title: Serum unbound bilirubin as a predictor for clinical kernicterus in extremely low birth weight infants at a late age in the neonatal intensive care unit.
abstract: BACKGROUND
  This study aimed to evaluate peak serum total bilirubin (TB) and unbound bilirubin (UB) levels in preterm infants with clinical kernicterus (KI) who were diagnosed by clinical findings during infancy.
  
  
  METHODS
  For this multicenter retrospective study, 18 Japanese extremely low birth weight (ELBW) infants with clinical KI were included. Clinical KI was diagnosed based on the presence of motor developmental impairment with/without athetosis, and abnormal magnetic resonance imaging or brainstem auditory evoked potential findings during infancy. High and low TB or UB levels were defined as serum TB levels ⩾ and <15 mg/dL or serum UB levels ⩾ and <0.8 μg/dL, respectively. The clinical characteristics of KI preterm infants were analyzed. The proportion of infants with high or low serum TB levels and with high or low serum UB levels was then investigated. Sensitivity and specificity were calculated.
  
  
  RESULTS
  In 18 KI infants, the median age when serum TB levels peaked was 28 days after birth. In eight KI infants with low serum TB levels, 88% of them had high serum UB levels. For comparison of the number of infants who had high or low serum TB and UB levels, the sensitivity was 90% and specificity was 13%.
  
  
  CONCLUSIONS
  Serum TB and UB levels peak at a later age than expected. Chronic serum UB monitoring may be helpful for identifying ELBW infants at risk for developing KI, even when they do not have high serum TB levels.
authors: Department of Pediatrics, Kobe University Hospital, Kobe, Japan. Electronic address: ichim@med.kobe-u.ac.jp.
authors: Ichiro
authors: I
authors: Morioka
authors: Department of Pediatrics, Kobe University Hospital, Kobe, Japan.
authors: Hajime
authors: H
authors: Nakamura
authors: Department of Pediatrics, Kobe University Hospital, Kobe, Japan.
authors: Tsubasa
authors: T
authors: Koda
authors: Department of Neonatology, Kobe Children's Hospital, Kobe, Japan.
authors: Hitomi
authors: H
authors: Sakai
authors: Department of Pediatrics, Kobe University Hospital, Kobe, Japan.
authors: Daisuke
authors: D
authors: Kurokawa
authors: Department of Pediatrics, Kakogawa West Municipal Hospital, Kakogawa, Japan.
authors: Masahiko
authors: M
authors: Yonetani
authors: Department of Pediatrics, Kakogawa West Municipal Hospital, Kakogawa, Japan.
authors: Takeshi
authors: T
authors: Morisawa
authors: Department of Pediatrics, Takatsuki General Hospital, Takatsuki, Japan.
authors: Yoshinori
authors: Y
authors: Katayama
authors: Department of Pediatrics, Yodogawa Christian Hospital, Osaka, Japan.
authors: Hiroshi
authors: H
authors: Wada
authors: Department of Pediatrics, Yodogawa Christian Hospital, Osaka, Japan.
authors: Masahisa
authors: M
authors: Funato
authors: Department of Pediatrics, Chibune General Hospital, Osaka, Japan.
authors: Akihiro
authors: A
authors: Takatera
authors: Department of Pediatrics, Juntendo University Hospital, Tokyo, Japan.
authors: Akihisa
authors: A
authors: Okumura
authors: Clinical Laboratory, Kobe University Hospital, Kobe, Japan.
authors: Itsuko
authors: I
authors: Sato
authors: Clinical Laboratory, Kobe University Hospital, Kobe, Japan.
authors: Seiji
authors: S
authors: Kawano
authors: Department of Pediatrics, Kobe University Hospital, Kobe, Japan.
authors: Kazumoto
authors: K
authors: Iijima
mesh_terms: D001663:Bilirubin / Q000097:blood*; D005260:Female; D006801:Humans; D007223:Infant; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D007363:Intensive Care Units, Neonatal; D007647:Kernicterus / Q000097:blood* / Q000175:diagnosis; D008297:Male; D012189:Retrospective Studies
chemical_list: D001663:Bilirubin
keywords: Athetosis; Brainstem auditory evoked potentials; Jaundice; Magnetic resonance imaging; Motor impairment