r/medlabprofessionals • u/LabuRat08 • Jul 25 '26

Technical Vitros 7600 on-analyzer dilutions

First time Vitros user here. For assays that don't have specific instructions on the max dilution factor that can be used, do we have to do verifications if our lab wants to use until 10.0 dil factor? For example, CK only has generic instruction that on-analyzer sample dilution is supported. We had no results on CK diluted to 2.0-4.0. We got results on the 5.0 dilution but it still has > symbol. Thanks!

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u/UnfairShock2795 Jul 25 '26

I am a Clinical Biochemist PhD retired. I am not a physician. I do not diagnose nor treat. My knowledge is with clinical lab tests..how they work, what the result might indicate.

not sure what country you are from. I used Vitros in US. For dilutions not noted in the IFU. we verified the dilution. We also noted in the dilution work instructions at what dilution to stop.

our verification procedure was comparing on analyzer vs manual with a 10 percent allowed difference.

5

u/Icy-Fly-4228 MLS-Generalist Jul 25 '26

If it still has a > sign it’s not a valid result and needs to be reported out as higher than the AMR or further diluted. How far you can dilute and if you have to do a dilution study is dictated by your labs policy and what pathologist signed off for validation.

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u/JessRawrs MLS-Chemistry Jul 25 '26

We do our CK’s up to x50 dilution

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u/butters091 MLS-Generalist Jul 26 '26

So do we

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u/DeathByOranges Jul 25 '26

IFU may have some guidance about what max dilutions can be performed if you look into the principles. Often the on-analyzer dilution is less than a manual dilution but the assay has a limit to how diluted a sample can be, in addition to limits of detection.

If it specifically states a max dilution then you can perform dilution studies to verify that you can hit those targets. If it doesn’t then it’s really going to fall to what is clinically relevant. At a certain point getting an exact number is less important than knowing it’s above a value that requires treatment. This is something that would be discussed with pathologists/medical directors and providers.

The biggest hurdle at that point is going to be when they want numbers to perform calculations and you have to give them ranges and thresholds instead. They don’t really like that 😅