Urinary Excretion of an Isomer of Bilirubin during Phototherapy

Knox, Isabella; Ennever, John F.; Speck, William T.

doi:10.1203/00006450-198502000-00010

Cited by 26 publications

(17 citation statements)

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“…[Note that in Fig. 1 a the peak areas do not reflect the relative concentrations of the bilirubin isomers, because of different molar extinction coefficients at 465 nm (21).] However, lumirubin is cleared from the serum more rapidly than is the configurational isomer.…”

Section: Discussionmentioning

confidence: 99%

“…However, serial sampling at 15-20 min intervals for 180 min from 14 individual fetuses (91-139 days) showed that TSH was secreted in a markedly exaggerated pulsatile manner compared to that observed after birth. The mean amplitude of TSH pulses fell (p < 0.005) from 5.9 2 8.1 pU/ml in the fetuses to 2.1 + 1.1 pU/ml in five neonatal lambs (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) days) and to 1.5 f 0.4 pU/ml in three adult nonpregnant ewes. The mean pulse frequency for the 14 fetuses was 0.7 + 0.3 pulses/h and was reduced (p < 0.001) to 0.3 + 0.1 pulseslh in lambs and to 0.3 f 0.1 pulses/h in the ewes.…”

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confidence: 99%

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Phototherapy for Neonatal Jaundice: in Vivo Clearance of Bilirubin Photoproducts

et al. 1985

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ABSTRACT. Phototherapy results in the conversion of native bilirubin to more water-soluble configurational and structural isomers. The serum half-life for the configurational isomer, the principal photoproduct in vivo, was determined by high pressure liquid chromatography in six premature infants following cessation of phototherapy. The mean half-life for this isomer was 15 h. The excretion of this isomer, calculated from the measured half-life, is less than half of daily bilirubin production, and therefore cannot account for the total bilirubin elimination observed during phototherapy. The serum concentration of the structural isomer, lumirubin, is lower than that of the configurational isomer; however, excretion is more rapid (serum half-life < 2 h). Because of its rapid excretion, lumirubin may be an important pathway for bilirubin elimination during phototherapy. (Pediatr Res 19: 205-208, 1985) Abbreviation HPLC, high pressure liquid chromatography Despite the widespread use of phototherapy in the treatment of neonatal hyperbilirubinemia (l), the detailed mechanism by which visible light affects bilirubin metabolism in jaundiced newborns is not known. The purpose of this study was to measure the rate of elimination of the principal bilirubin photoproduct, 4Z,15E-bilirubin, and to determine whether this is sufficient to Received June 22, 1984; accepted October 3, 1984. Address account for the decline in plasma bilirubin observed during phototherapy.Bilirubin, derived from the degradation of heme, is a potentially toxic, highly lipophylic molecule. In mammals this pigment is ravidlv cleared from the circulation and excreted as a ducuronide~onju~ate, primarily in the bile (2). Newborn i n f a k commonly develop hyperbilirubinemia due in part to a decreased ability to conjugate bilirubin and an increased pigment load. During vhototheravy, the most commonlv used treatment for unconj~~ated&~~dilirubinemia, bilirubin undergoes several reactions (3-7). All of these reactions yield photoproducts which are more polar and therefore presumably more easily excreted than native bilirubin. The fastest photochemical reaction is a Z to E isomerization reaction (5, 8) which in human infants yields primarily the 4Z,15E-bilirubin isomer (6). This reaction is readily reversible and up to 20% of the total bilirubin can be converted to this isomer during phototherapy (9-12).Since the quantum yield of the configurational isomerization reaction is at least 40 times greater than that for any other photochemical reaction of bilirubin (8), it has been assumed that the elimination of bilirubin during phototherapy is the result of formation and excretion of this photoproduct. We have used a rapid, quantitative HPLC method (5) to measure the half-life of the configurational isomer in serum of preterm infants undergoing phototherapy. We have found that the rate of elimination of the 4Z,15E-bilirubin isomer is much slower than previously reported (13) and cannot account for the decline in serum bilirubin observed in infants treated wit...

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Section: Discussionmentioning

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Phototherapy for Neonatal Jaundice: in Vivo Clearance of Bilirubin Photoproducts

et al. 1985

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“…Identification of the photoisomers was based on Chromatographie retention times. Extinction coefficients of photoisomers have been reported by several authors (2,29,30) but the values do not always agree. As we used different HPLC separation conditions, the detector response was not corrected for absorption differences of photoisomers at this wavelength, and the results are expressed as peak area.…”

Section: High Performance Liquid Chromatographymentioning

confidence: 90%

Influence of Photoisomers in Bilirubin Determinations on Kodak Ektachem and Hitachi Analysers in Neonatal Specimens. Study of the Contribution of Structural and Configurational Isomers

Gulian¹,

Dalmasso²,

Millet³

et al. 1995

CCLM

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We compared data obtained with the Kodak Ektachem and Hitachi 717 Analysers and HPLC from 83 neonates under phototherapy. Total bilirubin values determined with the Kodak and Hitachi are in good agreement, but we observed a large discrepancy in the results for conjugated (Kodak) and direct (Hitachi) bilirubin. HPLC revealed that all the samples contained configurational isomers, while only 7.7% and 30.8% contained conjugated bilirubin and structural isomers, respectively. We developed a device for the specific and quantitative production of configurational or structural isomers, by irradiation with blue or green light. In vitro, total bilirubin values are coherent for the routine analysers in the presence of configurational or structural isomers. With configurational isomers, unconjugated bilirubin (Kodak) is lower than total bilirubin (Kodak), and conjugated bilirubin (Kodak) is always equal to zero, so the apparatus gives a false positive response for delta bilirubin. In contrast, the direct bilirubin (Hitachi) is constant. Furthermore, in the presence of structural isomers, unconjugated bilirubin (Kodak) is unexpectedly higher than total bilirubin (Kodak), conjugated bilirubin (Kodak) is proportional to the quantity of these isomers, and direct bilirubin (Hitachi) is constant. The contribution of photoisomers in bilirubin measurements is discussed.

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“…Some of the (EE)‐C change (EZ)‐C for thermal and/or catalytic (E→Z) reversion in urine, like configurational photoisomers. The total amounts of these photoisomers in urine are very small compared to the amounts in serum, but these photoisomers in urine can be detected by using high‐performance liquid chromatography (HPLC) 1–4 .…”

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“…Configurational photoisomers include (ZZ)-BR, (EZ)-BR and (ZE)-BR, and structural photoisomers include (EZ)-C and (EE)-C. Some BR photoisomers, which had been very low in urine levels before phototherapy, have been detected in urine of neonates with hyperbilirubinemia during phototherapy. [1][2][3][4] Both serum (EZ)-BR and (ZE)-BR are excreted in urine, but serum (ZZ)-BR is not directly excreted in urine because of its hydrophobicity. 2 Detected (ZZ)-BR in the urine is reverted from urine (ZE)-/(EZ)-BR.…”

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Change of bilirubin photoisomers in the urine and serum before and after phototherapy compared with light source

Okada

Masuya

Kurono

et al. 2004

Pediatrics International

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Urinary Excretion of an Isomer of Bilirubin during Phototherapy

Cited by 26 publications

References 10 publications

Phototherapy for Neonatal Jaundice: in Vivo Clearance of Bilirubin Photoproducts

Phototherapy for Neonatal Jaundice: in Vivo Clearance of Bilirubin Photoproducts

Influence of Photoisomers in Bilirubin Determinations on Kodak Ektachem and Hitachi Analysers in Neonatal Specimens. Study of the Contribution of Structural and Configurational Isomers

Change of bilirubin photoisomers in the urine and serum before and after phototherapy compared with light source

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