Changes in Thyroid Function in Euthyroid Subjects with a Family History of Graves' Disease: A Foliow-Up Study of 69 Patients*

Abstract

TRH tests were performed in 206 clinically and biochemically euthyroid relatives of patients with Graves' disease. In 117 of the 206, T3 suppression tests were performed. Results revealed that 56 of the 206 (27.1%) showed abnormal responses to TRH. Twenty-nine of these (14.1%) revealed absent or decreased responses, and 27 (13.1%) revealed augmented responses to TRH. Eight of the 117 (6.8%) were T3 nonsuppressible. These eight subjects consisted of 4 subjects out of 17 hyperesponders and 4 subjects out of 90 normal responders. The majority of suppressible subjects (86 among 109) demonstrated normal responses to TRH. Sixty-nine of the 206 subjects were followed for 6 months to 5 yr to observe changes in their thyroid functions. Among all 69 subjects 3 became clinically thyrotoxic 12, 12, and 18 months after their initial visit, respectively, and 2 became clinically hypothyroid 2 yr after their initial visit. Since 69 subjects were clinically and biochemically euthyroid and had no goiter or exophthalmos at their initial visit, the incidence of thyrotoxicosis or hypothyroidism in these subjects could be considered to be remarkably high. It is of interest that the 3 thyrotoxic patients were TRH hyporesponders at their first visit. One patient was T3 suppressible; T3 suppression tests were not performed in the other 2 patients at their initial visit. There was no abnormality in the first TRH test in 2 relatives who became hypothyroid. It is suggested that 1) among euthyroid relatives with a family history of Graves' disease, there are many with abnormalities in TRH responsiveness and T3 suppressibility, 2) nonsuppressible subjects are more likely to be TRH hyporesponders and vice versa, 3) hyperthyroidism or hypothyroidism occurs frequently in euthyroid relatives with a family history of Graves' disease, and 4) thyrotoxicosis occurs frequently in TRH-hyporesponders, and hypothyroidism occurs in the others.

Immune Mechanisms In Graves' Disease

“…It is known that relatives of Graves' patients may have immunologic abnormalities: about 25% may have positive LATS levels; some patients may have abnormal thyroid function tests, TRH stimulation tests, and/or T 3 suppression tests (283)(284)(285)(286)(287)(288)(289)(290). Wall et al in 1969 (284), reported the prevalence of TSH receptor antibodies in relatives of Graves' disease patients was 23%.…”

Hypothalamic-Pituitary-Thyroidal Dysfunctions in Anorexia nervosa

“…TSH responsiveness was defined as being positive when the basal scrum TSH concentration was < 2.0 pU/ml and the peak value was > 6.2 pU/ml or if the basal value was > 2.0 pU/ml and ATSH (peak TSH-basal TSH) was > 5 pU/ml. Responses below those limits were considered to represent a hyporesponse, hyperresponsiveness to TRH was defined as a peak value of TSH > 35 pU/ml and a delayed response was defined as a peak value of TSH occurring later than 60 min after TRH injection [16,17]. …”

A study of thyroid function after subtotal thyroidectomy for Graves' disease: particularly on TRH tests, T3 suppression tests and antithyroid antibodies in euthyroid patients

“…T3 suppression tests and TRH tests T3 suppression tests were performed by measuring the 24 h thyroid 131I uptake after administration of 75 µg T3 daily for 8 days. T3 suppressibility was defined as sup¬ pression of the 24 h thyroid 131I uptake after T3 admini¬ stration to more than 50% of the initial uptake before T3 administration (Tamai et al 1980). TRH tests were performed by injecting iv 500 µg synthetic TRH (Tanabe Seiyaku), and blood samples for TSH concentrations were obtained 0, 30, 60 and 90 min after TRH injection.…”