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Main Forums => Living With HIV => Topic started by: _dave_ on January 06, 2013, 01:59:18 pm

Title: Viral Load Results: What does "TND" mean?
Post by: _dave_ on January 06, 2013, 01:59:18 pm
Hello people!

My name is Dave , I am from Argentina. I ve been diagnosed positive back in December 2009 and ever since I am under medical treatment. A few months after getting the treatment, my HIV viral load was undetectable.

Last December 2012 I got tested like I normally do every 3 months or so. My viral load results were "target not detected" .

What does that mean? Has anyone ever gotten that result? At first I thought it might be an error with the test itself. But I searched the internet and realized that this is a possible result that people when they get their viral load done.

I already have an appointment with my doctor for February 8th, but I keep wondering and thinking over and over again what that could mean.

So if anyone knows or anyone ever got a result like that, plz comment :)
Title: Re: Viral Load Results: What does "TND" mean?
Post by: spacebarsux on January 06, 2013, 02:16:15 pm
Last December 2012 I got tested like I normally do every 3 months or so. My viral load results were "target not detected" .

Hi Dave, to me it sounds like a roundabout way of saying undetectable. If some one knows better perhaps they could shed some light.
Title: Re: Viral Load Results: What does "TND" mean?
Post by: _dave_ on January 06, 2013, 02:28:26 pm
Hi! Thanks for your reply !

That's exactly what I thought . The only detail is that I've been undetectable for a pretty long time and never got that result.

These are the last 3 results from the last tests that I got done:

March 1st, 2012
Viral Load: < 20
(undetectable)

August 6th, 2012
Viral Load: < 20
(undetectable)

December 20th, 2012
Viral Load: "target not detected"

________________

So, on all of my viral load results I get either a number or something like ">20" or ">50" . Why did I get "Target Not Detected" on this one? My viral load has been tested since 2009 and its the first time that I got that result .

Title: Re: Viral Load Results: What does "TND" mean?
Post by: eric48 on January 06, 2013, 04:53:17 pm
Hi,

I was trying to get some explanation from the biologist the other but she only know the one unit that she uses.

Multiple PCR is a repetitive amplification.

By Chance (contamination) or error at some point of the sequence a 'noise' signal can enter. Say : 1 enter at step X

If there are 20 iterations, you get a reading of (20-X), but since X is not known you can not say for sure if a hit means 5 or 10 or 19

In this case the 'technical reading' is : detectable but under the limit of quantication (20 in case of Cobas Taqman 2.0) , the biologist may report:
either:
- detectable but under the limit of quantication (because this is what the instrument says)
OR
- <20 (becuas ethat is what doctors want to know)

If there is NO hit

 the biologist may report:
either:
- target not detected (because this is what the instrument says)
OR
- <20 (because ethat is what doctors want to know)

reporting TND ( aka Strictly UD ) or not (and reporting <20 instead) therefore depends on the bilogist pratice.

My 'hospital' lab biologist (once a year) reports TND as TND
My 'commercial' lab biologists (other blood draw) reports TND as <20 (not matter what the reading is...) . She said this is her current practice for HIV. She , BTW, mentioned that in case of TB (also measured on Cobas) they will opt for reporting TND in case it is TND

I 'think' one practice is more 'scientific' and the other more practical for patient management as some patient 'might' understand TND as meaning 'Virus free' (*) and quit treatment. (*) which is untrue because the studied sample is only a very tiny drop of the blood sample, so the virus may be in another portion of the blood sample

In a recent article an hospital reported that about 30% of their 'long term' follow ups where technically 'SUD' (or TND, if you wish), but failed to related to anything 'clinical'

So I think there are different ways or reporting very low signals.
Not all biologists, hospital and even instruments report exactly the same.

For the sake of cohort studies, the lowest strata commonly used is <50 so that methological issues do not interfere with statistics

At least this is my understanding as of today since I could not get really explicit answers neither from my doc not from the 'commercial' lab biologist.
I have asked my doctor if it would be possible to arrange a conversation with the hospital biologist to get a clearer idea, but, as of today I have made no progress on this point (which my doctor waived away as being pointless...)

Hope this helps

Eric   


 
Title: Re: Viral Load Results: What does "TND" mean?
Post by: _dave_ on January 06, 2013, 09:41:50 pm
Hi,

I was trying to get some explanation from the biologist the other but she only know the one unit that she uses.

Multiple PCR is a repetitive amplification.

By Chance (contamination) or error at some point of the sequence a 'noise' signal can enter. Say : 1 enter at step X

If there are 20 iterations, you get a reading of (20-X), but since X is not known you can not say for sure if a hit means 5 or 10 or 19

In this case the 'technical reading' is : detectable but under the limit of quantication (20 in case of Cobas Taqman 2.0) , the biologist may report:
either:
- detectable but under the limit of quantication (because this is what the instrument says)
OR
- <20 (becuas ethat is what doctors want to know)

If there is NO hit

 the biologist may report:
either:
- target not detected (because this is what the instrument says)
OR
- <20 (because ethat is what doctors want to know)

reporting TND ( aka Strictly UD ) or not (and reporting <20 instead) therefore depends on the bilogist pratice.

My 'hospital' lab biologist (once a year) reports TND as TND
My 'commercial' lab biologists (other blood draw) reports TND as <20 (not matter what the reading is...) . She said this is her current practice for HIV. She , BTW, mentioned that in case of TB (also measured on Cobas) they will opt for reporting TND in case it is TND

I 'think' one practice is more 'scientific' and the other more practical for patient management as some patient 'might' understand TND as meaning 'Virus free' (*) and quit treatment. (*) which is untrue because the studied sample is only a very tiny drop of the blood sample, so the virus may be in another portion of the blood sample

In a recent article an hospital reported that about 30% of their 'long term' follow ups where technically 'SUD' (or TND, if you wish), but failed to related to anything 'clinical'

So I think there are different ways or reporting very low signals.
Not all biologists, hospital and even instruments report exactly the same.

For the sake of cohort studies, the lowest strata commonly used is <50 so that methological issues do not interfere with statistics

At least this is my understanding as of today since I could not get really explicit answers neither from my doc not from the 'commercial' lab biologist.
I have asked my doctor if it would be possible to arrange a conversation with the hospital biologist to get a clearer idea, but, as of today I have made no progress on this point (which my doctor waived away as being pointless...)

Hope this helps

Eric

Thanks for that information! That's kinda what I read online.

I will have an appointment in February so thats going to be the first thing Im gonna ask my doctor about those test results and of course I will share that info here :D