Labs Completely Different From 2 Different Labs? One + One -

[StephanieL]

Has anyone had this happen?

 

We had one test 2 weeks ago with <10 tTG  (<20 is negative)

 

ONE WEEK LATER- different lab  tTG of 25 (<20 is negative)

 

 

Nothing changed. Nothing unusual. Nothing new. 

 

 

 

 

 

[nvsmom]

I have had that happen only with TSH testing, and the doctors always (and in my case, wrongly) went with the normal result. They don't seem to believe in "best 2 out of 3". LOL

No wait, I once had my tTG IgA tested about a month apart and the results differed by almost 20 points. At the time I had been gluten-free for close to a year, but the results were both in the positive range.

Your body is not static and tests do not always correlate to what is happening in the body. Definitely confusing.

What is the doctor saying?

[StephanieL]

No one has a clue as far as they are telling me.  

 

This is for my DS- 

 

I feel like I can't trust these labs anymore. These labs and poor growth sent us to major Celiac player. As I said- 2 weeks apart but processed at different labs with totally differing results?  It's making me completely crazy. I have had iron test for donating blood where one finger is low then the other is okay so I do understand fluctuations but for one to be <10 (non detectable) and the other positive?  

[GottaSki]

Did he have any other celiac antibody test?

The DGPs should be included with initial along with follow up blood work.

[IrishHeart]

Lab results may vary from lab to lab. The interpretation of results will also vary in ranges.

 

You should always have blood tests drawn from the SAME lab.

 

This is my celiac doc's opinion.  I agree. I have seen some things fluctuate erratically in just a few weeks,.(all wrong, therefore)

 

For example, It can also be changed if you are fasting. (this is not relevant to the test you mean right now, of course)

 

No one seems to know this, but labs will vary on glucose readings and the  TSH for thyroid, etc, if you have eaten or not.

[SMRI]

If they get the right side of the slide vs the left side of the slide and how the smear was done, the results can vary.  That is why there is often such a huge range of "normal" for blood work.  Also, your blood contents are not static, maybe that one pump just didn't have the same amount in it?  Also, how good is the person doing the tests.  In my repeat TgA test, varied but 5 parts, same lab, two days apart???  Yes, you have more of a range, but how much gluten was he eating in that two week span, etc, etc, etc.  Maybe you can sit down with the lab tech at your dr's office and see how they run the samples and talk to them why they vary so much from reading to reading.

[StephanieL]

There was no gluten ingested in the week and a half. We were told to go to Mayos lab by one of the top Celiac Dr's in the world. We aren't talking the difference between a few points. At MINIMUM we're talking 15 points different. Now I'm pretty up on things and that margin of error seems unusually hight to me when the specificity of the test is so high. I can't talk to the tech who did the test. They don't give that information out to people.

Any of you have documentation supporting the ideas that specifically with the tTG, there is that wide a margin of error? I'm more than happy to entertain those ideas if there is something to back it up.

None of his blood work has been fasting.

[GottaSki]

There was no gluten ingested in the week and a half. We were told to go to Mayos lab by one of the top Celiac Dr's in the world. We aren't talking the difference between a few points. At MINIMUM we're talking 15 points different. Now I'm pretty up on things and that margin of error seems unusually hight to me when the specificity of the test is so high. I can't talk to the tech who did the test. They don't give that information out to people.

Any of you have documentation supporting the ideas that specifically with the tTG, there is that wide a margin of error? I'm more than happy to entertain those ideas if there is something to back it up.

None of his blood work has been fasting.

Here is the problem..in my opinion. Many of us encounter lab inconsistencies, but we are not actively publishing our results. The results that are published with regard to celiac are performed in controlled settings of the best celiac centers in the world.

In your situation, I would push for a third and if you have only run tTG....I would add the balance of the celiac antibody panel.

Again...all my opinion based on years of reading published journals and trying to match that information to my family's testing experience along with the many members here whom post their less than textbook results.

[SMRI]

There was no gluten ingested in the week and a half. We were told to go to Mayos lab by one of the top Celiac Dr's in the world. We aren't talking the difference between a few points. At MINIMUM we're talking 15 points different. Now I'm pretty up on things and that margin of error seems unusually hight to me when the specificity of the test is so high. I can't talk to the tech who did the test. They don't give that information out to people.

Any of you have documentation supporting the ideas that specifically with the tTG, there is that wide a margin of error? I'm more than happy to entertain those ideas if there is something to back it up.

