Start with a baseline. A result taken before anything started converts most later ambiguity into a simple comparison, and it cannot be obtained retrospectively.
Same laboratory, same method, same time of day, same fasting state. Between-laboratory differences on several common analytes are larger than the changes people are trying to detect.
It helps to be literal here: a twenty-analyte panel run on a healthy person will produce, on average, one out-of-range result purely from how reference intervals are constructed. That is arithmetic rather than pathology.
Pre-analytical factors — posture, tourniquet time, fasting, sample handling — are the largest source of error in routine biochemistry, well ahead of the analysis itself.
Same laboratory, same time, same fasting state, or the comparison is not a comparison.
2Is the assay method stated on your report? Two immunoassays for the same analyte do not agree with each other. – zeynep_arslan 5 months ago add a comment