Optimization of an Algorithm for Hemoglobin Interference Compensation on a Simple Photometer for Bilirubin Measurement

Excessive amounts of bilirubin in neonates, a condition known as neonatal hyperbilirubinemia, can cause neurological impairments and, in extreme cases, bring to death especially in constrained settings as Low- to Middle Income Countries (LMICs). This pathological condition occurs in one in ten newborns and can be prevented with timely and reliable monitoring of bilirubin concentration. Various technologies have been developed for both laboratory and point-of-care scenarios, with direct spectrophotometry-based devices being among the most widely diffused. While these devices can meet LMICs' specific requirements, simpler and portable applications often face interference, particularly from substances like hemoglobin. In this study, a simple two-wavelengths reflectance photometer was used to assess the performance of four different wavelengths (570, 575, 590, and 605 nm) for the compensation of hemoglobin interference on bilirubin measurement: the insensitivity to bilirubin of each wavelength was verified by testing non-hemolyzed plasma samples with six different bilirubin concentrations (0.5-30 mg/dL), while the sensitivity to hemoglobin was verified by testing plasma samples having five different hemoglobin concentrations (0.41-1.21 g/dL). Kruskal-Wallis tests were conducted for both panels, demonstrating sufficient independence from bilirubin concentration and dependence on hemoglobin concentration across all tested wavelengths. Overall, the 590 nm wavelength was considered the most promising, exhibiting a substantially independent behaviour from bilirubin (R
²
=0.016, p=0.23) and a strong dependence on hemoglobin (R
²
=0.996, p<0.001).