflammation.
Interleukin-6 (IL-6): how the blood test works
- Referral
- No GP referral needed. After the order we arrange the referral through ZorgDomein, within one business day; orders after 17:00 or at the weekend start on the next business day. ZorgDomein emails a barcode, and that barcode is what the draw site needs.
- The draw
- A blood draw from a vein in the arm, at a partner laboratory's draw site. No home kit, no finger prick.
- Where
- 650+ draw sites run by independent laboratories across the Netherlands. Draw sites
Interleukin-6 (IL-6): when is testing worthwhile?
The sources read for this page give no indication of when an IL-6 test is requested in rheumatoid arthritis or another chronic inflammation.
Interleukin-6 (IL-6): symptoms of a high or low value
Low Levels
For a low IL-6, within the Star-SHL range of 0 to 10 pg/ml, the sources read name no cause.
High Levels
According to the 2014 review, a raised IL-6 can be linked to dysregulated, continual production in chronic inflammation and autoimmunity, or to an infection or tissue damage.
Interleukin-6 (IL-6): causes of a low or high value
What raises the value
-
Infection
IL-6 is produced promptly and transiently in response to infections; it is generated at the site of the infection and sends a warning signal to the entire body.
-
Tissue damage, as in burns or trauma
IL-6 also issues a warning signal in tissue damage, as in non-infectious inflammation after burns or trauma.
-
Chronic inflammatory and autoimmune diseases, such as rheumatoid arthritis
In various immune diseases, such as rheumatoid arthritis, the production of IL-6 continues dysregulated.
-
Surgery
An earlier study cited by the review saw blood IL-6 rise during sterile operations before body temperature and acute-phase proteins.
Interleukin-6 (IL-6): lifestyle and this value
Discuss a raised IL-6 in rheumatoid arthritis or another chronic inflammation with your GP or rheumatologist.
Interleukin-6 (IL-6): frequently asked questions
What is tocilizumab?
According to a 2014 review, tocilizumab is an antibody against the IL-6 receptor, which after clinical trials was approved for the treatment of rheumatoid arthritis and juvenile idiopathic arthritis.
Interleukin-6 (IL-6): sources
- Star-shl, Labbepalingen (referentiewaarden per bepaling), star-shl.nl, geraadpleegd 2026-10-01 (retrieved 2026) star-shl.nl
- Unilabs, Bepalingenklapper (referentiewaarden per bepaling), bepalingenklapper.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenklapper.nl
- Tanaka T, Narazaki M, Kishimoto T. IL-6 in Inflammation, Immunity, and Disease. Cold Spring Harb Perspect Biol. 2014;6(10):a016295, geraadpleegd 2026-10-17 (retrieved 2026) pmc.ncbi.nlm.nih.gov
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Interleukin-6 (IL-6)
€228,-