Uncommon Urinary Excretion Pattern of Bile Acids in Healthy Humans: Identification and Determination of 7β-Hydroxylated Bile Acid Series

Nobuo Yamaga, Hiromi Kohara* and Atsushi Sagayama†

Department of Biochemistry, *Second Department of Internal Medicine and †Department of Pathological Biochemistry, Faculty of Medicine, Tottori University, Yonago 683, Japan

Urinary bile acids of three volunteers without hepatobiliary diseases were analyzed using capillary column gas chromatography and gas chromatography-mass spectrometry. In addition to the usual bile acids generally detected in the urine of healthy humans, the following bile acids, so-called "unusual bile acids", were also identified: 3β,7β-dihydroxycholanoic acid, 3α,7β,12(α-trihydroxycholanoic acid and norcholic acid. In two of the three volunteers, 7β-hydroxylated bile acids, which are ursodeoxycholic acid, 3β,7β-dihydroxycholanoic acid and 3α,7β,12α-trihydroxycholanoic acid, constituted 21% and 30% of the total urinary bile acids, respectively, while in the other, they constituted about 70-88%, unexpectedly. These findings suggest that 7β-hydroxylated bile acids are present in a considerable amount even in healthy humans.

Key words: 3β,7β-dihydroxycholanoic acid; healthy humans;7β-hydroxylated bileacids;urine; usual bile acids

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