T. Kashiwai et al., SIGNIFICANCE OF THYROID-STIMULATING ANTIBODY AND LONG-TERM FOLLOW-UP IN PATIENTS WITH EUTHYROID GRAVES-DISEASE, Endocrine journal, 42(3), 1995, pp. 405-412
We examined 13 patients with euthyroid Graves' disease suspected ophth
almologically, by comparing them with 20 patients with untreated Grave
s' disease and by following them up for 5 to 10 years. They had Graves
' ophthalmopathy (NOSPECS class II similar to IV) without other ocular
diseases, normal levels of serum thyroid hormones, and no previous hi
story of Graves' disease. Proptosis in euthyroid Graves' disease was n
ot significantly different from that in untreated Graves' disease. In
3 patients with euthyroid Graves' disease, TSH was suppressed. There w
as either no TSH response to TRH or it was low in 7 of 12 patients exa
mined. The result of a TS-suppression test was abnormal in 8 of II pat
ients examined. Titers of serum TGHA, MCHA, TSH-binding inhibitory imm
unoglobulin (TBII), and thyroid stimulating antibody (TSAb) were signi
ficantly lower in patients with euthyroid Graves' disease compared tha
n in patients with untreated Graves' disease. TSAb, however, was posit
ive in 12 of 13 (92%) patients. In spite of positive TSAb, 9 of 13 pat
ients with euthyroid Graves' disease had normal radioactive iodine upt
ake (RAIU). During the observation period, various abnormalities in th
yroid function developed: persistent hyperthyroidism in 5 patients (38
%), transient thyrotoxicosis in 2 (15%) and transient hypothyroidism i
n 1 (8%). We conclude that euthyroid Graves' disease is a subtype of G
raves' disease that minimally develops thyrotoxicosis in spite of the
existence of TSAb due to some mechanism inhibiting thyroid growth or s
timulation, and that the measurement of TSAb provides a useful marker
for the diagnosis of this disease.