Transcutaneous bilirubinometry in normal Japanese infants.

We performed TcB readings in healthy full-term breast-fed Japanese infants from birth to seven days, and attempted to establish the normal range. TcB readings from Japanese infants were significantly higher over a longer period compared with Caucasian infants. The age of peak TcB readings in Japanese newborn infants was day 6, significantly later than that of Caucasian infants, day 3-4. We also attempted to estimate the total serum bilirubin concentrations using regression line relating TcB readings to serum bilirubin concentrations. Our study demonstrated that estimated total serum bilirubin concentration from forehead TcB readings was 0.56 +/- 0.35 mg/dl at birth, thereafter increasing to 6.8 +/- 0.5 mg/dl on day 1 and reaching a maximum of 12.6 +/- 2.5 mg/dl on day 6. These values and pattern in Japanese neonatal jaundice were significantly different from those of Caucasian children, but were similar to values and patterns from American Indians, Alaskan Eskimo, and other Asian full-term newborn infants. Thus TcB measurement may be useful for observation of the course of neonatal jaundice.