Ha Ha that roscoe88 is a challenge. Many have tried to help him. He is one unique fellow.
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HI johann77 what are you trying to say? Lets face it Lab fuck up all the time. Why do you need back ground info?
I am saying that the biologic variability is most of the times simply higher than the analytical variability. Thats just how a biologic system works.
I do bioanalytical chemistry as a profession. Now involved for quite some time in pharma R&D but worked in a medical lab for some years before. Just trying to provide some background.
Clinical laboratory is quite a strictly regulated field. I experienced a couple of inspections by our local health authority. You better be able to explain what you did and what you were doing or you get into troubles.
Some regulations specific for the US can be found here.
@johann77 - quick questionā¦ Why do different labs have different reference ranges, how are those reference ranges calculated and how/why do they change over time?
Any info is appreciate.
Thanks, but Iām not following your point.
Sorry. What i ment was that I would like to provide some background info on this topic with my post and i hope that it is a meaningful contribution.
Different labs use the same assay principle (eg immuno type assay) but the assay protocol might be sligthly different (e.g. different vendor, different chemicals to make the assay compatible with automatization etc).
The ref ranges are then established by either of two ways.
- the labs takes over the generally accepted reference ranges. It buys standards (eg a sample with an exact amount of the analyte) and calibrates their test to the reference sample.
Lets assume the accepted lower ref range is 350 measured with a particular assay.
You can buy a reference sample containing exactly 350 ng/dl and measure it using your adapted procedure. When your assay results in a value of 315, then this would be the lower ref range for this lab using the adapted method.
- another option is that the lab itself establishes the āhealthly rangeā on its own. This is typically not done, but very large labs might decide to do so. They sit on an anormous amount of data and calculate their own reference range using statistics.
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What is your take on immunoassay vs. liquid chromatography dual mass spectrometry for estradiol assessment? I have looked into this and been able to speak directly with a couple of people that do what you do. Iāve also been building a database of results with both test run on the same sample.
I actually just did lab I just ran the regular e2. Sensitive takes 3 days. And from all the labs I did the results of both assays were always within a few points of each other
Which was higher?
Hereās a few of mine.
Sensitive 22.5
Regular estradiol 27.5
S 29.2
23.0
S 32
27.6
Same lab. Different dates. So sometimes itās higher. Sometimes not.
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Me too, plus Iāve been getting them from a few other guys. Here is my latest:
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Here is another, is not mine:
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The MS method is superior to the immunoassay method in terms of specificity, reproducibility and sensitivity in the male E2 range.
Especially the reproducibility and accuracy of the immunoassay method at levels below 20 pg/ml is very bad. In this range the immunoassay tends to overestimate E2 due to a lack in specificity. At above 20 pg/ml accuracy gets better but still reproducibility is bad (eg a bit simplified: true value 20, measured immunoassay between about 15 and 60; true 20 measured MS between 17 and 30).
The E2 assay is a really bad assay, if you have the choice definitely go for the MS assay.
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Iāve seen that paper. Interesting, Iām not seeing that, more often than not, LC comes back higher than IA. Not just with me either.
Forget the studies, what is your personal experience working with both methods?
We only had IA based methods implemented so canāt provide my personal experience when it comes to the comparison between IA and MS.
In our lab reproducibility of the E2 test was also quite bad. We participated once in a ring study with a defined sample (spiked E2 at 28). Results of 8 replicates performed by 2 different operators varied between low 20s and high 40s.
A total of 9 labs participated all using IA, lowest result was around 14 (if I remember correctly, itās 14 years ago) and highest in the 60s.
Yes, IA based E2 assay sucks.
My department now in pharma does MS and we can measure parts per million levels of impurities with a reproducibility of Ā±30%.
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Thanks.
Thatās a large discrepancy, itās the difference between spot on E2 and E2 in need of reduction for some men.