title: Diurnal variation of biopyrrin excretion in random urine specimens is not corrected by creatinine.
abstract: Circulating bilirubin is thought to function as a physiological antioxidant. One of the decomposition products of this process is the biopyrrins, which include two regioisomers: biotripyrrin-a (1,14,15,17-tetrahydro-2,7,13-trimethyl-1,14-deoxy-3-vinyl-16H-tripyrrin-8,12-dipropionic acid) and biotripyrrin-b (1,14,15,17-tetrahydro-3,7,13-trimethyl-1,14-deoxy-3-vinyl-16H-tripyrrin-8,12-dipropionic acid). We measured biopyrrins in random urine specimens and investigated whether the biopyrrin values obtained were valid when expressed as a ratio of the creatinine (Cr) concentrations. All of the random urine specimens collected over 48 hr were from presumably healthy adults. We measured the biopyrrins by means of an enzyme-linked immunosorbent assay (ELISA) using an anti-bilirubin monoclonal antibody. When the values were expressed in terms of the ratio to Cr, the within-day coefficient of variation (%CV) of the excretion of biopyrrins was reduced to 27%+/-10% (P<0.05) from 59%+/-27%. However, assay values on random or spot urine specimens were unreliable because of the large %CV. The biopyrrin concentrations only in the first-morning-urine specimens in terms of both absolute amounts and ratios to Cr significantly reflected those in a 24-hr urine specimen (P<0.001). Concentrations in a random urine specimen voided at the second collection or later did not correlate with the concentration in a 24-hr urine specimen (P>0.05), even if their values were corrected by Cr. The amounts of biopyrrins excreted in 24-hr urine specimens were significantly correlated with the 24-hr cortisol excretion (P<0.001) but not to uropepsin (P>0.05).
authors.affiliation: Department of Laboratory Medicine, Toho University Ohashi Medical Center, Meguro, Tokyo, Japan. ihara@med.toho-u.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ihara
authors.forename: Takayuki
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Morita
authors.forename: Akiko
authors.initials: A
authors.lastname: Hirano
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Okada
authors.forename: Naotaka
authors.initials: N
authors.lastname: Hashizume
authors.forename: Izuru
authors.initials: I
authors.lastname: Shioji
authors.forename: Hajime
authors.initials: H
authors.lastname: Yoshimura
mesh_terms: D000328:Adult; D000368:Aged; D002940:Circadian Rhythm; D003404:Creatinine / Q000652:urine*; D005260:Female; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D011758:Pyrroles / Q000652:urine*
chemical_list: D011758:Pyrroles; C099842:biotripyrrin a; C099843:biotripyrrin b; D003404:Creatinine