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Hello,
A question has arisen in our team regarding the reporting of values
below LLOQ of a bio-analytical method. Some of us have been arguing
that a give LLOQ, say 1 ng/mL, means that any value determined below
1 ng/mL should be reported asthat one can report values below 1 ng/mL as long as they are within
the precision of the method or even above the LLOQ-0.20*LLOQ or above
0.8 ng/mL in this case. Has there been any discussion on this
subject on this list?
Thanks so much
Luis Sojo
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The following message was posted to: PharmPK
There has been a lot of discussion, and there may be some change coming.
But until we accept a different guidance the prudent thing is to report
values that are less than the LLOQ as <LLOQ.
Ed O'Connor, PhD
Technical Director, Immunoanalytical
Tandem Laboratories
115 Silvia Street
West Trenton, New Jersey
609-228-0243
ed.oconnor.-at-.tandemlabs.com
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Dear Luis,
While reporting concentrations for PK run, we need to report all
concentrations below the theoretical LLOQ concentrations as BLQ. Now,
in your case, any value which is less than 1.0 ng/mL should be
reported as BLQ. Just to elaborate this point, for example, suppose
the ULOQ concentration is 100.0 ng/mL and if for the unknown sample
at any given time point the back-calculated concentration goes beyond
100.0 but less than 115.0 ng/mL which is within the limit of +15% of
ULOQ, even then we need to repeat the sample under code such as
"sample concentration beyond ULOQ". The reason why you should not
consider 0.8 ng/mL as accepted value for data evaluation purpose is
that as per the guidelines, we are not supposed to do extrapolation
of Standard Curves below LLOQ of above ULOQ which means we need to
consider only those concentrations of unknown samples which fall
within the theoretical range of Calibration Curve Standards.
I hope it helps.
Regards
Neel K Mohan
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