This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.
Post #58 and I disagree about the size of the effect, not about the direction.
Fasting versus non-fasting has been discussed here with more heat than it deserves, mostly because two definitions have been in play the whole time.
Adding a note of thanks rather than an opinion. I did not know most of that.
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.
Posted with less confidence than the sentence structure implies.
Analytical imprecision: any measurement has an error margin. A small difference in consecutive tests is usually measurement noise, not a real change. Knowing the imprecision helps distinguish noise from signal.
A partial answer, offered because a partial answer beats none.
Post #61 put the caveat in the right place and I want to underline it.
Fasting state: some lab tests require fasting; others do not. Lipids on a fasting draw differ from lipids on a fed draw. Always note whether the test was fasting when comparing results.
Adding this to the thread rather than to the wiki, because I am not confident enough for the wiki.
Fasting versus non-fasting would be much easier to settle if anyone reported the denominator. Almost nobody reports the denominator.
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.
Answering the fasting versus non-fasting 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.
Nobody has said the unglamorous part of fasting versus non-fasting yet, so: most of the variation is explained by things that are boring to write about and easy to check.
This follows post #72 rather than contradicting it.
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.
Take the reasoning and check the arithmetic; I do not always get it right.
This is the answer, and the reason it is the answer is the more useful part.
Reading back through the fasting versus non-fasting threads from last year, the same three questions come up every time and only one of them has ever been answered properly. That seems like a documentation gap rather than a knowledge gap.
Repeat before acting is standard practice for an isolated abnormal result on most analytes, and it is standard for a reason.
Where I have landed on fasting versus non-fasting, having got it wrong once in public: the direction is clear, the magnitude is not, and anyone quoting a precise magnitude has borrowed it from somewhere that did not measure it.
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