Summary
| Direction in Long COVID | ↑ Elevated — higher than in the comparison group |
|---|---|
| Category | Coagulation |
| Also described as | Plasminogen activator inhibitor-1 |
| Compared against | HC (healthy controls) |
| Associated symptoms | Impaired fibrinolysis |
| Test type | Blood test (serum / plasma / whole blood) |
| LOINC code | 3242-4 |
| Source | Thomas et al. 2024 — doi:10.1007/s40291-024-00731-z |
| Condition atlas | Long COVID Biomarker Atlas |
Trials, interventions and tests
Commercial test availability
PAI-1 (Plasminogen Activator Inhibitor) — specialty laboratory test.
Links are for reference only; availability, specimen requirements and coverage vary by location.
Related Coagulation markers in Long COVID
- Fibrinogen ↑
- Amyloid-fibrin microclots ↑
- D-dimer ↑
- Platelet hyperactivation ↑
- Thrombin-antithrombin complex ↑
Full list: Long COVID Biomarker Atlas.
Frequently asked questions
Is PAI-1 high or low in Long COVID?
Elevated. Studies summarised in the OSMF atlas report higher PAI-1 in Long COVID than in healthy controls. Source: Thomas et al. 2024.
What symptoms is PAI-1 associated with in Long COVID?
The cited literature associates this marker with Impaired fibrinolysis. These are population-level associations and do not mean the marker causes the symptoms.
Which test measures PAI-1?
It is measured as a blood test (serum / plasma / whole blood). The standard laboratory code is LOINC 3242-4. Commercial laboratories such as LabCorp list an orderable assay.
Is one abnormal PAI-1 result diagnostic of Long COVID?
No. No single biomarker is diagnostic of Long COVID. PAI-1 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.