Alpha feto protein is one of several analytes expressed as a result of “growth” within the human body. This can be good or bad “growth”. For pregnant mothers, AFP is one of the analytes followed in maternal screens in the second trimester. In that instance, it’s viewed in an “encouraging” light, ascertaining healthy pregnancies (good growth).
However, AFP is also an analyte expressed by tumors (bad growth). In this instance, AFP’s may be drawn on patients undergoing oncology treatments. The tracking of keeping a low AFP value is pertinent to ensuring appropriate therapy and prognostics for the patient.
The committee asked for separate LOINC codes for the AFP.tumor markers, because this analyte will be trended over time for the course of fighting the cancer. The values should be kept separate in repositories (AFP vs AFP.TM), because reference ranges and collation of data vary.
Thank you so much for detailed explanation. But there is still another question: should LOINC create a separate concept for pregnant APF? This is because, I think, the AFP is just a general concept and it couldn’t explicitly represent something like AFP.Pregnant. Would the LOINC committee create such a unique concept for pregnant APF?
The LOINC committee held an early discussion on pregnancy being a temporary challenge to the patient, and possibly afflicting lab values. As I recall, we concluded that the chart should be considered as the full document on what was happening to the patient, and having a condition/diagnosis such as pregnancy or diabetes noted in the chart would suffice. Having a physiologic stress or challenge of caloric fasting, exercise or fluid fasting do have modifiers added to LOINC codes, otherwise the challenges delineate dose and timing of a chemical challenge. See the LOINC User’s Guide for additional information.