Clinical characteristics of G raves' orbitopathy in patients showing discrepancy between levels from TBII assays and TSI bioassay

Objective To investigate clinical characteristics of patients with G raves' orbitopathy ( GO ) who showed discrepancies between levels of thyroid‐stimulating immunoglobulin ( TSI ) and thyrotropin‐binding inhibitory immunoglobulin ( TBII ). Design Comparative case series. Patients A total of 317 patients with GO in whom Mc4‐ TSI and M22‐ TRA b (third‐generation TBII ) were measured simultaneously. Patients were divided into four groups according to TRA b levels as followings: G roup 1, TBII and TSI  < median value; G roup 2, TBII  ≥ median, TSI  < median; G roup 3, TBII  < median, TSI  ≥ median; G roup 4, both TBII and TSI  ≥ median. Measurement Endocrine and ophthalmic clinical manifestations in each group. Results The median value of M 22‐ TRA b was 6·11 IU /l and that of M c4‐ TSI was 415·1 ( SRR %). One hundred seventeen patients were classified as G roup 1, 41 patients as G roup 2, 41 patients as group 3 and 118 patients as group 4. Mean CAS was significantly higher in G roups 3 (2·2) and 4 (2·2) than in G roups 1 (1·6) and 2 (1·4; P  =   0·001, anova ). Mean modified NOSPECS scores were significantly higher ( P  <   0·001, anova ) in G roups 3 (4·1) and 4 (4·1) than in G roups 1 (3·1) and 2 (2·3). The proportion of patients with hyperthyroidism was larger in Group 2 (85·4% [35/41 patients]) than in G roup 3 (48·8% [20/41 patients]; P  =   0·002). Conclusions GO is more active and severe in patients with predominant M c4‐ TSI than in patients with predominant M 22‐ TRA b. Patients with hyperthyroidism were more likely to be included with patients with predominant M 22‐ TRA b than with predominant M c4‐ TSI .