[Results] ALT 34 → 19 in seven months, nothing else changed
ALT 34 → 19 in seven months, nothing else changed. Numbers below. Ask me the boring questions, they are the useful ones. Brought the whole set to my clinician rather than one flagged value. Completely different conversation. How to make a panel worth comparing, which is most of the value people leave on the table.…
Why so many single values look alarming and turn out to be nothing.
A reference interval is built to contain about 95% of a healthy reference population, so one test in twenty falls outside one by construction. Add biological variation, assay imprecision, fasting state and time of day, and a genuinely stable person will produce occasional out-of-range results.
That is why repeat testing before acting is standard. Regression to the mean handles most of it. None of which means an out-of-range value should be ignored — it means it should be repeated and taken to somebody who can put it in context, which is emphatically not a ranked feed.
Tracked ferritin against the weight trend for a year. The correlation was much weaker than I expected and that was worth knowing.
assay method matters, especially between different labs
My fasting insulin moved and I spent a fortnight convinced I knew why. The repeat six weeks later was back in range and I had changed nothing.
baseline before you start is worth more than any later panel
Why so many single values look alarming and turn out to be nothing.
liver_enzyme_liz is right that a reference interval is not a target. It is a description of a population.