Is there one successful antithyroid regimen for Graves' disease?

Practical treatment with minimum maintenance dose of anti-thyroid drugs for prediction of remission in Graves' disease

Although many researchers have reported clinical and laboratory parameters for prediction of remission in Graves' disease during or after anti-thyroid drug therapy, there is no reliable one to assure the complete remission. We prospectively examined a practical therapy with minimum maintenance dose of anti-thyroid drugs for prediction of remission in Graves' disease. Fifty-seven patients with Graves' disease were treated with anti-thyroid drugs at the initial dose of 30 mg/day of methimazole (MMI) or 300 mg/day of propylthiouracil (PTU). Then, doses were gradually decreased, and finally discontinued when the patients were able to maintain euthyroid (normal FT4 and TSH) for at least 6 months with the minimum maintenance dose (MMI 5 mg every other day or PTU 50 mg every other day). After discontinuation of drugs, FT4, FT3, TSH and TSH-binding inhibitory immunoglobulin (TBII) were measured every one to two months for the first 6 months and every 3-4 months for the next 18 months to confirm continuous remission. After 2 years of drug cessation, 46 (81%) of 57 patients were in remission and the other 11 patients had relapsed into thyrotoxicosis. At the time of drug discontinuation, the serum concentration of FT4, FT3 and TSH, titers of anti-thyroglobulin antibodies and anti-thyroid microsomal antibodies, goiter size were not different between the remission and relapse groups. At the time of drug cessation, the activities of TBII and thyroid-stimulating antibodies (TSAb) overlapped between the two groups, although they were significantly lower in the remission group than in the relapse group (p<0.01). Forty percent (4/10) of TBII positive patients and 71% (23/32) of TSAb positive patients continued to be in remission. On the other hand, thyrotoxicosis relapsed in 5 (11%) of 47 TBII negative and 2 (8%) of 25 TSAb negative patients. These data indicate that minimum maintenance therapy to keep euthyroid (normal FT4 and TSH) for 6 months is a practical measure for 81% prediction of remission in Graves' disease. The measurement of TBII or TSAb gave little additional information for predicting remission.

Outcome of treatment of hyperthyroidism

This is a retrospective study designed to evaluate the initial response to carbimazole in patients with Graves' disease (GD), possible determinants of that response, the frequency of occurrence of adverse effects during treatment with carbimazole and the frequency of transient and permanent hypothyroidism after treatment with 131I in patients with GD and multinodular goiter (MNG). Data were collected from patients who first presented with GD or MNG at the Department of Endocrinology of the Royal Infirmary of Edinburgh between 1 January 1993 and 31 August 1996. Patients were divided into three groups: patients with GD treated with a daily dose of 40 mg carbimazole, patients with GD treated with a single dose of 400 MBq 1311, and patients with MNG treated with the same dose of 131I. Of the patients younger than 30 years, 50% remained biochemically hyperthyroid after 4-6 weeks of treatment with carbimazole, compared to 14% of patients over 30. Other determinants of the response to carbimazole expressed as the fall in thyroid hormone levels after 4-6 weeks were: pretreatment levels of FT4, T3, TRAb and the 4 h 131I uptake, patients with the higher levels responding significantly better to carbimazole. Adverse effects were reported in 11.5% of patients. Of the patients with GD treated with 1311, 62.6% became hypothyroid, transient hypothyroidism occurred in only 2.4% of these cases. The main predictors of development of hypothyroidism were positive titres of antithyroid peroxidase antibodies (AbTPO) and antithyroglobulin antibodies (AbTg), with positive predictive values of 79.5 and 91.6 respectively. None of the patients with MNG became hypothyroid after treatment with 131I, a response significantly different from patients with GD. In conclusion, GD younger patients might benefit from higher initial doses of carbimazole. In patients with positive titres of AbTPO and AbTg, lower doses of 1311 might prevent hypothyroidism. Transient hypothyroidism was underestimated in this study. No permanent thyroxin replacement therapy should be started within the first six months after 131I treatment.

