Thyroid

  1. What are the new conversion factors for TG and TPO on ImmunoCAP?

    The conversion factors are fixed in the software and are different for ImmunoCAP 100 vs ImmunoCAP 250:

     - TPO     16.7
     - TG       122

    ImmunoCAP 100:
     - TPO      18
     - TG       140

     For EliA there is no conversion factor, the factor is different from lot to lot and is implemented in the barcode.

     

    Detection limits

    With these conversion factors you can calculate the detection limits by multiplying with 2 for the lower detection limit and with 200 for the upper detection limit.  

    Assay

    conversion factor

    detection limits

    TPO on ImmunoCAP 250

    16.7

    33.4 - 3340 IU/ml

    TG on ImmunoCAP 250

    122

    244 - 24400 IU/ml

    TPO on ImmunoCAP 100

    18

    36 - 3600 IU/ml

    TG on ImmunoCAP 100

    140

    280 - 28000 IU/ml

     

  2. Why is UniCAP TG not included in NEQAS?

    TG antibodies are not included any more because NEQAS has the opinion that measuring TPO alone is sufficient and TG doesn't add any further information. Therefore TG is almost not measured any more in the UK.

    This is the general international opinion of most of the opinion leaders. However, there are still some hints in the literature, that TG Abs is a valid marker.

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.