What is the principle of the transcutaneous bilirubin assay?

The transcutaneous bilirubin assay primarily utilizes multiwavelength reflectance photometry to measure bilirubin levels in the skin. This technique involves shining light at various wavelengths onto the skin and measuring the amount of light that is reflected back. The reasoning behind this method is that bilirubin, which is a yellow pigment, absorbs light differently at different wavelengths. By analyzing the reflected light, the device can estimate the concentration of bilirubin in the skin, which correlates with serum bilirubin levels.

Multiwavelength reflectance photometry is particularly useful in this context because it allows for the differentiation of bilirubin from other pigments and substances that might be present in the skin. This enhances the accuracy and reliability of the measurement while providing a non-invasive means to assess bilirubin levels, making it especially valuable in clinical settings for newborns and patients at risk of hyperbilirubinemia.