The following link is to a 2016 public inquiry in Australia which arose from a reagent lot-to-lot change in PSA values leading to the inappropriate management of many post-prostatectomy patients.

 

http://www.sapathology.sa.gov.au/wps/wcm/connect/1fa1d43f-08ab-49e0-9875-369da73bc731/Final+Report+-+SA+PSA+Review+-+July+2016.pdf?MOD=AJPERES

 

It not only highlights the importance of assuring performance if very low levels of PSA are to be used for monitoring recurrence (and the potential consequences for everyone involved if there is an issue ), but points 69 – 73 of the report suggest it may also be worth confirming with the reagent manufacturer that their test is intended to be used for that purpose, even if the  package insert indicates it should be.

 

Eric

 

 

We report our total PSA assay results to 3 decimal places as this enables it to be used as a sensitive marker of recurrence for post-prostatectomy patients.

 

Finding a sample or control with low but detectable PSA is challenging.

 

However we found a CV% of 7.01% at a mean of 0.0213 ng/mL (n=10) using a patient sample.

 

We report down to 0.014 ng/mL.

 

Because we have no IQC at this level, we periodically rerun patient samples that have been aliquoted and stored frozen for several months.

 

We found good reproducibility between baseline results (at 0.015 – 0.025) from fresh samples and same sample rerun after being frozen and thawed.

 

David

 

 

 

This e-mail is covered by the disclaimer found at the end of the message.

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

This email is confidential and intended solely for the use of the individual to whom it is addressed. Any views or opinions presented are solely those of the author and do not necessarily represent the views of the Trust or organisation it was sent from.

If you are not the intended recipient, be advised that you have received this email in error and that any use, dissemination, forwarding, printing, or copying of this email is strictly prohibited. 

If you have received this email in error please contact the sender.

The content of this e-mail and any attachments or replies may be subject to public disclosure under the Freedom of Information Act 2000, unless legally exempt.

------ACB discussion List Information-------- This is an open discussion list for the academic and clinical community working in clinical biochemistry. Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content. ACB Web Site http://www.acb.org.uk Green Laboratories Work http://www.laboratorymedicine.nhs.uk List Archives http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html List Instructions (How to leave etc.) http://www.jiscmail.ac.uk/

********************************************************************************************************************

This message may contain confidential information. If you are not the intended recipient please inform the
sender that you have received the message in error before deleting it.
Please do not disclose, copy or distribute information in this e-mail or take any action in relation to its contents. To do so is strictly prohibited and may be unlawful. Thank you for your co-operation.

NHSmail is the secure email and directory service available for all NHS staff in England and Scotland. NHSmail is approved for exchanging patient data and other sensitive information with NHSmail and other accredited email services.

For more information and to find out how you can switch, https://portal.nhs.net/help/joiningnhsmail

------ACB discussion List Information-------- This is an open discussion list for the academic and clinical community working in clinical biochemistry. Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content. ACB Web Site http://www.acb.org.uk Green Laboratories Work http://www.laboratorymedicine.nhs.uk List Archives http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html List Instructions (How to leave etc.) http://www.jiscmail.ac.uk/