Sensitivity of three thyrotropin receptor antibody assays in thyroid-associated orbitopathy

Abstract

Background: Thyrotropin receptor autoantibodies (TSH-R-Ab) are indispensable biomarkers in the laboratory assessment of thyroid-associated orbitopathy (TAO). Clinical sensitivity of three different assays for TSH-R-Ab determination was evaluated in patients with TAO.
 Methods: 87 consecutive TAO patients were enrolled and their serum samples analyzed in parallel with three assays. An ECLIA competitive binding and a chemiluminescent bridge immunoassay were used to measure total and binding TSH-R-Ab concentration, while their functional activity was determined using a stimulatory TSH-R-Ab (TSAb) cell-based bioassay.
 Results: Compared to the two binding assays (ECLIA p<0.001, bridge p=0.003), the TSAb bioassay was more sensitive pertaining to the positive detection of TSH-R-Ab in TAO patients. No difference (p=0.057) was noted between the ECLIA and bridge assays regarding sensitivity rate. All patients with active and/or moderate-to-severe TAO tested positive in the TSAb bioassay (100% and 100%, respectively), while the positivity rates for bridge and ECLIA binding assays were 89.7% and 82.1% for active TAO, and 90.2% and 86.3% for severe TAO, respectively. Negative predictive values of the bioassay, bridge, and ECLIA assays were 100%, 75%, and 71%, respectively for active TAO, and 100%, 86%, and 71%, respectively for moderate-to-severe TAO. The superiority of the bioassay was most prominent in euthyroid (ET) TAO. Positivity rates of the TSAb bioassay, bridge and ECLIA binding assays were 89.6%, 75%, and 64.6%, respectively for inactive TAO; 86.1%, 69.4%, and 52.8%, respectively for mild TAO; 87.5%, 62.5%, and 12.5%, respectively for euthyroid TAO. The bridge assay correlated better with the ECLIA binding assay (ρ=0.893, p<0.001), compared to the bioassay (ρ=0.669, p<0.001).
 Conclusions: In patients with TAO of various activity and severity, the TSAb bioassay demonstrates a superior clinical performance compared to both ECLIA and bridge binding assays.

The changing landscape of thyroid eye disease: current clinical advances and future outlook

“…The role of the TSH-Receptor antibodies, is unclear although they likely play a crucial role in the pathogenesis of TED. A variety of antibodies exist including stimulating, blocking and neutralising and how these antibodies interact with the TSH-Receptor at different type points on Rundle’s curve is not fully understood [ 119 , 120 ]. The different forms of antibodies, may predominate and impact certain ethnic populations to various degrees [ 121 , 122 ].…”

Evaluation of some biochemical markers in alopecia areata

“…For ESR estimation, the Westergren's method was used [13] . Measuring TSH was performed using Cobas ECLIAs (Roche Diagnostics GmbH, Mannheim, Germany) [14] .…”

Molecular Biomarkers in Thyroid Eye Disease: A Literature Review

“…The superior sensitivity of TSI over TBII has later been confirmed in subcategories of TED, including euthyroid patients and mild cases of TED. [27][28][29] There is evidence supporting a correlation between TSI levels and CAS, and some studies indicated that TSI levels also correlate with the severity of TED. [30][31][32] Furthermore, TSI has been evaluated for predicting active TED with a sensitivity of 77.4%, specificity of 81.3%, and area under the curve (AUC) of 84.7%.…”