Plasma protein thiolation index (PTI) as a potential biomarker for left ventricular hypertrophy in humans

BACKGROUND: Left ventricular hypertrophy (LVH) has been associated with oxidative stress, although not with the protein thiolation index (PTI). This study explored the potential use of PTI as a biomarker of oxidative stress in patients with LVH. METHODS: We recruited 70 consecutive patients (n = 35 LVH and n = 35 non-LVH) based on an echocardiography study in our institution (left ventricular mass indexed to body surface area). Plasma levels of both S-thiolated protein and total thiols were measured as biomarkers of oxidative stress by spectrophotometry, and PTI was calculated as the molar ratio between S-thiolated proteins and the total thiol concentration. RESULTS: Values for plasma S-thiolated proteins were higher in patients with LVH than in the control group (P = 0.01). There were no differences in total thiols between the LVH group and the control group. Finally, PTI was higher in patients with LVH than in the control group (P = 0.001). The area under the ROC curve was 0.75 (95% CI, 0.63-0.86; P<0.001), sensitivity was 70.6%, and specificity was 68.6%, thus suggesting that PTI could be used to screen for LVH. A multivariable logistic regression model showed a positive association (P = 0.02) between PTI and LVH (OR = 1.24 [95% CI, 1.03-1.49]) independently of gender (OR = 3.39 [95% CI, 0.60-18.91]), age (OR = 1.03 [95% CI, 0.96-1.10]), smoking (OR = 5.15 [95% CI, 0.51-51.44]), glucose (OR = 0.99 [95% CI, 0.97-1.01]), systolic arterial pressure (OR = 1.10 [CI 1.03-1.17]), diastolic arterial pressure (OR = 0.94 [CI 0.87-1.02]), dyslipidemia (OR = 1.46 [95% CI, 0.25-8.55]), estimated glomerular filtration rate (OR = 0.98 [95% CI, 0.96-1.01]), body mass index (OR = 1.03 [95% CI, 0.90-1.10]), and valvular and/or coronary disease (OR = 5.27 [95% CI, 1.02-27.21]). CONCLUSIONS: The present study suggests that PTI could be a new biomarker of oxidative stress in patients with LVH.