Total plasma antioxidant capacity in cystic fibrosis

Several studies have demonstrated ongoing oxidative stress in cystic fibros is (CF). With the complexity of the antioxidant network, measurement of ind ividual antioxidants does not necessarily assess how they work in combinati on. One measure that has been proposed as a gauge of total plasma antioxida nt capacity is the Trolox-equivalent antioxidant capacity (TEAC) of plasma. We decided to look at plasma TEAC levels in children with CF, and relate t his measure to their nutritional status, lung function, and blood measureme nts of several known antioxidants. We hypothesized that values in general w ould be lower than healthy control values, especially during acute pulmonar y exacerbations. Twenty-nine children were evaluated, five of whom were dur ing an acute pulmonary exacerbation. Height and weight, expiratory spiromet ry, and lung volumes were assessed, as were serum concentrations of vitamin s A and E, uric acid, albumin, and lymphocyte glutathione (GSH) concentrati ons. TEAC values for nonhospitalized patients (1.40 +/- 0.20 mmol/L) were not di fferent from laboratory control values (1.35 +/- 0.11 mmol/L), but greater than values for hospitalized patients (1.09 +/- 0.17 mmol/L). TEAC correlat ed with anthropometric values (height: r = 0.39, P < 0.03; weight: r = 0.50 , P < 0.01; body mass index: r = 0.47, P < 0.01), and pulmonary function (f orced expiratory volume in 1 sec: r = 0.43, P < 0.02; residual volume/total lung capacity: r = -0.42, P < 0.03), but not with age. Univariate correlat ion with blood measurements demonstrated a significant correlation of TEAC with uric acid (r = 0.49, P < 0.02), but not with albumin, vitamins A or E, or lymphocyte GSH. Multiple regression analysis demonstrated a correlation between TEAC and uric acid, albumin, and lymphocyte GSH in the non-hospita lized group (r(2) = 0.38, P < 0.03). We conclude that TEAC appears to represent a mixed antioxidant response, ra ther than response to a single antioxidant. While being responsive to oxida tive stress, the mechanism of the response may differ between clinical situ ations, such that the clinical significance of changes in plasma TEAC remai ns to be defined. Pediatr Pulmonol. 2000; 29:81-87, (C) 2000 Wiley-Liss, In c.