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vicliz

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Posts: 27
 #1 
I had my blood tests done through Quest.  Results came back with an ANA titer of 1:160 speckled pattern and  SM/RNP positive 2.7 BUT the SM antibody and RNP antibody tests were negative.  How can that be????

Vicki
Dolphin

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Posts: 50
 #2 
Hi Viki.  My range was 0-0.9 and I was at 0.9 for SM/RNP.  On the most basic ENA panel, they are measured separately as DS DNA, SM, RNP, SSA. However, the more complete profile test for additional antigens and includes the ratio SM/RNP. 
        If the SM/ RNP is +, this means you had a greater number of RNP than SM antibodies.   I read online (so it def might not be true) that this then can be subsituted for a  + RNP test, if RNP by itself was negative.  RNP is usually found in Mixed Connective Tissue Disease (MCTD), but occasionally SLE. Ultimately, however, it is up to ur rheumatologist however they choose to interpret this finding and if it is meaningfull given the negative SM, RNP. Do u have other + tests ?
upstater

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 #3 
My rheumatologist also mentioned the sensitivity of the tests being different and that she saw false positives sometimes with the one RNP test. And even then, there are different assays (I think that's the word).

So my SM/RNP result was <0.2. I also had RNP tested at another lab that was negative. But then as a part of a myositis panel, they also tested RNP with a different "assay" and it was 39.2. The reference range for that is:
Negative: < 20 EU/ml
Borderline/Equivocal: 20-25 EU/ml
Positive: > 25 EU/ml

I just know she said she'd run again at my next visit.

I did read some studies suggesting that RNP may also be associated with discoid lesions.
vicliz

Junior Member
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Posts: 27
 #4 
Dolphin,
My ANA speckled positive 1:160 and the sm/rnp 2.7 were the only tests pos.  All others negative.
Thanks to both of you for your reply.  It gives me more to ponder.  
Vicki
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