IMMUNOLOGICAL FINDINGS AND THYROID-FUNCTION OF UNTREATED GRAVES-DISEASE PATIENTS WITH UNDETECTABLE TSH-BINDING INHIBITOR IMMUNOGLOBULIN

OBJECTIVE TSH-binding inhibitory immunoglobulin (TBII) is undetectable in about 10% of untreated Graves' disease patients, but the clinical characteristics and immunological significance of this finding are unk nown. In this study we evaluated the clinical characteristics of TBII negative Graves' disease. PATIENTS We examined TBII in 1048 untreated patients at Kuma hospital from 1986 to 1990 and found 69 TBII undetect able patients (12 men and 57 women, mean age +/- SEM 35 +/- 2 years, g roup A). MEASUREMENTS We compared the clinical characteristics and imm unological findings of group A with 57 untreated Tell detectable Grave s' patients who were selected randomly (11 men and 46 women, mean age +/- SEM 40 +/- 2 years, group B). T4, TSH, FT4, FT3, I-123 thyroid upt ake, TBII, thyroid stimulating antibodies (TSAb) and the volume of the thyroid using ultrasonography were measured at the first visit. RESUL TS Serum T4, FT4 and FT3 levels in group A were significantly Tower th an those in group B (P < 0.001). The values of TSAb in group A were si gnificantly lower than those in group B (593 +/- 67 (mean +/- SE) vs 2 143 +/- 280%, respectively, P < 0.001). The I-123 thyroid uptake in gr oup A was significantly lower than that in group B (53.1 +/- 1.1 vs 61 .4 +/- 1.4%, respectively, P < 0.01). The thyroid volume in group A wa s significantly smaller than that in group B (39.1 +/- 3.0 vs 51.3 +/- 3.3 mi, respectively, P < 0.01). TSAb was undetectable in about 10% ( 6) of the TBII negative untreated Graves' patients at their first visi t. CONCLUSION In the present study, untreated TBII negative patients w ith Graves' disease were characterized by mild elevation of thyroid ho rmones, mildly elevated I-123 uptake, weak TSAb activities and small g oitres. The finding of both TBII and TSAb negative titres in untreated Graves' disease patients was also confirmed.