Summary
| Direction in Major Depressive Disorder | ↑ Elevated — higher than in the comparison group |
|---|---|
| Category | Inflammatory |
| Compared against | females with depression vs healthy female controls |
| Test type | Blood test (serum / plasma / whole blood) |
| LOINC code | 26881-5 |
| Source | Jarkas et al. 2024 — doi:10.1016/j.bbi.2024.07.037 |
| Condition atlas | Major Depressive Disorder Biomarker Atlas |
Other conditions where Interleukin-6 (IL-6) is reported
- Interleukin-6 (IL-6) in Gulf War Illness — ↑ elevated vs HGV
- Interleukin-6 (IL-6) in Long COVID — ↑ elevated vs HC, R
- IL-6 in Low Back Pain — ↑ elevated vs chronic nonspecific LBP vs asymptomatic controls
- Interleukin-6 (IL-6) in Lyme Disease — ↑ elevated vs HC
- Interleukin-6 (IL-6) in ME/CFS — ↕ inconsistent vs HC
- IL-6 in PACVS — ↑ elevated vs HC
- IL-6 in Rheumatoid Arthritis — ↑ elevated vs RA vs healthy (established inflammatory pathway/drug target)
See the cross-condition hub: Interleukin-6 (IL-6) across conditions.
Related Inflammatory markers in Major Depressive Disorder
- CRP ↑
Full list: Major Depressive Disorder Biomarker Atlas.
Frequently asked questions
Is IL-6 high or low in Major Depressive Disorder?
Elevated. Studies summarised in the OSMF atlas report higher IL-6 in Major Depressive Disorder than in the reference group of the cited comparison (females with depression vs healthy female controls). Source: Jarkas et al. 2024.
Which test measures IL-6?
It is measured as a blood test (serum / plasma / whole blood). The standard laboratory code is LOINC 26881-5. Many of the cited studies used research-grade assays, so clinical availability may vary.
Is one abnormal IL-6 result diagnostic of Major Depressive Disorder?
No. No single biomarker is diagnostic of Major Depressive Disorder. IL-6 findings come from group comparisons, overlap considerably between patients and controls, and vary with study design, timing and comparison group. A result should be interpreted by a clinician alongside symptoms, history and other tests.
Is IL-6 specific to Major Depressive Disorder?
No. The same marker is also reported in Gulf War Illness, Long COVID, Low Back Pain, Lyme Disease, ME/CFS, PACVS, Rheumatoid Arthritis in this atlas, so it reflects shared biology (for example inflammation or vascular stress) rather than a condition-specific signature.
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Last reviewed: 2026-07-03 · Page generated from major-depressive-disorder.json · Browse: Major Depressive Disorder atlas · Biomarker Index · All marker pages
Disclaimer: This page is an educational synthesis of published, peer-reviewed research and is not medical advice. Biomarker findings vary across studies with case definitions, comparison groups, timing and assay methods. Direction of change reflects the predominant finding in the cited source and does not establish a diagnostic threshold. Discuss any test result with a qualified clinician.