I wonder how LOINC can be used to store potassium determinations from serum and plasma separately and uniquely identifiable. Apparently there is only one LOINC code for serum and plasma together. Both source materials are very different and therefore have different reference values.
Please see page 40 of the LOINC User’s Guide for a detailed explanation of the early LOINC development guidelines involving serum or plasma systems. We hope you will provide a few examples of analytes referred in your email, so the conversation can continue.