Author Topic: Antibody result grading system/s  (Read 1535 times)

Mtrasb

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Antibody result grading system/s
« on: June 30, 2020, 03:53:59 AM »
I got my antibody test results the other day and I scored positive with a result of 102, which is apparently "above high normal".

Yet after comparing with friends and family I am hearing about numbers that as low as 20's to numbers as high as 2000.

Are there multiple grading systems? What is the significance of this?

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Re: Antibody result grading system/s
« Reply #1 on: June 30, 2020, 08:19:26 AM »
Maybe a different scoring model? Perhaps positively negatively vs positively positively?

Offline biobook

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Re: Antibody result grading system/s
« Reply #2 on: June 30, 2020, 09:48:40 AM »
Which test did you take?  When I looked into this last month, it seemed that many tests were giving numerical results, but said that the results should be considered qualitative, that is, just interpreted as yes/no, you do/don't  have antibodies.
https://forums.dansdeals.com/index.php?topic=116518.msg2262364#msg2262364
But it's possible that there are newer tests that are considered quantitative, I don't know.

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Re: Antibody result grading system/s
« Reply #3 on: June 30, 2020, 11:00:58 AM »
There are several tests out there.  Each has their own scale.  So 1 tests numbers don't compare to another one.
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Offline justaregularguy

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Re: Antibody result grading system/s
« Reply #4 on: June 30, 2020, 11:58:06 AM »
my doctor grades the tests with a huge curve so you cant really judge from me
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Re: Antibody result grading system/s
« Reply #5 on: June 30, 2020, 12:22:50 PM »
I got my antibody test results the other day and I scored positive with a result of 102, which is apparently "above high normal".

Yet after comparing with friends and family I am hearing about numbers that as low as 20's to numbers as high as 2000.

Are there multiple grading systems? What is the significance of this?

According to Bikur Cholim 120 is borderline positive, above is positive etc....
I had test done at Labcorp, Result was positive for AB but didnt give numbers

Offline ckmk47

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Re: Antibody result grading system/s
« Reply #6 on: June 30, 2020, 12:47:43 PM »
According to Bikur Cholim 120 is borderline positive, above is positive etc....
I had test done at Labcorp, Result was positive for AB but didnt give numbers
Depends which test was used!
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Offline srap

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Re: Antibody result grading system/s
« Reply #7 on: June 30, 2020, 01:07:27 PM »
Qualitative vs Quantitative  Most labs are doing qualitative tests to see if a person has antibodies in their plasma which is in the blood sample they submit.  A qualitative test (think 'quality' of blood) yields an answer of either yes, positive, the amount of antibodies is above a preset threshold OR no, negative, the amount of antibodies is not above that preset threshold.  Hospitals and programs that want to acquire plasma to donate to patients want to make sure that the number of antibodies is sufficient for their purpose.  They need a quantitative test (think 'quantity') which yields a numerical result (see below) regarding antibodies, not just a '+' or '-'. 

The Meaning of Antibodies  Researchers still don't know what the number of antibodies means for the COVID-19 virus.  How high does a person's number have to be (ie, how many antibodies in the blood's plasma) in order for his immune system to protect him?  Does the number reduce over time?  Is the memory of having the antibodies enough to recreate them when called to duty in the future even though the number reduces?

Titers  Assigning the numerical value in a quantitative test is NOT a matter of counting the total number of antibodies in the plasma.  It is the counting of the last dilution of a blood sample where the antibodies are still detectable (at a predetermined concentration)!  If the blood is diluted 102 times and there are still antibodies in there, but there are not detectable antibodies in the next dilution, the quantitative result will be a titer of 102. A titer is the amount of a substance detectable in a solution.

Understanding Titer Numbers  The protocol for how many times to dilute a blood sample and then check for antibodies is determined by the lab/program.  Rather than checking every progressive dilution, they may find it more efficient to only check a handful of preset dilutions.   The Mt. Sinai plasma donation program, for example,  first checks at 80 dilutions.  If there is a concentration of at least 10% antibodies, then they check at 160 dilutions.  If there is no reaction in that dilution, ie less than 10% concentration of COVID-19 antibodies, then the person is said to have a titer of 80.  If there is a reaction at 160, they continue this process of checking at levels of 320, 960 and lastly 2880 dilutions.  Their titer would be at least 160, but would be higher if detected in progressive dilutions.  A person could potentially have a quantitative result of much higher than only 2880 dilutions, but since it is not tested they would never know.  2880 is the highest dilution of which I am aware.  I hope this clarifies why some people have numbers of 102, in the 200s or in the 2000s.

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Re: Antibody result grading system/s
« Reply #8 on: June 30, 2020, 07:15:28 PM »
@srap Do you know of other tests (eg: the Mayo Clinic test which seems to give a number up to around 5, or the one that gives a number where 15 is considered positive) also measure in titers aka the dilution system?
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Offline srap

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Re: Antibody result grading system/s
« Reply #9 on: July 01, 2020, 11:11:12 AM »
@srap Do you know of other tests (eg: the Mayo Clinic test which seems to give a number up to around 5, or the one that gives a number where 15 is considered positive) also measure in titers aka the dilution system?
A number of 15 being positive sounds like it could be the same system since Mt. Sinai uses 80 as a low positive that is just not strong enough for their purpose of donating plasma.  When I called Mayo clinic a while back they only had a qualitative test.  I can reach out to my liaison there and ask.

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Re: Antibody result grading system/s
« Reply #10 on: July 01, 2020, 11:12:23 AM »
A number of 15 being positive sounds like it could be the same system since Mt. Sinai uses 80 as a low positive that is just not strong enough for their purpose of donating plasma.  When I called Mayo clinic a while back they only had a qualitative test.  I can reach out to my liaison there and ask.
Thanks! Didn't you say Mt. Sinai's lowest number is 80? People I know who took this test got numbers like 3, 7, 8... (interesting that none of them were positive, unless those who were positive didn't care to check the fine print for a number!)
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