None of his blood work has been fasting.

 

Lab tests in general have a wide range of normal. It's not my "idea", it just is what it is. Look at the ranges for past blood work.   Also, looking at my own lab results from Mayo <20 is negative, but positive is >30 for the IgG, so, even if the numbers above differ, interpretive data is the same...it's not a positive.   My results  

Open Original Shared Link

June 20, 2014

66.5 U 

 

 

Open Original Shared Link

<20.0 (Negative) U

Interpretation: Positive (>30.0)

 

This is my IgA total, the wide range of normal shown:  

Open Original Shared Link

June 20, 2014

205 mg/dL

 

 

Open Original Shared Link

61 - 356 mg/dL  

 

Open Original Shared Link

June 20, 2014

23.5 U 

 

 

Open Original Shared Link

<20.0 (Negative) U

Interpretation: Weak Positive (20.0-30.0)

This is a weak positive--but since all of my other results came back positive, including biopsy and genetic testing, it doesn't really matter......but, if that is the ONLY test you are looking it, it's going to cause confusion.

 

 

There is also the question of the quality of the person conducting the lab and the actual sample itself.  Again, talk to a lab tech somewhere, they will explain it to you.  What do the doctors say?

[GottaSki]

Lab tests in general have a wide range of normal. It's not my "idea", it just is what it is. Look at the ranges for past blood work. Also, looking at my own lab results from Mayo <20 is negative, but positive is >30 for the IgG, so, even if the numbers above differ, interpretive data is the same...it's not a positive. My results

Open Original Shared Link

June 20, 2014

66.5 U

Open Original Shared Link

<20.0 (Negative) U

Interpretation: Positive (>30.0)

This is my IgA total, the wide range of normal shown:

Open Original Shared Link

June 20, 2014

205 mg/dL

Open Original Shared Link

61 - 356 mg/dL

Open Original Shared Link

June 20, 2014

23.5 U

Open Original Shared Link

<20.0 (Negative) U

Interpretation: Weak Positive (20.0-30.0)

This is a weak positive--but since all of my other results came back positive, including biopsy and genetic testing, it doesn't really matter......

There is also the question of the quality of the person conducting the lab and the actual sample itself. Again, talk to a lab tech somewhere, they will explain it to you. What do the doctors say?

I don't understand your point.

Yes, lab ranges differ and there are wide ranges of normal.

[SMRI]

I don't understand your point.

Yes, lab ranges differ and there are wide ranges of normal.

The OP wanted me to back up the info that there is a wide range of normal in labs and results do differ from lab to lab....and the interpretive data of her 2 tests is the same, not positive.

[StephanieL]

There is a range of normal. Sure. But how do 2 tests 10 days apart show negative results and positive results.  

[SMRI]

Again..differences in lab quality, sample quality, technician quality, etc, etc, and if the second lab was the Mayo lab, it is not positive...

[StephanieL]

It would be a weak positive at Mayo but that was the local (also known around the country).  Which it shouldn't be after 4 years gluten-free. Which is why we went to the top Doc and all that jazz.

[beth01]

If you took a blood sample to Lab A and they run a platelet count 20 times they should get roughly the same answer 20 times, give or take a few points.  You could then take the same sample to Lab B and they have a different analyzer that uses just a little different methodology in determining a plt count and run the sample through 20 times, you should still be getting roughly the same answer but it won't necessarily be the same answer the first lab gave you. Same with any other analyte.

 

There are also a lot of variables, sample quality( if the person drawing your blood had a hard time, that can effect the quality), quantity can be an issue, sometimes there are bubbles on the top of the sample that the analyzer aspirates giving false results, or sometimes a specimen is mislabeled.  It happens.

 

Are you talking a IgA tTg?  Mine was run at Mayo and my reference range is <4 is considered negative.

 

I would worry more if it was the same lab giving you varying results.  Always have them done if possible at the same lab.

[StephanieL]

But if lab A and lab B are using the same test for the same thing- shouldn't the results be similar? Perhaps a few points off but a compleat negative vs. a positive?

Also I realize in a perfect world all the labs would be done at the same place but the reality is that Dr's change, insurance changes, labs covered change and that's life. There are standards for labs I assume so that if it's the same test and the same method the results should be similar.

How many people are walking around thinking they have positives from one lab and they really aren't?

