{
  "slug": "long-covid",
  "id": "long-covid-biomarkers",
  "condition": {
    "name": "Long COVID",
    "shortName": "Long COVID",
    "alternateNames": [
      "PASC",
      "Post-Acute Sequelae of COVID-19"
    ]
  },
  "page": {
    "title": "Long COVID Biomarker Atlas | PASC Blood Tests & Metabolite Alterations",
    "breadcrumbName": "Long COVID Biomarkers",
    "description": "Searchable atlas of long COVID (PASC) biomarkers — cytokines, metabolomics, coagulation, vascular, neurological, and proteomic alterations vs healthy and recovered individuals, from peer-reviewed systematic reviews.",
    "keywords": [
      "long COVID biomarkers",
      "PASC biomarkers",
      "post-acute COVID syndrome blood tests",
      "long COVID cytokines",
      "long COVID metabolomics",
      "D-dimer long COVID",
      "microclots long COVID",
      "post-acute sequelae of COVID-19 blood tests",
      "long COVID blood work",
      "IL-6 long COVID",
      "brain fog biomarkers",
      "long COVID immune exhaustion",
      "ceramides long COVID",
      "autoantibodies long COVID",
      "complement activation PASC",
      "biomarker atlas",
      "biomarker database",
      "peer-reviewed biomarkers",
      "chronic illness biomarkers"
    ],
    "canonical": "https://research.opensourcemed.info/long-covid-biomarkers.html",
    "hero": "Molecular, metabolic, and immunological alterations reported in post-acute sequelae of COVID-19 (PASC / long COVID) compared to healthy controls and fully recovered individuals.",
    "dateModified": "2026-06-29"
  },
  "categories": {
    "inflammatory": "Inflammatory",
    "metabolic": "Metabolic",
    "coagulation": "Coagulation",
    "vascular": "Vascular",
    "neurological": "Neurological",
    "immune": "Immune",
    "proteomic": "Proteomic",
    "lipidomic": "Lipidomic",
    "microbiome": "Microbiome",
    "viral": "Viral"
  },
  "filters": [
    "inflammatory",
    "metabolic",
    "coagulation",
    "vascular",
    "neurological",
    "immune",
    "lipidomic",
    "proteomic",
    "microbiome"
  ],
  "markers": [
    {
      "name": "Interleukin-6 (IL-6)",
      "alternateName": "Pro-inflammatory cytokine",
      "direction": "up",
      "category": "inflammatory",
      "comparison": "HC, R",
      "symptoms": "Fatigue, systemic inflammation",
      "reference": {
        "citation": "Lai et al. 2023",
        "doi": "10.3389/fmed.2023.1085988"
      },
      "testType": "BloodTest",
      "loinc": "26881-5"
    },
    {
      "name": "Tumor Necrosis Factor-α (TNF-α)",
      "alternateName": "Pro-inflammatory cytokine",
      "direction": "up",
      "category": "inflammatory",
      "comparison": "HC, R",
      "symptoms": "Fatigue, myalgia",
      "reference": {
        "citation": "Lai et al. 2023; Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest",
      "loinc": "3074-8"
    },
    {
      "name": "Interleukin-1α (IL-1α)",
      "alternateName": "Pro-inflammatory cytokine",
      "direction": "up",
      "category": "inflammatory",
      "comparison": "HC, R",
      "symptoms": "Systemic inflammation",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest",
      "loinc": "26864-3"
    },
    {
      "name": "C-Reactive Protein (CRP)",
      "alternateName": "Acute phase protein",
      "direction": "up",
      "category": "inflammatory",
      "comparison": "HC, R",
      "symptoms": "General inflammation marker",
      "reference": {
        "citation": "Lai et al. 2023",
        "doi": "10.3389/fmed.2023.1085988"
      },
      "testType": "BloodTest",
      "loinc": "1988-5"
    },
    {
      "name": "Soluble CD14 (sCD14)",
      "alternateName": "Monocyte activation marker",
      "direction": "up",
      "category": "inflammatory",
      "comparison": "HC, R",
      "symptoms": "Innate immune activation",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest",
      "loinc": "30180-5"
    },
    {
      "name": "Flt-1 / sVEGFR-1",
      "alternateName": "Soluble VEGF receptor",
      "direction": "up",
      "category": "inflammatory",
      "comparison": "HC, R",
      "symptoms": "Vascular inflammation",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "CCL4 (MIP-1β)",
      "alternateName": "Chemokine",
      "direction": "up",
