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  • Information on the Labcorp <0.014 PSA test

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    Old 03-04-2020, 10:18 AM   #1
    DjinTonic
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    Information on the Labcorp <0.014 PSA test

    Several Forum Brothers, here and elsewhere, have reported a Labcorp PSA result of <0.014. The < sign did not appear to be an error, but it wasn't clear what was going on. It appears this indeed was the lower limit of detection of their ultrasensitive test until just a few years ago. Some googling turned up this in a fairly well-known 2015 paper.

    Ultra-sensitive PSA Following Prostatectomy Reliably Identifies Patients Requiring Post-Op Radiotherapy (2015)

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4527538/

    Quote:
    PSA Follow-up
    All study patients had post-op ultrasensitive PSA (uPSA) performed. Prior to 2006 our lab ran the Beckman Coulter Access Hybritech PSA assay and from 2006 onwards used the Roche electrochemiluminescence ‘Elecsys’ immunoassay run on a Roche Modular E170. The reported lower limit of detection (analytical sensitivity) of the Hybritech assay is approximately 0.005 ng/mL and 0.014 ng/mL for the Roche assay, whereas the functional (biologic) sensitivities are approximately 0.007 and 0.030 ng/mL, respectively. For all patients the lab reported a uPSA threshold at 0.01 ng/mL.
    [Emphasis mine]

    In fact, the sample Labcorp uPSA test at the walkinlab.com site:

    https://www.walkinlab.com/products/view/prostate-specific-antigen-psa-ultrasensitive-blood-test

    is evidently an old one never updated: it has a 2015 copyright at the bottom and a (slightly different!) sample result: <0.015

    We know that Labcorp's uPSA test in most cases now measures down to 0.006. (From other sources, it appears that the ROCHE assay itself can detect to 0.002 or 0.003 depending on the analyzer, but Labcorp chooses not to push it or doesn't regularly use analyzers in that category.)

    Evidently some Labcorp facilities are still using analyzers with the older lower limit of 0.014.

    Note that Labcorp themselves nowhere states the lower limit of detection of its uPSA test, so they are free to change it (or, presumably, use multiple values depending on the analyzer) without notice. We can only surmise the LLD by seeing actual lab reports that have a specific value with the < sign.

    Djin
    __________________
    69 yr at Dx, BPH x 20 yr, 9 (!) neg. Bx, PCA3-
    7-05-13 TURP for BPH (90→30 g) path neg. for PCa, then 6-mo. checks
    6-06-17 Nodule on R + PSA rise on finasteride: 3.6→4.3
    6-28-17 Bx #10: 2/14 cores: G10 (5+5) 50% RB, G9 (4+5) 3% RLM
    Nodule negative for PCa. Bone scan, CTs, X-rays: neg.
    8-7-17 Open RP, neg. frozen sections, Duke Regional Hosp.
    SM EPE BNI LVI SVI LNI(5L, 11R): negative, PNI+, nerves spared
    pT2c pN0 pMX, G9 (4+5) 5% of prostate (4.5x5x4 cm, 64 g)
    Dry; ED OK with sildenafil
    11-10-17 Decipher 0.37 Low Risk; 5-yr met risk 2.4%, 10-yr PCa mortality 3.3%
    LabCorp uPSA: 0.010 (3 mo.)…0.015 (1 yr. 6 mo.)…0.015 (2 yr. 4 mo.)

     
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    Old 03-04-2020, 10:52 AM   #2
    hmcg7
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    Re: Information on the Labcorp <0.014 PSA test

    Thank You for the info, I will continue to work on the different lower thresholds from the lab and hopefully my Doctor.

     
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    Old 03-24-2020, 03:39 PM   #3
    NYCGMAN
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    Thumbs up Re: Information on the Labcorp <0.014 PSA test

    Boy, does this make me feel better. My recent Labcorp test result came back at <.014. I thought I was having a 133% increase in my previously undetected PSA. I've been very fortunate to be undetectable for 7 & 1/2 years but with a more risky pathology (intraductal), I've had a couple of minor PSA anxiety concerns along the way.

    Dr. Tewari changed hospitals after a few years, and so a different lab did the tests with <.00 as the new lower limit. He reassured me that <.00 was undetectable just like <.008.

    One time a life insurance physical reported a PSA of .06. I rushed to Dr. T's office and asked for a test. Result came back as <.02. After talking to the three nurses on duty I learned that their lab sometimes does the test with <.00 as the lower limit and sometimes <.02 is the lower limit. They couldn’t explain why, or predict when the .00 or .02 test would be used. For future visits i pressed for the lower limit. But I got <.02. But then a physical in FL and a new lab had me at <.006! Back up to NY for my annual Tewari visit and their lab changed to Labcorp and I continued at <.006. Then in March of 2019 I made the mistake of getting my physical lab work done by Quest and back to <.02. So I vowed to never return and this year went to Labcorp only to find <.014. After a number of hours researching ultrasensitive PSAs, here I am.

