1 Department of Pediatrics, University of Colorado Medical Center, 4200 East Ninth Avenue Denver 20, Colorado
Recent studies of bilirubin and its two glucuronides in the serum of newborn infants suggested that the monoglucuronide was an important intermediate in the conjugation process and that its ratios to bilirubin itself and to the diglucuronide might be a helpful index of the need for exchange transfusion.
The studies reported here suggest that these conclusions may be unfounded and that there are certain important intrinsic errors in conventional extraction procedures.
The principle of the extraction method described by Eberlein is that when bilirubin in serum is diluted in a pH 5 phosphate buffer and extracted with ethyl acetate, unconjugated bilirubin is quantitatively extracted into the organic solvent.