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Does increasing Normal ASO titer mean infection?


philamom
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I would love to know the answer to this one. I have been told that an ESR level is a daily marker of active inflammation anywhere in the body. If the rising titer was due to infection this would possibly show it. I was also told to follow my son's CRP level for the same reason - this one is to be done monthly. I am sorry that I do not know the full names for these tests - perhaps someone else reading this can help.

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My dd9 is in the category of always having normal ASO/D-NASE titers, but her recent blood test shows an increase in ASO (but still normal). Is this just due to exposure, not infection?

 

ASO= Nov-17, Dec-17, August-48

 

D-NASE= Nov-60, Dec-120, August-60

 

The Dnase in December would indicate a potential infection in September/October. The low ASO is pretty meaningless as it is less than one dilution apart. I'll explain below:

 

 

First, to compare results you need to use the same laboratory and test procedure. Generally a positive rise is defined as > than a 2 dilution rise. This means that if you measured 1:60 when convalescent and later 1:120 you would be considered to have a positive rise. The dilutions are typically: 1:60, 1:85, 1:120, 1:170, 1:240, 1:340, 1:480, 1:680, 1:960, 1:1,360, 1:1,920, and 1:2,720.

 

Numbers that fall inbetween can be done by individual labs but aren't standardized. Numbers under 60 are outside the sensitivity of the typical measurement system (although you might want to check your particular lab). Basically, I'm saying they can't tell you very much about your ASO because it is below 60 (the first dilution).

 

So for what you posted, the anti-DnaseB would be considered a rise indicating that there was a likely infection in late September. It is not surprising that the ASO would not rise.

 

In terms of what your doctor will say, he/she will likely say both are "normal" despite the rise (because most doctors don't know that rise is more important than absolute value).

 

The CDC back in 1971 set the upper limit of normal http://www.ncbi.nlm.nih.gov/pmc/articles/PMC377331/ for school-age kids of: school age, ASO = 170; ADNB of 170.

 

Kaplan from the world health organization did a broader study in 1998 http://pediatrics.aappublications.org/cgi/content/abstract/101/1/86 and found the ULN for their sample to be 240 for ASO and

640 for AntiDNAseB. Many laboratories (including the Mayo clinic) use an ULN of 400 for ASO.

 

Bottom line is that rise is more important than absolute value. If you don't have a prior reading you are forced to use ULN. To compare for rise, you must use the same laboratory and equipment/test. A rise must be two dilutions apart to avoid experimental error.

 

Regards,

 

Buster

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Okay, for the way more than you wanted to know camp :unsure:

 

see http://jcm.asm.org/cgi/content/abstract/35/4/839 for the different types of measurement procedures for ASO

 

The basic approaches are:

  • Toraysphere
  • Rantz-Randall
  • NA-Latex-ASL method

 

Each of these methods has a variety of false positives (FP) and false negatives (FN) even for a perfect sample.

 

The most useful measures compare True Positives (TP) to false positives(FN):

  • positive predictive value -- how likely a positive is a true positive (TP/(TP+FP))
  • negative predictive value -- how likely a negative is a true negative (TN/(FN + TN))

 

In terms of the above tests, the tests have:

  • Toraysphere - 81% PPV, 79% NPV
  • Rantz-Randall - 67% PPV, 62% NPV
  • NA-Latex-ASL method - 76% PPV, 69% NPV

 

However, the most important factor is that if the blood sample is taken at the wrong time then there isn't any ASO in the blood to test for.

 

Undoubtely more than you wanted to know -- but the importance is that > 30% of cases will have false negatives even on very good samples.

 

Buster

 

 

First, to compare results you need to use the same laboratory and test procedure.

Edited by Buster
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My dd9 is in the category of always having normal ASO/D-NASE titers, but her recent blood test shows an increase in ASO (but still normal). Is this just due to exposure, not infection?

 

ASO= Nov-17, Dec-17, August-48

 

D-NASE= Nov-60, Dec-120, August-60

 

The Dnase in December would indicate a potential infection in September/October. The low ASO is pretty meaningless as it is less than one dilution apart. I'll explain below:

 

 

First, to compare results you need to use the same laboratory and test procedure. Generally a positive rise is defined as > than a 2 dilution rise. This means that if you measured 1:60 when convalescent and later 1:120 you would be considered to have a positive rise. The dilutions are typically: 1:60, 1:85, 1:120, 1:170, 1:240, 1:340, 1:480, 1:680, 1:960, 1:1,360, 1:1,920, and 1:2,720.

 

Numbers that fall inbetween can be done by individual labs but aren't standardized. Numbers under 60 are outside the sensitivity of the typical measurement system (although you might want to check your particular lab). Basically, I'm saying they can't tell you very much about your ASO because it is below 60 (the first dilution).

 

So for what you posted, the anti-DnaseB would be considered a rise indicating that there was a likely infection in late September. It is not surprising that the ASO would not rise.

 

In terms of what your doctor will say, he/she will likely say both are "normal" despite the rise (because most doctors don't know that rise is more important than absolute value).

 

The CDC back in 1971 set the upper limit of normal http://www.ncbi.nlm.nih.gov/pmc/articles/PMC377331/ for school-age kids of: school age, ASO = 170; ADNB of 170.

 

Kaplan from the world health organization did a broader study in 1998 http://pediatrics.aappublications.org/cgi/content/abstract/101/1/86 and found the ULN for their sample to be 240 for ASO and

640 for AntiDNAseB. Many laboratories (including the Mayo clinic) use an ULN of 400 for ASO.

 

Bottom line is that rise is more important than absolute value. If you don't have a prior reading you are forced to use ULN. To compare for rise, you must use the same laboratory and equipment/test. A rise must be two dilutions apart to avoid experimental error.

 

Regards,

 

Buster

 

Buster..does the same hold true for myco p..

 

a reading in mayish was 1.60 another draw 3 weeks ago was 1.79 (above .90 igg could be positive)

dan doc said no worry...margin or error..and these numbers can fluctuate...

however..in last week we have motor tics which were 90% other than times of stress or a specific trigger..

how much time should go by before another draw...??

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