The Luminex multiplex assay for the definition of HLA antibodies was introduced 20 years ago. To date, although the assay is simple and straightforward, the interpretation of the results remains a conundrum. Making use of the so-called mean fluorescence value only does not help since this value is relative, the day-to-day variation is significantly large, and the user variation is beyond acceptable ranges. Within the same range of problems, the cutoff value used to classify HLA-specific antibodies as being either present or absent varies between laboratories. This threshold influences clinical decision-making. In addition, the readout value is used to diagnose the amount of HLA-specific antibodies after treatments like absorption, plasmapheresis, or transplantation, overlooking the relative nature of the value. In this study, we show bead variability for HLA class I and HLA class II based on negatively defined bead reactions with a mean fluorescence value below 1500 and self-antigens. In an effort to circumvent the assay’s inherent problems, we introduced the term ratio. For each serum sample, a paired sample from before the treatment is run in parallel. The ratio of post-treatment to pre-treatment can then be used to characterize antibody dynamics: a ratio above 1 reflects increased antibody production and a ratio below 1 indicates a decrease in antibodies in the serum. This value may offer the possibility to make more informed and adaptive treatment decisions.