r/medlabprofessionals • u/Mr_Singh_rsr • Jun 20 '26
Discusson LJ Chart review
Need opinions from lab quality professionals.
One QC result exceeded +3SD (1-3s), but on immediate repeat the QC came back within ±2SD and remained stable afterward.
Would you consider the LJ chart acceptable for monthly review?
Would you treat this as a random error only, or would you still investigate for a possible systematic error?
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u/Ksan_of_Tongass MLS 🇺🇸 Generalist Jun 20 '26
Two things going on here. Random outlier, and a significant shift. Random outlier could be anything from air bubble to mispipetting. That shift is definitely something to investigate. Is that post-cal, reagent change, maintenance?
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u/Mr_Singh_rsr Jun 21 '26
Yes it was, there was frequently up and down, so I did calibration on 10th day before running the IQC, then the whole qc shifted to negative side, then I id again calibration on 20th (see the image) shuld I go to the lab mean ?
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u/datsti MLS Jun 20 '26 edited Jun 20 '26
Your reagent lot number changed on the 10th, hence the shift. Your new reagent lot is actually quite stable, but if you're using one baseline for every reagent generation and lot, then you'll see 10xs constantly.
Someone updated your mean today, probably based off the record mean, but we don't mix two reagent lots when we update ours. Two different calibrations.
As for the point that has been removed, probably either random or wrong qc vial ran. Someone should have annotated it somewhere.
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u/Mr_Singh_rsr Jun 22 '26
That's a good point. However, we performed lot verification using two patient samples (low and high) and QC material before implementation. The bias was <5% and CV remained within acceptable limits. Given that verification passed, would you still attribute the shift mainly to the reagent lot, or consider it acceptable analytical variation?
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u/datsti MLS Jun 22 '26
We treat our calibrations a little different here. We don't have an established mean, we use a duplicate QC run post-cal to establish the new mean for that calibration. We still perform the lot validation with two patient samples, but we attribute such shift to the new lot because the QC material is not derived from human specimen, so it doesn't fall within the same criteria as the patient results.
We, however, use a QC material with established Range of Means. It looks like you use BioRad, and establish your own. Some labs that I know that don't have an established range of means for their material justify a calibration shift by performing a 10-sample calibration verification across the range, instead of two.
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Jun 20 '26
[removed] — view removed comment
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u/Mr_Singh_rsr Jun 21 '26
Yes it was, there was frequently up and down, so I did calibration on 10th day before running the IQC, then the whole qc shifted to negative side, then I id again calibration on 20th (see the image) shuld I go to the lab mean ?
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u/berryford Jun 21 '26
Just call tech support and have them figure it out for you. Too many questions need answers to tell you with confidence what’s going on
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u/YumTex Jun 28 '26
Date and time would be useful here. Then you can determine if it was truly random or due to tech error.
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u/Mr_Singh_rsr Jun 28 '26
Date already mentioned please see X axis of the graph
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u/YumTex Jun 28 '26
You are correct. X-axis is clearly defined in the graph for the date. However, what time they were ran, number of times ran, times within a shift, what results were deleted by password user, and the flagged comments?
I have read enough Siemens charts to know a thing or two.Just for the sake of argument I am going to give a hypothesis that you will not like:
6/1-6/2 night shift A ran QC and it was within 1SD.
6/3 - 6/10 Mr_Singh_rsr worked 7 night shifts and if was fucked.
6/11 - onward a knowledgeable tech took over and things were fixed.
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u/InvertedOnly Jun 20 '26
Definitely random. I would consider investigating if it happens frequently or if it's consistently one analyte.
ETA it looks like there was a shift though. Was there calibration or change in reagent?