      "category": "inflammatory",
      "comparison": "Non-COVID controls",
      "symptoms": "Elevated at 3 months post-infection",
      "reference": {
        "citation": "Kallaste et al. 2025",
        "doi": "10.3390/medicina61060996"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Cystatin D (CST5)",
      "alternateName": "Protease inhibitor",
      "direction": "up",
      "category": "inflammatory",
      "comparison": "Non-COVID controls",
      "symptoms": "Elevated at 6 months post-infection",
      "reference": {
        "citation": "Kallaste et al. 2025",
        "doi": "10.3390/medicina61060996"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Pro-inflammatory cytokines (composite)",
      "alternateName": "IL-1β, IL-8, IFN-γ, etc.",
      "direction": "down",
      "category": "inflammatory",
      "comparison": "R (at 6 months)",
      "symptoms": "Immune exhaustion pattern",
      "reference": {
        "citation": "Kallaste et al. 2025",
        "doi": "10.3390/medicina61060996"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Transforming Growth Factor-β (TGF-β)",
      "alternateName": "Fibrotic cytokine",
      "direction": "up",
      "category": "inflammatory",
      "comparison": "HC, R",
      "symptoms": "Pulmonary symptoms",
      "reference": {
        "citation": "Lai et al. 2023",
        "doi": "10.3389/fmed.2023.1085988"
      },
      "testType": "BloodTest",
      "loinc": "27999-4"
    },
    {
      "name": "Interleukin-8 (IL-8)",
      "alternateName": "CXCL8",
      "direction": "up",
      "category": "inflammatory",
      "comparison": "HC",
      "symptoms": "Neutrophil chemotaxis",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "BloodTest",
      "loinc": "26998-9"
    },
    {
      "name": "Interleukin-10 (IL-10)",
      "alternateName": "Anti-inflammatory cytokine",
      "direction": "mixed",
      "category": "inflammatory",
      "comparison": "HC, R",
      "symptoms": "Immune regulation",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "BloodTest",
      "loinc": "26862-5"
    },
    {
      "name": "Ferritin",
      "alternateName": "Acute phase reactant",
      "direction": "mixed",
      "category": "inflammatory",
      "comparison": "HC",
      "symptoms": "Iron metabolism dysregulation",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "BloodTest",
      "loinc": "2276-4"
    },
    {
      "name": "Serum Amyloid A (SAA)",
      "alternateName": "Acute phase protein",
      "direction": "up",
      "category": "inflammatory",
      "comparison": "HC",
      "symptoms": "Systemic inflammation",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest",
      "loinc": "35648-5"
    },
    {
      "name": "ATP (plasma)",
      "alternateName": "Adenosine triphosphate",
      "direction": "down",
      "category": "metabolic",
      "comparison": "HC, R",
      "symptoms": "Fatigue, energy deficit",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Serine",
      "alternateName": "Amino acid",
      "direction": "down",
      "category": "metabolic",
      "comparison": "HC, R",
      "symptoms": "Fatigue, depression, cognitive dysfunction",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Sarcosine",
      "alternateName": "Methylglycine",
      "direction": "down",
      "category": "metabolic",
      "comparison": "HC, R",
      "symptoms": "Depression, anxiety, brain fog",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Aspartate",
      "alternateName": "Amino acid",
      "direction": "down",
      "category": "metabolic",
      "comparison": "HC, R",
      "symptoms": "Amino acid metabolism impairment",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Asparagine",
      "alternateName": "Amino acid",
      "direction": "down",
      "category": "metabolic",
      "comparison": "R",
      "symptoms": "Nitrogen metabolism",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Glutamine",
      "alternateName": "Amino acid",
      "direction": "down",
      "category": "metabolic",
      "comparison": "HC, R",
      "symptoms": "Immune-metabolic coupling",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Arginine",
      "alternateName": "Amino acid",
      "direction": "down",
      "category": "metabolic",
