29/01/2026
F2-Isoprostanes (8-iso-PGF₂α):
F2-isoprostanes are prostaglandin-like compounds formed in vivo by free-radical peroxidation of arachidonic acid. Measurement of 8-iso-prostaglandin F₂α (8-iso-PGF₂α, also called 8-iso-P or F2-IsoP) is widely regarded as the best current biomarker of lipid peroxidation and systemic oxidative stress.
Why this matters:
• Mechanistic relevance. F2-IsoPs reflect true in-vivo free-radical damage to membrane lipids, not just downstream inflammation, and therefore provide mechanistic information that routine inflammatory markers do not capture.
• Clinical associations. Elevated F2-IsoP levels have been linked to cardiovascular disease, diabetes, obesity, smoking, and critical illness — useful for risk stratification, exposure assessment, and translational studies.
Analytical reality:
• Reference methods. Isotope-dilution GC-MS was the original reference method; modern isotope-dilution LC-MS/MS workflows now deliver high sensitivity, specificity and throughput for plasma and urine. Always use isotope-labelled internal standards and validated cleanup (SPE/TLC) to avoid artifactual formation or ion suppression.
• Free vs total. Decide whether you need native (free) F2-IsoP or total F2-IsoP (after enzymatic/saponification hydrolysis to release conjugates) and validate the hydrolysis step when total is measured. Report which form you measure.
Pre-analytic essentials:
• Specimen choice. Urine is convenient and integrates exposure over time; plasma provides closer temporal resolution for acute changes. For urine, normalize to creatinine for concentration differences.
• Prevent artefacts. Lipid peroxides form ex vivo if samples are mishandled. Add antioxidants in extraction buffers where method requires, process promptly, keep samples cold, aliquot quickly and store at −80 °C. Avoid hemolysis.
• Controls and blanks. Include extraction blanks, isotope internal standards, and pooled QC samples in every batch to detect artefactual oxidation and monitor analytical drift.
Practical lab roadmap:
Define intended use: population research (urine) vs acute kinetics or translational pilot (plasma).
Implement a validated MS-based method (isotope-dilution LC-MS/MS or GC-MS), establish LoD/LoQ, linearity, precision, recovery and matrix effects.
Lock pre-analytic SOPs: tube and anticoagulant, time-to-centrifuge, recommended additives (antioxidant), aliquot sizes, −80 °C storage, and allowable freeze–thaw cycles.
Run method comparison with a reference lab and participate in inter-lab comparisons where possible.
Report specimen type, whether value is free or total F2-IsoP, method (GC-MS or LC-MS/MS) and an interpretive line (for example: “Elevated urinary 8-iso-PGF₂α/creatinine suggests increased lipid peroxidation/oxidative stress — correlate clinically.”).
Pitfalls to warn clinicians about:
• TBARS and simple colorimetric assays are nonspecific and prone to artefacts — avoid relying on them for research or clinical claims.
• Method heterogeneity: numbers from different platforms or between free vs total measurements are not directly comparable without mapping/harmonization.
• Pre-analytic lapses create false positives — bad handling kills signal integrity faster than you think.
Summary: If you want a reliable, biologically meaningful measure of in-vivo lipid peroxidation, F2-isoprostanes (8-iso-PGF₂α) measured by isotope-dilution MS with strict pre-analytics and QC are the gold standard. Use urine for population studies and plasma for acute kinetics, normalize urine to creatinine, and always report method and specimen so clinicians interpret results correctly.
Has your lab measured 8-iso-PGF₂α or total F2-isoprostanes? Which specimen and MS workflow did you use, and what was the biggest pre-analytic headache? One short tip, please.
