Evaluation of a new rapid and fully automated electrochemiluminescence immunoassay for thyrotropin receptor autoantibodies.
BACKGROUND
Hyperthyroidism in Graves' disease is caused by autoantibodies to the TSH receptor (TSHR), and measurement of the TSHR autoantibody (TRAb) yields important information to diagnose and decide on the course of treatment of Graves' disease. We evaluated basic and clinical performance of a new, rapid, and fully automated electrochemiluminescence immunoassay Elecsys Anti-TSHR (Elecsys TRAb) for measuring serum TRAb.


METHODS
For evaluation of basic performance of the assay, we carried out intra- and interassay precision studies using five serum pools and three serum pools, respectively, and the assay was compared with four commercial TRAb assays. Clinical performance of the assay was evaluated with sera from 298 patients with untreated Graves' disease, 220 patients with destructive (painless and subacute) thyroiditis, and 332 healthy volunteers. The optimal cutoff point, which was calculated by receiver operating characteristic (ROC) analysis with the above subjects, was then used to classify an independent sample set of 80 patients with untreated Graves' disease, and 152 patients with destructive thyroiditis.


RESULTS
Intraassay coefficient of variation (CV) was 4.24% at 1.85 IU/L and interassay CV was 10.1% at 1.46 IU/L. All the correlation coefficient values calculated against four commercial assays were larger than 0.85. ROC analysis resulted in a specificity of 99.1% with a sensitivity of 97.0% at a decision limit of 1.86 IU/L from comparison with untreated Graves' disease and destructive thyroiditis. The cutoff point yielded a sensitivity of 87.5% and specificity of 96.7% with the independent sample set.


CONCLUSIONS
In spite of the short measuring time of only 27 minutes, the assay showed the same or better results with the existing commercial products. The short measuring time would contribute to speedy, preconsultation diagnosis of thyroid disease, especially of Graves' disease.
Yoshimura Noh
Jaeduk
J
Internal Medicine, Ito Hospital, Tokyo, Japan. h-yoshimura@ito-hospital.jp
Miyazaki
Naoko
N
Ito
Koichi
K
Takeda
Kyoko
K
Hiramatsu
Sonoe
S
Morita
Shinji
S
Miyauchi
Akira
A
Murakami
Tsukasa
T
Inomata
Keiko
K
Noguchi
Shiro
S
Satoh
Tomoaki
T
Amino
Nobuyuki
N
D000328:Adult; D000368:Aged; D001331:Automation; D005260:Female; D006111:Graves Disease / Q000175:diagnosis / Q000276:immunology; D006801:Humans; D007118:Immunoassay / Q000379:methods* / Q000706:statistics & numerical data; D018828:Immunoglobulins, Thyroid-Stimulating / Q000097:blood*; D008163:Luminescent Measurements / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013968:Thyroiditis, Subacute / Q000175:diagnosis / Q000276:immunology; D055815:Young Adult
D018828:Immunoglobulins, Thyroid-Stimulating; C094372:thyrotropin-binding inhibitory immunoglobulin