Total Bilirubin Measurement by Photometry on a Blood Gas Analyzer: Potential for Use in Neonatal Testing at the Point of Care

Neonatal jaundice is a common finding in neonates and has considerable impact on healthcare costs (1)(2)(3). Bilirubin at higher concentrations may cause kernicterus, a severe and often debilitating disease (4). Thus, jaundice may require phototherapy or even exchange transfusion to reduce plasma bilirubin concentrations (5). A decision-making process predominantly based on plasma bilirubin concentration is required in clinically jaundiced infants. Therefore, measurement of total bilirubin is one of the most frequently performed laboratory tests in newborns. For monitoring hyperbilirubinemia in the newborn, methods are desirable that provide fast but reliable results from very small volumes of whole blood, enabling bilirubin measurements at the point of care. We evaluated a new method that uses a blood gas analyzer with multiple-wavelength photometry to determine total bilirubin concentrations in whole blood from jaundiced and nonjaundiced neonates and compared the results with a standard clinical chemistry procedure for total bilirubin measurement in plasma. Samples were collected between April and June 2000 in a 40-bed nursery situated within the obstetrics department of the University Hospital. A total of 142 blood samples from 79 neonates (ages, 0–22 days) were investigated. Blood samples were obtained by heel prick and collected simultaneously into heparin-containing 55-μL capillaries (Radiometer Medical) and heparin-containing 200-μL microtubes (Sarstedt) used routinely for clinical chemistry determinations in our nursery. Oral informed consent was obtained from the parents.