This lesson from Jim's website might be helpful:
http://www.westgard.com/lesson29.htm
cheers
J
Dr Jonathan Middle
Deputy Director, UK NEQAS Birmingham
0121 414 7300, fax 0121 414 1179
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-----Original Message-----
From: Clinical biochemistry discussion list on behalf of Mainwaring-Burton Richard (RGZ)
Sent: Tue 01/04/2008 15:23
To: [log in to unmask]
Subject: sensitive issues
Pardon my ignorance all
I am struggling with the "sensitivity" of PSA and other similar assays.
We use Abbott Architect Total PSA - (data sheet : Functional
Sensitivity = 0.05, Analytical Sensitivity = 0.008)
Colleagues with Roche Modular - (data sheet : Functional
Sensitivity = 0.03, Analytical Sensitivity = 0.003)
We both currently default to <0.1 as lower limit of detection.
My questions for the clever guys (simplish answers please) are :
1. Are we being over cautious - could we claim a lower cut-off limit ?
2. What do I do when a Urologist has asked me to send the sample for an
"advanced" PSA for post radical prostatectomy monitoring ? I am concerned
that I may send the sample to someone using the same assays but different
rules! (Our Architect reported result of 0.00)
3. What are the REAL meanings of functional and analytical
sensitivities ? - I have read what it says in the data sheet, but would like
understandable translation please.
4. How do we translate those into a reasonable and justifiable lower
limit of detection ?
5. Yet again PSA - Provokes Stress and Anxiety.
with best wishes
Richard
Richard Mainwaring-Burton
Consultant Biochemist
Queen Mary's Hospital
Sidcup, Kent
020-8308-3084
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