    Thank you so much for your careful research and reporting it to the rest of us. This is my first post on this site, but used to participate on the board that is now defunct and remember your numerous updates and sites for new research.

    1/22/13 <.008
    3/15/13 <.008
    6/21/13 <.008
    9/25/13 <.008
    12/13/13 <0.00
    4/11/14 <0.00
    10/17/14 <0.00
    6/12/15 <.02
    9/3/15 =.06
    10/12/15 <.02
    12/11/15 <.02
    3/18/16 <.006
    3/25/16 <.02
    6/17/16 <.02
    3/15/17 <.006
    6/16/17 <.006
    3/15/18 <.006
    5/25/18 <.006
    3/27/19 <.02
    6/7/19 <.006
    3/20/20 <.014
    __________________
    Age at diagnosis 63, DRE Normal, Dr. Tewari; 1/11, PSA 6.96; 2/11 49 core biopsy, Gleason 6, 2% in 1/3 cores, Gleason 6, 5% in 1/3 cores; Active Surveillance, Genetic Testing neg; 10/11, 52 core biopsy, Gleason 6, 5% in 1/3 cores; 10/12 PSA 10.09, PCA3 284; 12/12 Robotic Surgery: pT2c, organ confined, 10% of prostate, Gleason 7(3+4), w/ microscopic mucinous change and focal intraductal extension, neg margins

     
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    Old 03-26-2020, 10:22 AM   #4
    Michael F
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    Re: Information on the Labcorp <0.014 PSA test

    TY Dj! Great Detective work.

    I went back and looked at my early uPSA Lab Reports from LabCorp. My first was in Oct, 2012. All 23 to date have been analyzed in Birmingham, AL using Roche ECLIA methodology. ("Same Lab Using Same Methodology Each Time!")

    The Reference Interval is listed as: 0.000 - 4.000 ng/ml There has never been a Lower Limit of Detection listed.

    Several years ago I had telephone conversation with a Pathologist at LabCorp who suggested that the uPSA results should fall within a range of 2 Standard Deviations from the Mean.

    In my series of results that translates to: 0.023 +/- 0.008 ng/ml.

    Back then I located an article from a lab tech trade journal that stated the LLD for this uPSA Methodology was 0.007 ng/ml. Again, nowhere does Labcorp provide an LLD value.

    Thus, we strongly advocate to dump the 3rd decimal value by rounding to the 2nd decimal.

    What is most important for those monitoring for early warnings of BCR, is to never make a decision based solely on a value that appears in the 3rd decimal. The 3rd decimal values are Trillionths of a Gram Instead, establish a PSA level that, if/when reached, will trigger SRT. uPSA serves well as an early warning system for approaching BCR. The Rate of Increase is the most important factor.

    MF
    __________________
    PSA: Oct '09 = 1.91, Oct '11 = 2.79, Dec '11 = 2.98 (PSA, Free =13%)
    Jan '12: Biopsy: 1/12 = G7 (3+4) & 5/12 = G6
    March '12: Robotic RP: Left: PM + EPE => MD excised additional adjacent tissues
    Pathology: Gleason (3+4) pT3a pNO pMX pRO c tertiary pattern 5 / Prostate Size = 32 grams / Tumor = Bilateral: 20% / PNI: present
    uPSA Range: 0.017 - 0.032 at 94 Months Post Op: Mean = 0.023 (n = 23)
    LabCorp: Ultrasensitive PSA: Roche ECLIA
    Continence = Very Good (≥ 99%) ED = present

     
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    Old 03-26-2020, 12:24 PM   #5
    DjinTonic
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    Re: Information on the Labcorp <0.014 PSA test

    Just a note. The Reference Interval does NOT refer to a test's range of detection. Perhas it's the range for which the test is suggested for use.

    See this page for the lowest limit for PSA I have seen for a Roche assay: 0.002.

    https://diagnostics.roche.com/in/en_gb/products/params/elecsys-total-psa-and-free-psa.html

    Djin
    __________________
    69 yr at Dx, BPH x 20 yr, 9 (!) neg. Bx, PCA3-
    7-05-13 TURP for BPH (90→30 g) path neg. for PCa, then 6-mo. checks
    6-06-17 Nodule on R + PSA rise on finasteride: 3.6→4.3
    6-28-17 Bx #10: 2/14 cores: G10 (5+5) 50% RB, G9 (4+5) 3% RLM
    Nodule negative for PCa. Bone scan, CTs, X-rays: neg.
    8-7-17 Open RP, neg. frozen sections, Duke Regional Hosp.
    SM EPE BNI LVI SVI LNI(5L, 11R): negative, PNI+, nerves spared
    pT2c pN0 pMX, G9 (4+5) 5% of prostate (4.5x5x4 cm, 64 g)
    Dry; ED OK with sildenafil
    11-10-17 Decipher 0.37 Low Risk; 5-yr met risk 2.4%, 10-yr PCa mortality 3.3%
    LabCorp uPSA: 0.010 (3 mo.)…0.015 (1 yr. 6 mo.)…0.015 (2 yr. 4 mo.)

     
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