Can sunlight replace phototherapy units in the treatment of neonatal jaundice? An in vitro study

Light can be efficiently used for the treatment of neonatal jaundice. Sunlight, which covers a large portion of the light spectrum including the bilirubin-absorbing range, is abundant in the Middle East. Such advantages prompted the present study to investigate the efficiency of sunlight in isomerizing bilirubin. This may introduce a practical source of light for the treatment of hyperbilirubinic infants in areas where phototherapy units are not available.

The efficiency of sunlight was quantified by a comparison with a phototherapy unit. Aqueous bilirubin solutions were exposed to periodic sunlight over the entire year and the reduction of bilirubin concentration was monitored spectrophotometrically. Bilirubin solutions were also exposed to a phototherapy unit intensity comparable to that of sunlight (17 cm away from the source).

The data indicated that at this comparable light intensity, the phototherapy unit was as effective as sunlight. However, for the treatment of neonatal jaundice, phototherapy units are usually operated at a distance of 50 cm (where the light intensity is six times less than that of sunlight). When this distance was tested, only 16% of bilirubin was isomerized in the first 5 min of exposure. In contrast, about 65% of bilirubin was isomerized when the phototherapy unit was placed at a distance of 17 cm and when the bilirubin solutions were exposed to sunlight for the same time period. The hourly and seasonal changes in sunlight intensity affected the reduction in bilirubin concentration significantly.

Data revealed that sunlight is almost 6.5 times more effective than a phototherapy unit when operating at the ward geometry after taking isomerization efficiency and area of exposure into consideration. Moreover, sunlight is still more effective during the winter season, when its intensity is lower. Thus, sunlight may be considered an alternative phototherapy source for the treatment of neonatal jaundice, particularly in areas where conventional phototherapy units are unavailable.