      "comparison": "HC",
      "symptoms": "NO pathway, immune function",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Histidine",
      "alternateName": "Amino acid",
      "direction": "down",
      "category": "metabolic",
      "comparison": "R",
      "symptoms": "Amino acid metabolism",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "TCA cycle intermediates",
      "alternateName": "Succinate, citrate, etc.",
      "direction": "up",
      "category": "metabolic",
      "comparison": "R (fully recovered)",
      "symptoms": "Mitochondrial dysfunction",
      "reference": {
        "citation": "Pérez-Mazliah et al. 2024",
        "doi": "10.1021/acs.jproteome.3c00706"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Kynurenine",
      "alternateName": "Tryptophan metabolite",
      "direction": "up",
      "category": "metabolic",
      "comparison": "HC",
      "symptoms": "Neuroinflammation, fatigue",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "5-Hydroxykynurenine",
      "alternateName": "Kynurenine pathway",
      "direction": "up",
      "category": "metabolic",
      "comparison": "HC",
      "symptoms": "Neurotoxic metabolite pathway",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Serotonin",
      "alternateName": "5-HT",
      "direction": "up",
      "category": "metabolic",
      "comparison": "HC",
      "symptoms": "Mood, GI symptoms",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Putrescine",
      "alternateName": "Polyamine",
      "direction": "up",
      "category": "metabolic",
      "comparison": "HC",
      "symptoms": "Polyamine metabolism",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "5-Aminolevulinate",
      "alternateName": "Heme precursor",
      "direction": "up",
      "category": "metabolic",
      "comparison": "HC",
      "symptoms": "Porphyrin/heme pathway",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Porphobilinogen",
      "alternateName": "Porphyrin precursor",
      "direction": "up",
      "category": "metabolic",
      "comparison": "HC, R",
      "symptoms": "Heme biosynthesis disruption",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Uracil",
      "alternateName": "Pyrimidine",
      "direction": "down",
      "category": "metabolic",
      "comparison": "HC",
      "symptoms": "Nucleotide metabolism",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Thymine",
      "alternateName": "Pyrimidine",
      "direction": "down",
      "category": "metabolic",
      "comparison": "HC",
      "symptoms": "Nucleotide metabolism",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Xanthine",
      "alternateName": "Purine metabolite",
      "direction": "up",
      "category": "metabolic",
      "comparison": "HC",
      "symptoms": "Purine catabolism",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "4-Aminobutanoate (GABA)",
      "alternateName": "Inhibitory neurotransmitter precursor",
      "direction": "up",
      "category": "metabolic",
      "comparison": "R",
      "symptoms": "Neurotransmitter metabolism",
      "reference": {
        "citation": "Saito et al. 2024",
        "doi": "10.3389/fimmu.2024.1341843"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Lactate",
      "alternateName": "Anaerobic metabolite",
      "direction": "up",
      "category": "metabolic",
      "comparison": "HC",
      "symptoms": "Exercise intolerance, PEM",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest",
      "loinc": "2524-7"
    },
    {
      "name": "Carnitine / Acylcarnitines",
      "alternateName": "Fatty acid transport",
      "direction": "mixed",
      "category": "metabolic",
      "comparison": "HC, R",
      "symptoms": "Mitochondrial fatty acid oxidation",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Ceramides",
      "alternateName": "Sphingolipids",
      "direction": "down",
      "category": "lipidomic",
      "comparison": "R (fully recovered)",
      "symptoms": "Mitochondrial dysfunction, membrane integrity",
      "reference": {
        "citation": "Pérez-Mazliah et al. 2024",
        "doi": "10.1021/acs.jproteome.3c00706"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Sphingolipid species",
      "alternateName": "447 lipids profiled",