Thyrotropin receptor antibodies in black South African patients with Graves' disease and their response to medical therapy

Graves' disease is increasing in incidence amongst urban black South Africans. The pathogenic role of thyrotropin receptor antibodies (TRAb), crucial in other populations, has not been formally evaluated in African communities. We therefore prospectively investigated the prevalence of TRAb in 30 consecutive urban black South African patients with classical Graves' disease at the onset of their illness. This was compared with the frequency of thyroid microsomal and thyroglobulin antibodies in the same patients. Ten patients with euthyroid goitres unrelated to Graves' disease and 10 healthy controls were also studied. Twenty of the hyperthyroid patients were retested 4-6 months after starting carbimazole therapy and ten of them again after 1 year. Initially 83% of patients were positive for TRAb as against 54% for thyroid microsomal and 1 7% for thyroglobulin antibodies. After 4-6 months of treatment, 65% of patients still had elevated (>15% inhibition of binding) TRAb titres, while at 1 year this had dropped to 40% (4 out of 10 patients). All positive patients had relapsed biochemically, while TRAb negative patients were all in remission. We conclude that TRAb are a sensitive and specific marker of Graves' disease in black South Africans and closely parallels the response to medical therapy at 1 year. However, their predictive value for delayed relapse requires the study of a larger cohort of patients over a longer time-frame.

Elevated CD69 expression on naive peripheral blood T-cells in hyperthyroid Graves' disease and autoimmune thyroiditis: discordant effect of methimazole on HLA-DR and CD69

This study investigated T-cell activation markers HLA-DR and CD69 in both naive (CD45RA+) and memory (CD45RA-) CD4+ as well as CD8+ T cells in peripheral blood of patients with autoimmune thyroiditis (AT, N = 28) or hyperthyroid untreated Graves' disease (GDH, N = 34) using three-color flow cytometry. It was demonstrated that patients with AT, but not those with GDH, expressed increased amounts of HLA-DR antigen compared to healthy subjects (HS, N = 26) on total CD4+ (AT: 14.1%; GDH: 11.3%; HS: 10.9%) and CD8+ cells (AT: 31.9%; GDH: 23.5%; HS: 19.4%) as well as on CD45RA- CD4+ cells (AT: 11.2%; GDH: 7.7%; HS: 7.9%). In GDH (+71%) and AT (+91%) only the proportion of HLA-DR+ CD45RA+ CD8+ cells was increased vs HS. Furthermore, euthyroid GD patients on methimazole (GDE, N = 22) displayed greater HLA-DR+ expression on total and CD45RA- cells within both CD4+ (+37 and 40%, respectively) and CD8+ cells (+47 and 93%, respectively) than GDH. In addition, total and CD45RA+ CD4+ and CD8+ cells were increased vs HS. In contrast, proportions of CD69 positive T cells were increased in AT and GDH on total CD4+ (+97 and 74%, respectively) and CD8+ (+95 and 68%, respectively) cells and all subsets thereof (except for CD45RA- cells in GDH), but normalized upon thyrostatic treatment. We conclude that patients with autoimmune thyroid disease harbor an almost twofold greater proportion vs HS of (a) HLA-DR+ CD45RA+ CD8+ T cells, and of (b) CD69 on total CD4+ and CD8+ cells, and an even more marked elevation on their CD45RA+ subset in AT and untreated GD. In addition, (c) thyrostatic treatment by methimazole in GD is accompanied by a further increase in circulating HLA-DR+ CD4+ and CD8+ cells and their CD45RA- subsets, but decreased CD69 expression. These data suggest association of HLA-DR expression with ongoing autoimmunity, while increased CD69 expression relates in part also to elevated thyroid hormone concentration in GDH.

TSH suppression combined with carbimazole for Graves' disease: effect on remission and relapse rates

OBJECTIVE

We studied the influence of TSH suppressive therapy combined with carbimazole (CBZ) on treatment outcome in Graves' disease.

DESIGN

Open non-randomized prospective study.

SETTING

University Hospital of Montpellier, France.

SUBJECTS

Sixty-six consecutive patients without prior treatment were included. All the patients were treated initially with 30 mg of CBZ. After 1 month of treatment, one group continued CBZ alone (n = 23), another group received a combination of CBZ plus T3 (n = 19) and a third group received CBZ and 3,5,3'-triiodothyroacetic acid (Triac, n = 24). Therapy was stopped when remission was obtained based on clinical euthyroidism, normalization of FT4 and of early radioiodine uptake. Nine patients with medical treatment failure or major side effects requiring to stop antithyroid drugs underwent surgery or radioiodine therapy. Nine patients were lost to follow-up. The remaining 48 patients were available for analysis of both remission and relapse.

RESULTS

The median duration of therapy was 18 months (range, 4-41 months). Based on clinical examination, goitre size at 4 months decreased more in the CBZ + T3 and CBZ + Triac groups than in the CBZ group (P = 0.02). The overall remission rate tended to be higher in the groups treated with CBZ + T3 and CBZ + Triac than in the group treated with CBZ alone, but the difference did not reach statistical significance (P = 0.17). No difference in the relapse rate was observed between the three groups.

CONCLUSION

TSH suppression combined with CBZ has little or no effect on remission and relapse rates in Graves' disease patients.