A single out-of-range value on an otherwise normal panel posts 31–60
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
An observation about single out-of-range value that I cannot explain and am posting anyway, on the principle that unexplained observations are more useful public than private.
Post #32 answers the question as asked. The question underneath it is different.
Keeping your own results in a single table with dates is more useful than any individual result in it, and almost nobody starts early enough.
Nothing above should be read as advice about what anyone else should do.
A single value outside interval: usually uninformative on a single draw. What makes a result interesting: a trend across multiple draws, a magnitude well beyond the interval, a pattern that coheres with other values, or symptoms that fit.
Glycaemic markers integrate over different periods. A point glucose and a longer-term marker disagreeing is not a contradiction; it is two different questions.
The step people skip is the one I have spelled out.
Where I part company with post #35, and it is a narrow parting.
Single out-of-range value was covered in the wiki last year and the page has a review date on it, which is a better starting point than my memory of a thread.
Bookmarking this. I will come back when I have something worth adding.
I would put moderate confidence on the mainstream reading of single out-of-range value and no more. That is not scepticism for its own sake; it is where the sourcing actually stops.
General information rather than advice about anyone's care. A single value outside a reference interval, on a single draw, in an otherwise unremarkable panel, is usually uninformative.
Post #41 is the version of this I will quote in future. One addition.
Lipid panel interpretation: total, LDL, HDL, triglycerides all on one panel. Reading them together is more informative than reading one value in isolation. An elevated triglyceride with low HDL is different from triglyceride elevation alone.
I looked this up rather than remembered it, which is the right order.
Where I part company with post #42, and it is a narrow parting.
Time of day: some biomarkers vary across the day. Cortisol in the morning differs from cortisol in the evening. Comparing results from different times of day is comparing things that are not the same.
That is what I would do. It may not be what is correct.
The arithmetic in post #44 is right; the assumption feeding it is the part to check.
Keeping your own results in a single table with dates is more useful than any individual result in it, and almost nobody starts early enough.
On reflection I would soften that slightly.
Nothing in this subcategory is medical advice, and a panel with an unexpected result is precisely the situation where that matters.
The evidence for this is thinner than the way I have phrased it suggests.
Collapsed as off-topic by two members at trust level 3 or above
Adding the boring version of single out-of-range value, because the interesting version keeps getting posted and the boring one is usually right.
Check the ordinary explanations, in order, and stop when one of them accounts for what you are seeing. Most of the time the second one does.
Post #46 put the caveat in the right place and I want to underline it.
The confident answers on single out-of-range value and the well-sourced answers are not the same answers, which is the most useful thing I have learned reading this category.
Quietly grateful for the plain phrasing. Not every thread gets that.
Answering the single out-of-range value question as asked, then the question I think is meant. As asked: yes, with the qualification below. As meant: it depends on how the first measurement was taken.
Collapsed as off-topic by two members at trust level 3 or above
On single out-of-range value: the maintained page in the documentation commons covers the general case with citations and a review date, which is more reliable than any reply here including this one.
Post #49 describes the usual case. This is about the unusual one.
Time of day: some biomarkers vary across the day. Cortisol in the morning differs from cortisol in the evening. Comparing results from different times of day is comparing things that are not the same.
None of the above is medical advice and I am not qualified to give any.
Nobody has said the unglamorous part of single out-of-range value yet, so: most of the variation is explained by things that are boring to write about and easy to check.
Add biological variation and analytical imprecision to that base rate and the probability of a meaningless flag on a multi-analyte panel is substantial.
On post #53 — agreed on the reasoning, with one qualification.
The reason single out-of-range value keeps being re-asked is that the answer is conditional and people quote it without the condition. It is not that the answer is unknown.
Picking up post #57: that is the part I would want checked first.
A trend needs at least three points to be a trend. Two points are a line and a line through noise is still a line.
Not a strong opinion, just a consistent one.
Coming back to post #57, because the follow-up matters more than the original answer.
Repeat before acting is standard practice for an isolated abnormal result on most analytes, and it is standard for a reason.
Happy to be corrected if someone holds better data than mine.
Where a panel includes a calculated value, that value inherits the imprecision of everything it was calculated from and is usually reported without an interval.
A guess, clearly labelled as one.