Taenzer, Maja, Löffler-Ragg, Judith, Schroll, Andrea et al. · International journal of tryptophan research : IJTR · 2023 · DOI
This study examined urine samples from people with Long COVID and ME/CFS to look for chemical imbalances that might explain their symptoms. Researchers found that both groups had lower levels of certain amino acids and neurotransmitters (brain chemicals) compared to healthy people, particularly affecting energy production, mood, and sleep. These chemical signatures could potentially be used as simple urine tests to help doctors understand what is happening in patients and create personalized treatments.
Finding measurable biomarkers in urine is crucial for ME/CFS patients because routine blood tests often appear normal despite significant illness. These results suggest that urine metabolite analysis could provide an accessible, objective way to identify underlying biological mechanisms and potentially guide personalized treatment decisions for both Long COVID and ME/CFS.
This pilot study does not prove that these metabolite changes cause ME/CFS or Long COVID symptoms—it only shows associations in a small sample. The cross-sectional design cannot establish whether metabolite abnormalities precede symptoms, result from them, or are consequences of illness behavior. Larger longitudinal studies are needed to determine causality and whether correcting these metabolites improves symptoms.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Taenzer, Maja, Löffler-Ragg, Judith, Schroll, Andrea, Monfort-Lanzas, Pablo, Engl, Sabine, Weiss, Günter, et al. (2023). Urine Metabolite Analysis to Identify Pathomechanisms of Long COVID: A Pilot Study.. International journal of tryptophan research : IJTR. https://doi.org/10.1177/11786469231220781
BibTeX
@article{mecfsatlas-taenzer-2023-urine-metabolite,
author = {Taenzer, Maja and Löffler-Ragg, Judith and Schroll, Andrea and Monfort-Lanzas, Pablo and Engl, Sabine and Weiss, Günter and Brigo, Natascha and Kurz, Katharina},
title = {Urine Metabolite Analysis to Identify Pathomechanisms of Long COVID: A Pilot Study.},
journal = {International journal of tryptophan research : IJTR},
year = {2023},
doi = {10.1177/11786469231220781},
note = {PubMed: 38144169},
url = {https://www.mecfsatlas.com/evidence/taenzer-2023-urine-metabolite},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-27. https://www.mecfsatlas.com/evidence/taenzer-2023-urine-metabolite
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