Altered blood-based biomarkers in carpal tunnel syndrome. A systematic review and meta-analysis.
Jorge Menéndez-Cámara, Miguel Molina-Álvarez, Jesús Zabala-Zambrano and 6 others
CTS patients have higher blood levels of inflammatory and fibrosis-related markers than healthy controls, but the evidence is low to very low certainty.
These are indirect systemic signals, not yet a tool for diagnosis or treatment decisions.
Key findings
1Proinflammatory markers (SMD 0.63, moderate effect) and anti-inflammatory markers (SMD 1.0, large effect) are both significantly elevated in CTS patients compared to healthy controls, with low certainty of evidence.
2Fibrosis-related markers show a large significant increase (SMD 1.64) with moderate certainty, while white blood cell counts, cardiovascular markers, and oxidative stress markers show no significant overall differences between CTS patients and controls.
3Vitamin D is significantly lower in CTS patients (SMD -0.73, very low certainty), but in three of the five included studies the healthy control groups also had levels below the hypovitaminosis threshold.
Still to come
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
All included studies are observational (cross-sectional or cohort), so causality cannot be established. It is unknown whether the blood changes cause CTS, result from it, or share a common cause. Certainty of evidence is low to very low in six of the nine meta-analyses. Heterogeneity is high in most analyses (I-squared values above 75% in several), meaning the true effect varies substantially between studies. Blood measurements are indirect surrogates. They do not necessarily reflect what is happening at the median nerve itself. Disease duration was inconsistently reported across studies, preventing analysis of how biomarkers change over time. No standardized adjustment for confounders such as BMI, medications, or comorbidities. Seven of the 28 studies did not report the laboratory technique used. The authors did not search grey literature. Pooling different molecules under one category (for example, all proinflammatory cytokines together) assumes they behave similarly, which may not be the case.
Declared interests
Annina B Schmid reports a Wellcome Trust Clinical Career Development Fellowship (222101/Z/20/Z) that includes funding grants. All other authors declare no competing interests. No company that manufactures a CTS treatment funded, designed, or wrote the study.
The easy way to misread this
Do not read the elevated inflammatory and fibrosis markers as a blood test for diagnosing CTS or as a predictor of which treatment will work. The evidence is low to very low certainty, the measurements are indirect (blood, not the nerve), and the authors call these hypothesis-generating signals, not clinical tools.
Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →