Proc. Nati Acad. Sci. USA Vol. 78, No. 3, pp. 1882-1886, March 1981 Medical Sciences

Photoisomerized bilirubin in blood from infants receiving phototherapy (fluorescence/photobiology/neonatal hyperbilirubinemia)

ANGELO A. LAMOLA*, WILLIAM E. BLUMBERG*, RICK MCCLEADtt, AND AVROY FANAROFFt *Bell Laboratories, Murray Hill, New Jersey 07974; and tDepartment of Pediatrics, Case-Western Reserve Medical School,

Clev'eland, Ohio 44106

Communicated by William 0. Baker, November 17, 1980

ABSTRACT A pigment different from (Z,Z)bilirubin-IXa was from newdetected by fluorometric methods in blood for unconjugated hyborn infants undergoing blue-light therapy specimens perbilirubinemia; it was not detected in specimens from infants not under therapy. The phototherapy-associated pigment has fluorescence, solubility, and photochemical properties that are identical to those exhibited by what are thought to be configurational (Z -* E) isomers of bilirubin. It is concluded that isomerized bilirubin in the blood of neonates under phototherapy can reach as high as 15% of the total.

METHODS Specimens. Specimens from infants were obtained by heel stick or via an umbilical catheter. Required authorization was obtained before collection of each specimen. Heparin was the anticoagulant in all specimens. Phototherapy lamps were off during blood collection. Direct diazo-reacting bilirubin was