      "direction": "mixed",
      "category": "lipidomic",
      "comparison": "R",
      "symptoms": "Lipidomic discrimination of LC",
      "reference": {
        "citation": "Pérez-Mazliah et al. 2024",
        "doi": "10.1021/acs.jproteome.3c00706"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Phosphatidylcholines",
      "alternateName": "Membrane phospholipids",
      "direction": "mixed",
      "category": "lipidomic",
      "comparison": "HC",
      "symptoms": "Membrane remodeling",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Lysophosphatidylcholines",
      "alternateName": "LPC",
      "direction": "mixed",
      "category": "lipidomic",
      "comparison": "HC",
      "symptoms": "Inflammatory lipid mediators",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "D-dimer",
      "alternateName": "Fibrin degradation product",
      "direction": "up",
      "category": "coagulation",
      "comparison": "HC, R",
      "symptoms": "Coagulopathy, thrombotic risk",
      "reference": {
        "citation": "Lai et al. 2023; Thomas et al. 2024",
        "doi": "10.3389/fmed.2023.1085988"
      },
      "testType": "BloodTest",
      "loinc": "48065-7"
    },
    {
      "name": "Fibrinogen",
      "alternateName": "Clotting factor",
      "direction": "up",
      "category": "coagulation",
      "comparison": "HC",
      "symptoms": "Coagulation activation",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "BloodTest",
      "loinc": "3255-7"
    },
    {
      "name": "PAI-1",
      "alternateName": "Plasminogen activator inhibitor-1",
      "direction": "up",
      "category": "coagulation",
      "comparison": "HC",
      "symptoms": "Impaired fibrinolysis",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "BloodTest",
      "loinc": "3242-4"
    },
    {
      "name": "Amyloid-fibrin microclots",
      "alternateName": "Fibrin(ogen) amyloid deposits",
      "direction": "up",
      "category": "coagulation",
      "comparison": "HC",
      "symptoms": "Microvascular occlusion, hypoperfusion",
      "reference": {
        "citation": "Pretorius et al. 2023",
        "doi": "10.1186/s12933-023-01931-4"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Platelet hyperactivation",
      "alternateName": "P-selectin, GP IIb/IIIa",
      "direction": "up",
      "category": "coagulation",
      "comparison": "HC",
      "symptoms": "Thromboinflammation",
      "reference": {
        "citation": "Pretorius et al. 2023",
        "doi": "10.1186/s12933-023-01931-4"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Thrombin-antithrombin complex",
      "alternateName": "TAT",
      "direction": "up",
      "category": "coagulation",
      "comparison": "HC",
      "symptoms": "Coagulation cascade activation",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "BloodTest"
    },
    {
      "name": "von Willebrand Factor (vWF)",
      "alternateName": "Endothelial marker",
      "direction": "up",
      "category": "vascular",
      "comparison": "HC",
      "symptoms": "Endothelial injury",
      "reference": {
        "citation": "Lai et al. 2023",
        "doi": "10.3389/fmed.2023.1085988"
      },
      "testType": "BloodTest",
      "loinc": "27816-0"
    },
    {
      "name": "ICAM-1",
      "alternateName": "Intercellular adhesion molecule",
      "direction": "up",
      "category": "vascular",
      "comparison": "HC",
      "symptoms": "Endothelial activation",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "BloodTest"
    },
    {
      "name": "VCAM-1",
      "alternateName": "Vascular adhesion molecule",
      "direction": "up",
      "category": "vascular",
      "comparison": "HC",
      "symptoms": "Vascular inflammation",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Resistin",
      "alternateName": "Adipokine",
      "direction": "up",
      "category": "vascular",
      "comparison": "HC",
      "symptoms": "Insulin resistance, inflammation",
      "reference": {
        "citation": "Lai et al. 2023",
        "doi": "10.3389/fmed.2023.1085988"
      },
      "testType": "BloodTest",
      "loinc": "42702-4"
    },
    {
      "name": "Endothelin-1",
      "alternateName": "Vasoactive peptide",
      "direction": "up",
