Time courses of changes of para-, meta-, and ortho-tyrosine in septic patients: A pilot study

Szélig, Lívia and Kun, Szilárd and Woth, Gábor László and Molnár, Gergő Attila and Zrínyi, Zita and Kátai, Emese and Lantos, János and Wittmann, István and Bogár, Lajos and Miseta, Attila János and Csontos, Csaba (2016) Time courses of changes of para-, meta-, and ortho-tyrosine in septic patients: A pilot study. REDOX REPORT, 21 (4). pp. 180-189. ISSN 1351-0002

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Abstract

Objectives Sepsis is associated with oxidative stress. Due to oxidative stress, three tyrosine isoforms, para-, meta-, and ortho-tyrosine (p-, m-, and o-Tyr), can be formed non-enzymatically in smaller amounts. p-Tyr is mainly formed physiologically in the kidneys through the activity of the phenylalanine hydroxylase enzyme. The three tyrosine isoforms may undergo different renal handling. Methods Twenty septic patients were involved in the study and 25 healthy individuals served as controls. Blood and urine levels of p-, m-, and o-Tyr were measured on admission and four consecutive days. Results Serum m-Tyr levels were higher in septic patients than in controls on days 2 (P = 0.031) and 3 (P = 0.035). Serum p-Tyr levels were lower in the cases than in controls on days 1 (P = 0.005) and 2 (P = 0.040), and subsequently normalized due to a day-by-day elevation (P = 0.002). The tendency of urinary m-Tyr concentration was decreasing (P = 0.041), while that of urinary p-Tyr concentration was increasing (P = 0.001). Fractional excretion of m-Tyr (FEm-Tyr) showed a decreasing tendency (P = 0.009), and was, on all days, higher than FEp-Tyr, which remained near-normal, less than 4%. Procalcitonin showed significant correlation with FEm-Tyr (r = 0.454; P < 0.001). Discussion Our data suggest that the oxidative stress marker m-Tyr and physiologic p-Tyr may be handled differently in septic patients. The excretion of m-Tyr correlates with inflammation. m-Tyr may be actively secreted or produced in the kidney in some patients, whereas the decreased serum level of p-Tyr is a consequence of diminished renal production and not of renal loss.

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