Summary
| Direction in Major Depressive Disorder | ↑ Elevated — higher than in the comparison group |
|---|---|
| Category | Endocrine |
| Compared against | non-suicidal MDD patients |
| Associated symptoms | suicidal behavior |
| Source | Messaoud et al. 2022 — doi:10.2174/1568026621666210909160210 |
| Condition atlas | Major Depressive Disorder Biomarker Atlas |
Related Endocrine markers in Major Depressive Disorder
- Cortisol ↑
Full list: Major Depressive Disorder Biomarker Atlas.
Frequently asked questions
Is Kynurenine/Tryptophan Ratio high or low in Major Depressive Disorder?
Elevated. Studies summarised in the OSMF atlas report higher Kynurenine/Tryptophan Ratio in Major Depressive Disorder than in non-suicidal MDD patients. Source: Messaoud et al. 2022.
What symptoms is Kynurenine/Tryptophan Ratio associated with in Major Depressive Disorder?
The cited literature associates this marker with suicidal behavior. These are population-level associations and do not mean the marker causes the symptoms.
Which test measures Kynurenine/Tryptophan Ratio?
The atlas record does not list a standardised clinical test code (LOINC) for Kynurenine/Tryptophan Ratio, which usually means it was measured with research assays or study-specific protocols rather than a routine clinical panel. Check the cited source for the exact method.
Is one abnormal Kynurenine/Tryptophan Ratio result diagnostic of Major Depressive Disorder?
No. No single biomarker is diagnostic of Major Depressive Disorder. Kynurenine/Tryptophan Ratio 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.
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Last reviewed: 2026-10-08 · 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.