Infrared irradiance from phototherapy units and the effect on osmolality of serum and urine in term infants.

The osmolality of urine increased in 10 term infants receiving phototherapy. Phototherapy units made locally were likely to emit more infrared radiation than a unit available commercially, but both types led to falsely increased incubator thermometer readings. Interposing a 6-mm acrylic sheet prevents these effects.