Background: In the original glucose oxidase-peroxidase (GOD-POD) protocol, the time required to decrease the initial total bilirubin (TB) level by 20% is used for unbound bilirubin (UB) calculation. However, it needs to continuously monitor the TB levels by spectrometry.
Methods: Here, we hypothesized that the TB decrease during fixed time periods can also be used to extrapolate UB values (fixed-time protocol). Serum UB levels measured by the different protocols were compared using 10 newborn serum samples.
Results: Serum UB levels determined using the fixed-time protocol, especially using periods of 10 - 40 seconds, were strongly correlated with those determined using the original protocol (coefficient of determination > 0.9). The fixed-time protocol, using periods of 20 - 60 seconds, showed the high measurement precision (coefficient of variation < 5%).
Conclusions: The fixed-time protocol, using periods of 20 - 40 seconds, can help determine serum UB levels as effectively as the original protocol.