      "category": "vascular",
      "comparison": "HC",
      "symptoms": "Vasoconstriction, POTS",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "BloodTest",
      "loinc": "27940-8"
    },
    {
      "name": "Asymmetric dimethylarginine (ADMA)",
      "alternateName": "NO synthase inhibitor",
      "direction": "up",
      "category": "vascular",
      "comparison": "HC",
      "symptoms": "Reduced NO bioavailability",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "BloodTest",
      "loinc": "10988-1"
    },
    {
      "name": "Neurofilament light chain (NfL)",
      "alternateName": "Axonal damage marker",
      "direction": "up",
      "category": "neurological",
      "comparison": "HC",
      "symptoms": "Neurological LC, brain fog",
      "reference": {
        "citation": "Lai et al. 2023",
        "doi": "10.3389/fmed.2023.1085988"
      },
      "testType": "BloodTest",
      "loinc": "94635-5"
    },
    {
      "name": "GFAP",
      "alternateName": "Glial fibrillary acidic protein",
      "direction": "up",
      "category": "neurological",
      "comparison": "HC",
      "symptoms": "Neurological LC, astrocyte activation",
      "reference": {
        "citation": "Lai et al. 2023",
        "doi": "10.3389/fmed.2023.1085988"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Tau protein",
      "alternateName": "Neurodegeneration marker",
      "direction": "up",
      "category": "neurological",
      "comparison": "HC",
      "symptoms": "Cognitive dysfunction",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "S100B",
      "alternateName": "Astrocyte protein",
      "direction": "up",
      "category": "neurological",
      "comparison": "HC",
      "symptoms": "Blood-brain barrier disruption",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Anti-IFN-α autoantibodies",
      "alternateName": "Type I IFN autoAbs",
      "direction": "up",
      "category": "immune",
      "comparison": "HC",
      "symptoms": "Immune dysregulation",
      "reference": {
        "citation": "Wilhelm et al. 2026",
        "doi": "10.1016/S1473-3099(25)00411-6"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Anti-IFN-ω autoantibodies",
      "alternateName": "Type I IFN autoAbs",
      "direction": "up",
      "category": "immune",
      "comparison": "HC",
      "symptoms": "Impaired antiviral immunity",
      "reference": {
        "citation": "Wilhelm et al. 2026",
        "doi": "10.1016/S1473-3099(25)00411-6"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Anti-GPCR autoantibodies",
      "alternateName": "G-protein coupled receptor Abs",
      "direction": "up",
      "category": "immune",
      "comparison": "HC",
      "symptoms": "Dysautonomia, POTS",
      "reference": {
        "citation": "Wilhelm et al. 2026",
        "doi": "10.1016/S1473-3099(25)00411-6"
      },
      "testType": "BloodTest"
    },
    {
      "name": "β2-microglobulin",
      "alternateName": "MHC class I component",
      "direction": "up",
      "category": "immune",
      "comparison": "HC",
      "symptoms": "Immune activation",
      "reference": {
        "citation": "Kallaste et al. 2025",
        "doi": "10.3390/medicina61060996"
      },
      "testType": "BloodTest",
      "loinc": "1952-1"
    },
    {
      "name": "Complement C3a / C5a",
      "alternateName": "Anaphylatoxins",
      "direction": "up",
      "category": "immune",
      "comparison": "HC",
      "symptoms": "Complement activation",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "T cell exhaustion markers",
      "alternateName": "PD-1, TIM-3, LAG-3",
      "direction": "up",
      "category": "immune",
      "comparison": "HC",
      "symptoms": "T cell dysfunction",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Low naive T cells / High effector memory",
      "alternateName": "T cell subset shift",
      "direction": "mixed",
      "category": "immune",
      "comparison": "HC",
      "symptoms": "Immune repertoire alteration",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Complement cascade proteins",
      "alternateName": "C3, C4, factor B",
      "direction": "up",
      "category": "proteomic",
      "comparison": "HC",
      "symptoms": "Complement-mediated inflammation",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Coagulation cascade proteins",
