Quantification of urinary 8-iso-PGF2alpha using liquid chromatography-tandem mass spectrometry and association with elevated troponin levels

Clin Biochem. 2007 Nov;40(16-17):1297-304. doi: 10.1016/j.clinbiochem.2007.07.023. Epub 2007 Aug 17.

Abstract

Objectives: Increased lipid peroxidation (i.e. "oxidative stress") has been identified as a central mechanism in the development of atherosclerosis and inflammatory vascular damage. Measurement of 8-iso-PGF(2alpha) has demonstrated to be a reliable indicator of in vivo oxidative stress levels. The purpose of this study was to develop a rapid, sensitive, and specific LC-MS/MS method for detection of urinary 8-iso-PGF(2alpha), establish reference intervals, and correlate isoprostane levels with cardiac troponin I.

Design and methods: Urinary 8-iso-PGF(2alpha) was detected after direct injection onto a C18 silica column and monitored in the MRM mode using m/z transitions of 353.2>193.25 (8-iso-PGF(2alpha)) and 357.2>197.25 (8-iso-PGF(2alpha)-d(4)). The LC-MS/MS method was also compared to an ELISA kit. Reference interval studies were evaluated against a separate population of patients presenting with chest pain that had positive cTnI values.

Results: Elution of 8-iso-PGF(2alpha) was achieved after 7 min, with a total run time of 10 min. Inter-assay CVs were 13.8-20.0% and intra-assay CVs were 10.9-17.0%. Linearity ranged from 100 pg/mL to 100 ng/mL. Deming regression of ELISA and LC-MS/MS methods for 8-iso-PGF(2alpha) levels yielded poor correlation, with a slope of 0.0265, y-intercept of 0.255 ng/mL, and R(2) value of 0.0434. Urine 8-iso-PGF(2alpha) concentrations in samples obtained from healthy individuals (n=34) ranged from 57 to 390 ng/g creatinine with a mean of 221 ng/g creatinine. 8-iso-PGF(2alpha) levels were statistically significant in troponin-positive (n=35) versus troponin-negative (n=36) patients (p<0.0049).

Conclusions: This LC-MS/MS method provides a rapid, accurate, sensitive, and cost-effective alternative to other methods for detection of 8-iso-PGF(2alpha) in urine. 8-iso-PGF(2alpha) has potential to be a great prognostic risk indicator in individuals with a high probability for future coronary events.

MeSH terms

  • Chromatography, Liquid / methods*
  • Creatinine / analysis
  • Dinoprost / analogs & derivatives*
  • Dinoprost / urine
  • Enzyme-Linked Immunosorbent Assay
  • Humans
  • Lipid Peroxidation
  • Oxidative Stress
  • Reproducibility of Results
  • Tandem Mass Spectrometry / methods*
  • Troponin / analysis*

Substances

  • Troponin
  • 8-epi-prostaglandin F2alpha
  • Creatinine
  • Dinoprost