Summary
| Direction in Long COVID | ↑ Elevated — higher than in the comparison group |
|---|---|
| Category | Immune |
| Also described as | MHC class I component |
| Compared against | HC (healthy controls) |
| Associated symptoms | Immune activation |
| Test type | Blood test (serum / plasma / whole blood) |
| LOINC code | 1952-1 |
| Source | Kallaste et al. 2025 — doi:10.3390/medicina61060996 |
| Condition atlas | Long COVID Biomarker Atlas |
Trials, interventions and tests
Commercial test availability
β2-microglobulin — commercial laboratory test.
Links are for reference only; availability, specimen requirements and coverage vary by location.
Related Immune markers in Long COVID
- Anti-GPCR autoantibodies ↑
- Complement C3a / C5a ↑
- Anti-IFN-ω autoantibodies ↑
- T cell exhaustion markers ↑
- Anti-IFN-α autoantibodies ↑
- Low naive T cells / High effector memory ↕
Full list: Long COVID Biomarker Atlas.
Frequently asked questions
Is β2-microglobulin high or low in Long COVID?
Elevated. Studies summarised in the OSMF atlas report higher β2-microglobulin in Long COVID than in healthy controls. Source: Kallaste et al. 2025.
What symptoms is β2-microglobulin associated with in Long COVID?
The cited literature associates this marker with Immune activation. These are population-level associations and do not mean the marker causes the symptoms.
Which test measures β2-microglobulin?
It is measured as a blood test (serum / plasma / whole blood). The standard laboratory code is LOINC 1952-1. Commercial laboratories such as Quest Diagnostics, LabCorp list an orderable assay.
Is one abnormal β2-microglobulin result diagnostic of Long COVID?
No. No single biomarker is diagnostic of Long COVID. β2-microglobulin 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: 2026-06-29 · Page generated from long-covid.json · Browse: Long COVID 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.