Hi, I’ve noticed this too following a recent comparison across manufacturers.   Roche seem to be stand-alone by using this nomenclature, which they have determined using a different procedure (n=21, within run imprecision) to that which they use to define LOD (n=60 of the blank + 2SDs of low conc. sample, CLSI approach essentially). I don’t find this additional parameter useful, least to say I wouldn’t be happy reporting to a concn. <LOD (or <LLOQ)! 

 

…Changing tac briefly from PSA to high sensitivity cTn and use of the LOD for ACS r/o. This perhaps represents somewhat of a paradigm shift as regards testing and reporting in general terms however is it more acceptable/palatable to report to the LOD for hs-cTn because it’s in the guidelines and perhaps a larger body of (robust) evidence supporting its use compared to that available re. use of PSA’s LOD for monitoring biochem. recurrence?...same/similar issues of quality control/assurance though to contend  with in both circumstances? (Australian report noted earlier from mailbase..chilling!). 

 

KR, Graham

 

Dr Graham Lee PhD FRCPath

Consultant Clinical Biochemist/UCD Assistant Clinical Professor

Department of Clinical Biochemistry & Diagnostic Endocrinology

Mater Misericordiae University Hospital and

Cappagh National Orthopaedic Hospital, Dublin

Midland Regional Hospital, Mullingar, University College Dublin

Address: MMUH, Eccles St, Dublin 7

Tel:00353 1 8034983

 

 

 

Dear Colleagues,

 

 

Is it possible for lower detection limit to be less than LoB?

 

According to EP17A; “lower limit of detection” also stands for LoD. It will also be the case that, LoB<LoD£LoQ.

 

I think, first this discrepancies on Roche PSA assay characterisics must be solved/corrected.

 

Regards.

 

 

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Dear Colleagues

Our lab uses the Roche Total PSA assay (04491734190) and the kit insert states the following with respect to Limits and ranges [CLSI EP17-A]:

Measuring range 0.003 – 100 ng/mL

Lower detection Limit 0.003 ng/mL

Limit of Blank 0.006 ng/mL

Limit of Detection 0.014 ng/mL

 

At present we report our Total PSAs to one decimal place and report any results less than 0.1 as <0.1 ug/L.

[Our lowest IQC (BioRad Lyphochek) has a target value of 0.1 and runs with a CV of just under 6%]

 

We are getting an increasing number of requests to report down to much lower values.

 

I was wondering what other Roche users report down to? And indeed what users of other assays do?

 

Regards

Mark Lynch

Altnagelvin Hospital

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