Question:
We use a different lab for our thyroid panels, and very often the clients have thyroid peroxidase and thyroid anti TPO results that are far higher than the reference ranges on the ODX application. The results we have are IU/L and your units are KIU/l. Can you shed some light on this?
Answer:
We are aware that the ranges for thyroid antibodies show considerable variability between labs. I have had conversations with researchers at more than one of these labs as we have had a number of users bring this to our attention.
Thyroid Peroxidase
Thyroid Peroxidase Abs tend to show less variability, which is why we can accommodate the differences in standard ranges between labs. Best bet is to check and see if your lab is available from the drop down. If so, please enter the result and the range on the report should match the range on your original lab result.
If your lab is not in the system then we recommend choosing either Quest or LabCorp as the lab, even though it isn't your lab!
The best bet is to look at the range from your lab and choose either the Quest or Labcorp biomarker based on a similar range.
For instance, your lab uses a reference range of <34 IU/ml for their Anti-TPO biomarker result. This is the same as LabCorp, so choose LabCorp as the lab, and this range will be used in the analysis reports.
If your lab's standard range is more in line with 0 - 9, which is Quest's range, choose Quest as the lab, and this range will be used in the software.
Thyroglobulin Antibodies
The Thyroglobulin Antibody result is another result that has discrepancies from lab to lab. Quest and LabCorp, the 2 largest reference labs here in the U.S. are the labs we use for our default units and reference ranges for Thyroglobulin Antibodies in the ODX application: 0 - 1 IU/ml
The discrepancy between labs such as Cleveland Heart Lab, Lifelabs in Canada, and Vibrant America comes about because these labs (and other labs across the globe) are using a different analytical system to measure the presence of Thyroglobulin Antibodies.
Many labs use Roche Immunoassay to detect the presence of Thyroglobulin Antibodies, and this method has a different range than the method used by Quest/LabCorp. Quest and LabCorp use the Beckman Coulter immunometric assay to determine the presence of antibodies to Thyroglobulin. According to this methodology, any result >1.0 indicates the presence of antibodies, so further investigation is warranted.
Unfortunately, we cannot convert a result from the Roche Assay to the result from Quest or Labcorp because we would be comparing apples to oranges. However, we make accommodations for the following labs and use their ranges for Thyroglobulin Abs in our reporting when you select them from the drop-down menu:
- Lab Tech: 0 - 115 IU/ml
- Vibrant: 0 - 115 IU/ml
- LifeLabs: 0 - 40 IU/ml
If your lab has ranges that are different than those above or your lab is not included in the dropdown then we recommend not entering a value for the Thyroglobulin Antibody into the software but notating the result with ranges, etc., in the "Practitioners Notes" section. This will allow you to draw your client's attention to this while allowing the software to work on the other thyroid biomarkers that you can enter into the program.
The next question that comes up is about the sensitivity of one method over another. The Roche testing methodology used by many labs is as valid, sensitive, and accurate as the one used by Quest or LabCorp. They are just using a different "normal" value to express the levels of antibodies detected. Unfortunately, they are not interchangeable with the ones used by Quest or LabCorp.