[SMRI]

But if lab A and lab B are using the same test for the same thing- shouldn't the results be similar? Perhaps a few points off but a compleat negative vs. a positive?

Also I realize in a perfect world all the labs would be done at the same place but the reality is that Dr's change, insurance changes, labs covered change and that's life. There are standards for labs I assume so that if it's the same test and the same method the results should be similar.

How many people are walking around thinking they have positives from one lab and they really aren't?

 

A lot of lab testing is subjective though--they look at a slide and count how many whatever's they see--so if they have a sample that isn't a very good sample--they don't see everything, thus the wide range of normal. Then, your blood isn't equally saturated with the enzymes or whatever so, if they have a sample that is on the lower end of that, like your first test I suspect, the numbers are going to vary.  There are reasons they do more than one test to confirm and if the numbers are borderline like your numbers, it would be prudent to do more testing.  Have you had the full panel run and if so, what were those numbers?  How about a biopsy, what did that say?  Genetic testing??  If your numbers came back at 120, probably don't need more testing for a firm positive, but when neither of your lab results are a firm positive, then you move on to the next round.  You are trying to make the lab test and exact test/numbers and they just are not.  So, now it's time to move on and either do more testing or look for another cause.

[RMJ]

I used to develop tests for antibodies. They are not perfect. Run the same sample twice and the numerical results will be off by a bit. If a different person runs the test, or it is run on a different day, the results will be further off. I looked at information on the FDA website for one manufacturer of celiac DGP tests. When two different tests manufactured by the same company were compared, 217 out of 228 samples gave the same result (both positive or both negative). So 11 of 228 samples were positive on one test and negative on the other.

[beth01]

Lab A and Lab B are testing for the same antibody but not necessarily using the same testing equipment.  It would be like saying traveling 800 miles by car is the same as traveling 800 miles by plane because you are in a vehicle, not taking into account the mode of transportation or time.  I really can't explain why the lab results are varying so much, I just know what can happen in labs to cause a large variance. Some is human error and some is specimen quality.  Unfortunately not 100% of lab tests can be correct 100% of the time.

[RMJ]

How many people are walking around thinking they have positives from one lab and they really aren't?

Several percent of the people tested. That is what it means to have a specificity of 96 or 97%. It is not accurate 100% of the time.

[GottaSki]

How many people are walking around thinking they have positives from one lab and they really aren't?

I worry more about the incorrect negative....while getting a positive in error is very disconcerting, at least a person with celiac disease would know to investigate more....while the person with many non-specific symptoms would cross celiac disease as a possibility : (

Have you decided to retest?

Also, maybe I missed...did he have positive or even high normal DGP..either IgA or IgG?

Hang in there!!!

[SMRI]

I worry more about the incorrect negative....while getting a positive in error is very disconcerting, at least a person with celiac disease would know to investigate more....while the person with many non-specific symptoms would cross celiac disease as a possibility : (

Have you decided to retest?

Also, maybe I missed...did he have positive or even high normal DGP..either IgA or IgG?

Hang in there!!!

 

Neither test is a conclusive positive though so I don't know that the "negative" test is incorrect really.  

[StephanieL]

One Dr. wants a minimum 4-8 week challenge with scope at the end.

 

One said with an initial (4 +years ago) tTG of 122 with it falling to 78 after 6 months and continuing to fall that it is Celiac and even without a + biopsy we can be sure it's Celiac and to carry on.

 

No one can give me information on the variation in the tests.

[GottaSki]

One Dr. wants a minimum 4-8 week challenge with scope at the end.

 

One said with an initial (4 +years ago) tTG of 122 with it falling to 78 after 6 months and continuing to fall that it is Celiac and even without a + biopsy we can be sure it's Celiac and to carry on.

 

No one can give me information on the variation in the tests.

If symptoms are continuing gluten-free...I'd vote for endoscopy WITHOUT challenge. I had four annual endos until celiac biopsies finally improved. If he doesn't have symptoms I would simply carry on and wait for his next annual antibody panel.

Hang in there!

[StephanieL]

Except for the continued elevation in the tTG's and the fact that he's skin over bones, he's great.  

 

We are leaning towards do nothing now. There are logistics to doing a challenge.  

 

Lisa, I said this exact thing to them. I feel like a challenge has us jumping from A to C completely missing any information from step B ( which is kid 4+ years on gluten-free diet).  They don't seem to see this as an issue.