title: Is bilirubin/albumin ratio correlated with unbound bilirubin concentration?
abstract: BACKGROUND
  The American Academy of Pediatrics guidelines recommend that the total bilirubin (TB)/albumin (Alb) ratio (B/A ratio), instead of serum concentration of unbound bilirubin (UB), can be used with TB for determining treatment modality for jaundiced newborns ≥ 35 weeks of gestation. It is unknown, however, whether the B/A ratio is actually correlated with serum UB.
  
  
  METHODS
  Four hundred and ninety-seven serum samples were obtained from 209 newborns ≥ 35 weeks of gestation, who were admitted to Kobe University Hospital. Serum UB concentration was measured using the glucose oxidase-peroxidase method. Serum TB and Alb concentrations were measured on spectrophotometry. B/A ratios were calculated and were linearly compared with serum UB. Furthermore, the accuracy of the B/A ratio was evaluated.
  
  
  RESULTS
  The B/A ratio was significantly correlated with serum UB concentration. A serum UB concentration of 0.6 µg/dL was in agreement with a B/A ratio of 0.5. For comparison of the number of newborns who had serum UB concentrations ≥ or <0.6 µg/dL and B/A ratios ≥ or <0.5, we found the following characteristics: the concordance rate between serum UB concentrations and the B/A ratio was 94%, sensitivity was 51%, and specificity was 99%.
  
  
  CONCLUSIONS
  The B/A ratio is significantly correlated with serum UB concentration in newborns ≥ 35 weeks of gestation. The B/A ratio, however, is underestimated when serum UB concentrations are >0.6 µg/dL.
authors: Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan.
authors: Yumi
authors: Y
authors: Sato
authors: Ichiro
authors: I
authors: Morioka
authors: Akihiro
authors: A
authors: Miwa
authors: Tomoyuki
authors: T
authors: Yokota
authors: Kiyomi
authors: K
authors: Matsuo
authors: Tsubasa
authors: T
authors: Koda
authors: Kazumichi
authors: K
authors: Fujioka
authors: Satoru
authors: S
authors: Morikawa
authors: Akio
authors: A
authors: Shibata
authors: Naoki
authors: N
authors: Yokoyama
authors: Kaoru
authors: K
authors: Takahashi
authors: Hisahide
authors: H
authors: Nishio
authors: Masafumi
authors: M
authors: Matsuo
mesh_terms: D000418:Albumins / Q000032:analysis* / Q000378:metabolism; D001663:Bilirubin / Q000097:blood* / Q000378:metabolism; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007567:Jaundice, Neonatal / Q000097:blood*; D008297:Male; D011485:Protein Binding / Q000502:physiology; D012709:Serum Albumin; D000075462:Serum Albumin, Human; D013053:Spectrophotometry
chemical_list: D000418:Albumins; D012709:Serum Albumin; C053498:albumin-bilirubin complex; D001663:Bilirubin; D000075462:Serum Albumin, Human