Noninvasive transcutaneous bilirubin measurement in adults using skin diffuse reflectance

Abstract

Accurate measurement of bilirubin concentration in adults is crucial for the diagnosis and management of liver and biliary tract diseases. Traditional methods relying on central laboratory testing pose challenges such as invasiveness, patient discomfort, and time consumption. Non-invasive alternatives have been explored, but their applicability to adult populations remains uncertain. This study aimed to develop and validate a portable non-invasive optical system based on spatially resolved diffuse reflectance spectroscopy (DRS) specifically tailored for adult transcutaneous bilirubin measurement. Forty-two adult patients with various underlying conditions were included in the study. Comparisons between transcutaneous bilirubin values measured by the DRS system and total serum bilirubin concentrations obtained through blood tests revealed strong correlations, particularly at the neck (r = 0.872) and the medial side of the right upper arm (r = 0.940). Bland-Altman analyses demonstrated substantial agreement between the transcutaneous bilirubin values and total serum bilirubin concentrations. The results highlight the potential of the non-invasive DRS system as a convenient and reliable tool for monitoring bilirubin values in adults.

Fig. 1.

Schematic setup of the spatially resolved diffuse reflectance spectroscopy system employed in this study. The system consisted of a white LED, a spectrometer, a fiber switch, a fiber probe, and a laptop computer. Lower left shows the detail configuration of the fiber probe.

Fig. 2.

Correlation plots comparing transcutaneous bilirubin values (measured using DRS) with total serum bilirubin concentrations (obtained from blood tests) at five measurement sites: (a) forehead, (b) cheek, (c) neck, (d) medial side of the left upper arm, and (e) medial side of the right upper arm.

Fig. 3.

Bland-Altman plots showing the bias and 95% limits of agreement between transcutaneous bilirubin values and total serum bilirubin concentrations at the five measurement sites: (a) forehead, (b) cheek, (c) neck, (d) medial side of the left upper arm, and (e) medial side of right upper arm.

Fig. 4.

The analysis of fitting quality for subject No. 029, depicting the recovered skin absorption spectrum (black line) and the best chromophore fitting spectrum (red dotted line) at various measurement sites: neck (a), forehead (b), right upper arm (c), and left upper arm (d).