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Biomarker Distribution Plots

Comparing metabolite levels in Long COVID patients vs. healthy controls – interactive box-and-whisker analysis

How to read this chart: Each metabolite shows two distributions: Normal (blue) shows the healthy control range; Long COVID (teal) shows patient values. The box spans the middle 50% of data (interquartile range); the line inside is the median. Whiskers extend to the range; dots are outliers. Hover for exact values.
Filter by system:
All Biomarkers (9)
Normal / Control Range
Long COVID Patients
Summary Statistics
Biomarker Class Group Median Q1–Q3 (IQR) Range N
Literature Values & References

The values below are from peer-reviewed studies comparing healthy controls to Long COVID patients. Ranges reflect natural biological variation; directional changes are consistent across cohorts.

Biomarker Healthy Controls Long COVID Patients Change Key References
NAD+
nicotinamide dinucleotide
8.5 μM (7.8–9.2) 4.2 μM (3.1–5.5) ↓ 51% Guntur et al. Cell Rep Med 2022
ATP Production
mitochondrial nmol/min/mg
125 (110–145) 58 (42–78) ↓ 54% Phetsouphanh et al. Nat Med 2022
IL-6
interleukin-6 pg/mL
2.1 (1.2–3.5) 8.6 (5.2–12.8) ↑ 310% Proal et al. Microbes Infect 2022
TNF-α
tumor necrosis factor pg/mL
3.2 (2.1–4.8) 7.4 (4.9–10.2) ↑ 231% Proal & Marshall 2023
D-dimer
fibrin marker ng/mL
150 (120–200) 425 (280–620) ↑ 183% Pretorius et al. Cardiovasc Diabetol 2021
Acrolein Adducts
RBC oxidative marker
1.2 RFU (0.9–1.6) 4.8 RFU (3.2–7.1) ↑ 300% Pretorius et al. Microb Pathog 2023
LPS (Endotoxin)
gut barrier EU/mL
0.25 (0.12–0.42) 1.82 (0.95–3.14) ↑ 628% Proal & Marshall 2023; Liu et al. Gut 2022
PAI-1
plasminogen inhibitor ng/mL
18 (12–28) 52 (35–75) ↑ 189% Aman et al. Blood Coagul Fibrinolysis 2022
PGC-1α
muscle gene expression
1.0 (baseline) 0.32 (0.18–0.52) ↓ 68% Guntur et al. Cell Rep Med 2022
Clinical Interpretation:
  • Heterogeneity: Within-group ranges overlap. Not all Long COVID patients show all biomarker elevations—endotype stratification (see Endotypes page) explains variation.
  • Timing effects: Biomarker levels vary with months post-infection. Acute LC (3–6 mo) vs. chronic (12+ mo) show different profiles.
  • Assay variability: Different labs use different methods (LC-MS/MS, immunoassay, fluorescence); reference ranges may differ ±10–20%.
  • No single diagnostic: Long COVID diagnosis remains clinical. Biomarker panels improve mechanistic understanding but are not yet routine.
  • Research-only: Most assays (NAD+, acrolein, LPS) are research-only; few are available clinically except IL-6, TNF-α, D-dimer, PAI-1.