Anti DNA UK Criteria

[riannabri]

I had a test run in the UK for Anti DNA and for a positive result you had to be above >20 IU/ml although on contacting my USA doctor he said this is totally incorrect and that the following is what the rest of the world work too

anti-DNA antibodies are reported in IU/ml (international units per ml)

≤4 IU/mL Negative

5-9 IU/mLIndeterminate

≥10 IU/mL Positive

How can this be?

[Whathappned]

Interesting to know. Do they use the same lab test? I am aware there are different ones. Mine was only 10 the first time and I was classed as possible. The lab report said above 10 was positive below not. It didn't include 10 as anything and I have been in limbo since.

Luckily I got treat as if I had lupus and it's been a success.

[riannabri in reply to Whathappned]

As he says IU/ml (international units per ml) is what is uses all around the world, except in France where it is called UI OMS but its all the same

So the answer to your question is Yes if your test is reported in IU/ml it is as he says

≤4 IU/mL Negative

5-9 IU/mLIndeterminate

≥10 IU/mL Positive

In the UK they have done the same on Thyroid tests, so many underactive patients do not get treated

[Whathappned in reply to riannabri]

Thanks. I don't do to the hospital until April but they did bloods this week at my GP's. They are routinely adding this one LDH and CK every 6 months. I will ask for my results

[riannabri]

I still don't get that as my PCP states the Anti DNA if it is in IU/ML is run the same the world over. Here was his exact reply:-

UI OMS is French for units internationalle Org. Mondial de la Sante (our WHO). titre > 10 Ui OMS : Positif ) So the French just have a different name for the same units.

anti-DNA antibodies are reported in IU/ml (international units per ml) (again World Health Organisation should use all of the same reference ranges)

≤4 IU/mL Negative

5-9 IU/mL Indeterminate

≥10 IU/mL Positive

So I replied asking if my UK test states 25 and my USA test says 25 would that be the same and his reply was :-

Yes, they are the same thing, so >10 is positive for both but for some reason the UK (and Spain) use a reference range of >20

[Joy_1]

Hi

That is right it is not about the units of measurement it is about the sensitivity of the test. That is to say the type of method that is used. Some tests are more sensitive than others it just depends on what methodology is used. In this case I don't know what method is used or whether there are different methods.

What I would say is go with the person who is treating you, as we know RA does not hinge on 1 lone test result. And also as a disease changes over the years some test results change too.

[riannabri in reply to Joy_1]

I though a Positive anti-dsDNA test is specific to Lupus (SLE) only and distinguishes it from other autoimmune disorders?

I know a positive ANA can be uniform for many different Autoimmune Disease but my understanding was a Positive anti-dsDNA was a gold standard for lupus?

A little like a positive TgAb or TPO is specific to Thyroid Disease (Hashimotos) and cant be positive for any other reason

[AnnNY]

I was checked by my previous GP many times for anti-DNA. I had copies of his tests going back a few years. At that point my anti-DNA was for example 10 once, 9 once, and at the time this was considered negative. More recently, I was tested again from the same lab, and the ranges had changed to what you have written above. But now my anti-DNA was negative, for these ranges. I mentioned this to my rhumatologist said and she said, the earlier results were still negative. I do wonder about this, because sometimes they change their ranges because there is further knowledge. I thought about calling the lab and asking why the ranges were change, but I'm not sure it would have done any good. This was from the US, and off hand I don't remember which lab it was, just that I had seen them change their ranges. So it is still a bit of a mystery to me--one of many.