Abstract
Measurements of TSH receptor autoantibodies (TRAb) using assays based on the human
monoclonal TSH receptor autoantibody M22 or bovine TSH have been compared in 136 adult
patients. They suffered from Graves’ disease (GD, n=62), Hashimoto's thyroiditis (HT,
n=26), or non-autoimmune hyperthyroidism (NAH, n=48) and were selected on the basis
of undetectable, borderline or low TRAb levels (0.6–3 IU/l) as measured by TSH based
TRAb assay (Dynotest® TRAKhuman from BRAHMS). The time interval between initial diagnosis of GD and TRAb
determination was high and ranged from 1 month to 3.5 years (median: 2.3 years). Using
the kit manufacturer's cutoff values, 53/62 (85.5%) of the selected group of GD patients
were TRAb positive (>0.4 IU/l) by M22 based TRAb ELISA (Medizym® TRAb clone, Medipan) and 45/62 (72.6%) were TRAb positive (>1.5 IU/l) by TSH based
TRAb assay. In the HT group, 9/26 (34.6%) sera were positive in the M22 based ELISA
and all but one of these 9 were positive or borderline in the TSH based assay. ROC
plot analysis of the GD group using the NAH group as reference showed that at 95%
specificity, the bovine TSH based TRAb assay had a sensitivity of 62.9% (cutoff for
positivity=1.64 IU/l) and the M22 based TRAb ELISA a sensitivity of 90.3% (cutoff
for positivity=0.32 IU/l). Overall therefore, the M22 based Medizym® TRAb clone assay is more sensitive than the bovine TSH based Dynotest® TRAK human assay.
Key words
thyroid - autoantibodies - TSH receptor - Graves’ disease - Hashimotos’ disease
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Correspondence
Priv-Doz. Dr. med. K. Zöphel
Department of Nuclear Medicine
Carl Gustav Carus Medical School
University of Technology
Dresden Fetscherstraße 74
01307 Dresden
Germany
Phone: +49/351/458 138 79
Fax: +49/351/458 53 47
Email: klaus.zoephel@uniklinikum-dresden.de
