Skip to main content
Your session has expired. Reloading...
Inflammation

Interleukin-6 (IL-6): from the site of inflammation to the liver, and the cytokine storm

According to a 2014 review, interleukin-6 (IL-6) is a signalling substance of the immune system, made at the site of inflammation in its initial stage and then travelling through the blood to the liver. According to that review, in the liver IL-6 rapidly starts the production of acute-phase proteins such as CRP and fibrinogen, proteins that rise in inflammation.

According to the review, during a so-called cytokine storm, a potentially fatal immune reaction, a major boost in IL-6 production is observed. Only a blood test shows whether IL-6 is raised.

Star-SHL uses 0 to 10 pg/ml for IL-6 and Unilabs below 7.0 ng/l.

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.

Reference ranges by group, in ng/l
Star-shl · Everyone 0–10 pg/ml
Unilabs · Everyone · a limit, not a range < 7 ng/l
7
0 7.7 ng/l

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 determines the amount of interleukin-6 in the serum: Star-SHL in pg/ml, with ELISA, and Unilabs in ng/l. The C-reactive protein (CRP) that IL-6 sets off in the liver is a separate blood value.

Interleukin-6 (IL-6): why this value matters

IL-6 matters because, according to the 2014 review, it reaches the bone marrow and promotes the maturation of megakaryocytes there, the cells that release platelets. According to the review, changes in acute-phase proteins and in red blood cell and platelet counts are used in the laboratory to evaluate the severity of 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 Dutch laboratory guides of Star-SHL and Unilabs do not describe when an IL-6 test is requested, and the NVKC has no page on IL-6.

Interleukin-6 (IL-6): symptoms of a high or low value

Low Levels

An IL-6 within 0 to 10 pg/ml (Star-SHL) or below 7.0 ng/l (Unilabs) is not raised, and the sources read name no cause of a low IL-6.

High Levels

According to the 2014 review, a major boost in IL-6 production is seen in a cytokine storm, a potentially fatal immune reaction; a high IL-6 can also fit the early stage of inflammation, according to the review.

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

Take a high IL-6 result to your GP, who can check whether an infection, tissue damage or chronic inflammation is involved.

Interleukin-6 (IL-6): frequently asked questions

What is a cytokine storm?

According to a 2014 review, a cytokine storm is a potentially fatal immune reaction caused by hyperactivation of T cells, a type of white blood cell, in which a major boost in IL-6 production is observed.

Interleukin-6 (IL-6): sources

  1. Star-shl, Labbepalingen (referentiewaarden per bepaling), star-shl.nl, geraadpleegd 2026-10-01 (retrieved 2026) star-shl.nl
  2. Unilabs, Bepalingenklapper (referentiewaarden per bepaling), bepalingenklapper.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenklapper.nl
  3. 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

Tests with related values

These panels measure values from the same category as this marker.

Testosterone

Complete Men's Health Panel

A broad men's health panel: hormones, heart, metabolic, and organ function in one blood draw.

HbA1c (Glycated Hemoglobin) ALT (Alanine Aminotransferase) TSH (Thyroid Stimulating Hormone) Triglycerides Creatinine Glucose (Fasting) Free T4 (Thyroxine) LDL Cholesterol SHBG (Sex Hormone Binding Globulin) Total Cholesterol Vitamin D (25-OH) Free Testosterone Total Testosterone Ferritin hs-CRP (High Sensitivity CRP) HDL Cholesterol eGFR (Estimated Glomerular Filtration Rate) Cholesterol/HDL Ratio Non-HDL Cholesterol LDL/HDL Ratio
€289,-
Prostate

Men Over 40 Panel

Age-appropriate screening including testosterone and PSA.

HbA1c (Glycated Hemoglobin) PSA (Prostate-Specific Antigen) ALT (Alanine Aminotransferase) TSH (Thyroid Stimulating Hormone) Triglycerides Creatinine Free T4 (Thyroxine) LDL Cholesterol SHBG (Sex Hormone Binding Globulin) Total Cholesterol Vitamin D (25-OH) Free Testosterone Total Testosterone hs-CRP (High Sensitivity CRP) HDL Cholesterol eGFR (Estimated Glomerular Filtration Rate) Cholesterol/HDL Ratio Non-HDL Cholesterol LDL/HDL Ratio
€279,-

Medical reviewer

Medical standards

Dr. Naimi oversees the medical standards behind our content and assessments.

Medical policy
CIBG Ministerie van Volksgezondheid,
Welzijn en Sport Official BIG registration BIG 49928676701 Opens in a new tab

Interleukin-6 (IL-6)

€228,-