During pregnancy the alterations of kynurenine and tryptophan metabolism play an important role in local signalling and the prevention of fetal rejection. The aim was to investigate urinary levels of kynurenine and tryptophan during physiological pregnancy, and to determine their stability in urine during sample storage at different conditions. Urinary samples were obtained from 73 healthy pregnant women (median age 31 years), during the 1st, 2nd, and 3rd trimesters and from 42 healthy non-pregnant women (median age 30 years). Liquid chromatography methods using selective and sensitive mass spectrometry detection were used for analysis. Urinary neopterin, kynurenine, and tryptophan increased during the pregnancy and in comparison to the non-pregnant women. No correlation of the analytes with gestation age within each trimester and among the different analytes was observed. Kynurenine and tryptophan were stable in urine for 14 days at 4 °C, 6 months at - 22 °C, and 12 months at - 84 °C. Present results demonstrate differences in urinary concentrations of kynurenine, tryptophan, and neopterin between women with physiological pregnancy and healthy women. Simultaneous determination of kynurenine, tryptophan and neopterin may be explored in the disorders of pregnancy in future investigations.

Department of Analytical Chemistry Faculty of Pharmacy in Hradec Králové Charles University Akademika Heyrovského 1203 8 500 05 Hradec Králové Czech Republic

Department of Clinical Biochemistry and Diagnostics University Hospital Hradec Králové Sokolská 581 500 05 Hradec Králové Czech Republic

Department of Obstetrics and Gynecology University Hospital Olomouc 1 P Pavlova 6 779 00 Olomouc Czech Republic

Department of Oncology Faculty of Medicine and Dentistry Palacký University Olomouc 1 P Pavlova 6 779 00 Olomouc Czech Republic

Gynecology Clinics Hradec Králové Malé náměstí 7 500 03 Hradec Králové Czech Republic

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