      "alternateName": "Factor X, thrombin, etc.",
      "direction": "up",
      "category": "proteomic",
      "comparison": "HC",
      "symptoms": "Thromboinflammation",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Acute phase proteins",
      "alternateName": "AGP, haptoglobin, orosomucoid",
      "direction": "up",
      "category": "proteomic",
      "comparison": "HC",
      "symptoms": "Systemic inflammation",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "ECM remodeling proteins",
      "alternateName": "MMPs, TIMPs, collagen fragments",
      "direction": "mixed",
      "category": "proteomic",
      "comparison": "HC",
      "symptoms": "Tissue remodeling",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Cortisol",
      "alternateName": "Glucocorticoid",
      "direction": "mixed",
      "category": "proteomic",
      "comparison": "HC",
      "symptoms": "HPA axis dysregulation",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest",
      "loinc": "2143-6"
    },
    {
      "name": "SARS-CoV-2 spike protein",
      "alternateName": "Circulating spike antigen",
      "direction": "mixed",
      "category": "viral",
      "comparison": "HC",
      "symptoms": "Antigen persistence hypothesis",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "MedicalTest"
    },
    {
      "name": "SARS-CoV-2 RNA",
      "alternateName": "Viral RNAemia",
      "direction": "mixed",
      "category": "viral",
      "comparison": "HC",
      "symptoms": "Viral reservoir hypothesis",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "MedicalTest"
    },
    {
      "name": "Gut microbiome alpha diversity",
      "alternateName": "Shannon index",
      "direction": "down",
      "category": "microbiome",
      "comparison": "HC",
      "symptoms": "GI symptoms, dysbiosis",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Faecalibacterium prausnitzii",
      "alternateName": "Commensal bacterium",
      "direction": "down",
      "category": "microbiome",
      "comparison": "HC",
      "symptoms": "Butyrate production deficit",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Short-chain fatty acids (SCFAs)",
      "alternateName": "Butyrate, propionate, acetate",
      "direction": "mixed",
      "category": "microbiome",
      "comparison": "HC",
      "symptoms": "GI and metabolic symptoms",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "Opportunistic pathogens",
      "alternateName": "Candida, Enterobacteriaceae",
      "direction": "up",
      "category": "microbiome",
      "comparison": "HC",
      "symptoms": "Dysbiosis",
      "reference": {
        "citation": "Baalbaki et al. 2025",
        "doi": "10.1111/all.16526"
      },
      "testType": "BloodTest"
    },
    {
      "name": "LDH (Lactate dehydrogenase)",
      "alternateName": "Tissue damage marker",
      "direction": "up",
      "category": "metabolic",
      "comparison": "HC",
      "symptoms": "Tissue injury",
      "reference": {
        "citation": "Kallaste et al. 2025",
        "doi": "10.3390/medicina61060996"
      },
      "testType": "BloodTest",
      "loinc": "2532-0"
    },
    {
      "name": "Vitamin D (25-OH)",
      "alternateName": "Calcidiol",
      "direction": "mixed",
      "category": "metabolic",
      "comparison": "HC",
      "symptoms": "Immune modulation",
      "reference": {
        "citation": "Kallaste et al. 2025",
        "doi": "10.3390/medicina61060996"
      },
      "testType": "BloodTest",
      "loinc": "1989-3"
    },
    {
      "name": "NT-proBNP",
      "alternateName": "Natriuretic peptide",
      "direction": "up",
      "category": "vascular",
      "comparison": "HC",
      "symptoms": "Cardiovascular LC",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "BloodTest",
      "loinc": "33762-6"
    },
    {
      "name": "Troponin",
      "alternateName": "Cardiac injury marker",
      "direction": "up",
      "category": "vascular",
      "comparison": "HC",
      "symptoms": "Cardiac involvement",
      "reference": {
        "citation": "Thomas et al. 2024",
        "doi": "10.1007/s40291-024-00731-z"
      },
      "testType": "BloodTest",
      "loinc": "10839-9"
    }
  ]
}