Outcome of patients with Graves' disease after long-term medical treatment guided by triiodothyronine (T3) suppression test

Drug discontinuation after treatment with minimum maintenance dose of an antithyroid drug in Graves' disease: a retrospective study on effects of treatment duration with minimum maintenance dose on lasting remission

According to the guideline issued by the Japan Thyroid Association in 2006 for treatment of Graves' disease, discontinuing antithyroid drug (ATD) therapy is recommended when serum free thyroxine (FT4) and thyroid stimulating hormone (TSH) concentrations have been maintained within the reference range for a certain period after treatment with one ATD tablet every other day (minimum maintenance dose therapy, MMDT). In this retrospective study, the relationship between MMDT duration and remission rate was investigated. The participants were 107 consecutive patients with Graves' disease whose ATD therapy was stopped according to the guideline. Serum FT4, TSH, and TSH receptor antibody (TRAb) levels were measured when ATD was discontinued and every 3 months thereafter. The percentage of patients in remission was 86.9% at 6 months, 73.8% at 1 year, and 68.2% at 2 years after ATD discontinuation. The remission rate increased with MMDT duration, being significantly higher in patients with MMDT durations of 19 months or more than those with MMDT durations of 6 months or less. In patients with MMDT durations of 6 months or less, the remission rate was significantly lower in TRAb-positive patients than in TRAb-negative patients at the time of withdrawal of ATD; however, this was not observed in patients with MMDT durations of 7 months or more. These findings suggest that in patients who discontinue ATD after a certain MMDT duration, the remission rate increases as the MMDT duration increases, and ATD should not be discontinued in TRAb-positive patients with MMDT durations of 6 months or less.

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.

Reduction of the risk of relapse after withdrawal of medical therapy for Graves' disease

It has been a continuing challenge to try and identify those patients with hyperthyroid Graves' disease likely to remain in remission after an antithyroid drug course or to manage the medical treatment so as to increase the chance of remission. On average, the overall relapse rate is approximately 50% and any significant reduction of this figure would be of practical as well as theoretical value. The numerous controlled prospective studies performed in many parts of the world, with varying iodine intakes, have all confirmed that the main initial features related to the subsequent risk of relapse are: young age, male gender, goiter larger than 40 mL, hypoechogenic and hypervascular gland, high level of anti-thyrotropin receptor antibody (TRAb), detected either with radioreceptor assay (TBII: >40 U/L) or the biologic stimulation assay (thyroid-stimulating antibodies [TSAb]; >300%), severity of hyperthyroidism, and possibly the presence of ophthalmopathy. Alone, each of these has a low predictive value, but together they allow evaluation of the risk of relapse, thus helping treatment choice. As to the modalities of antithyroid drug treatment, dose of the drug or addition of levothyroxine does not affect posttreatment outcome. In contrast, significantly fewer relapses occur for drug courses longer than at least 1 year. Persistence of high levels of TRAb after medical treatment is strongly predictive of relapse but this is of limited value because in most patients, TRAb levels are low or even undetectable at the end of treatment, which does not indicate for further outcome. Smoking is a significant independent risk factor for relapse. In conclusion, reduction of the risk of relapse in patients with medically treated hyperthyroid Graves' disease relies on clinical competence and appropriate management taking into account an array of factors none of which alone has definite predictive value.

Antithyroid drugs and Graves' disease--prospective randomized assessment of long-term treatment

OBJECTIVE

Although antithyroid drugs (ATD) are widely used in the treatment of Graves' disease, management protocols, especially treatment duration, remain a subject of debate. The rate of relapse after short-term regimens of less than 6 months with ATD at decreasing doses is higher than after longer treatments from 12 to 24 months. As no prospective study has provided data on even longer protocols exceeding 2 years, we conducted a prospective trial to determine potential benefits of a 42-month treatment compared with an 18-month treatment.

DESIGN, PATIENTS AND MEASUREMENTS

The aim of this prospective randomized trial was to compare relapse rates achieved two years after treatment withdrawal in patients who received carbimazole at decreasing doses for 18 months (n = 62) vs 42 months (n = 72). In addition to clinical relapse rate, the percentage of patients who normalized antithyroperoxidase (TPO) antibody and anti-TSH receptor stimulating antibody (TSAb) levels and early iodine uptake at the end of treatment were assessed as outcome criteria.

RESULTS

The relapse rate two years after discontinuation of treatment did not differ significantly in patients treated for 18 months from those treated for 42 months (36% vs 29%, NS). At the end of treatment, there was no significant difference between the two groups in the percentage of anti-TPO positive patients (53% vs 46%, NS) or early iodine uptake (27% vs 21%, NS). Although the percentage of patients with TSAb was significantly lower in the 42-month treatment group (18% vs 42%, P = 0.004) at treatment withdrawal, the percentage of TSAb-positive patients did not significantly decrease between 18 and 42 months in this group (27% vs 18%, NS).

CONCLUSION

Treatment duration greater than 18 months did not improve remission rate determined 2 years after treatment withdrawal or immunological variables or early iodine uptake measured at the time of discontinuation of treatment. These findings would indicate that, when a defined duration treatment is planned, prolonging treatment beyond 18 months does not provide any additional benefit.

Prognostic Value of Suppressed Thyrotropin Level and Positive Thyrotropin-Receptor Antibody Activity in Graves’ Disease with Long-Lasting Clinical Remission

OBJECTIVE

To determine the prognostic value of suppressed thyrotropin (TSH) level and positive TSH-receptor antibodies (TSH-R Ab) in patients with Graves' disease who have long-lasting clinical remission.

METHODS

We retrospectively studied patients with Graves' disease who underwent follow-up for a mean of 55 months after the withdrawal of antithyroid drug treatment. Study patients were 84 consecutive subjects in clinical remission, with normal serum free thyroxine (FT(4)) and free triiodothyronine (FT(3)) levels, regardless of serum TSH levels, a mean of 35 months (range, 6 to 135) after discontinuation of carbimazole therapy. Eighty-seven euthyroid subjects were used as control study participants. All subjects had serum determinations of FT(4) and FT(3) (radioimmunoassay), TSH (highly sensitive immunoradiometric method), TSH-R Ab (radioreceptor assay), and microsomal antibodies (M Ab, passive hemagglutination method).

RESULTS

In the study patients, serum TSH was suppressed (</=0.10 mU/L) in 13 cases (15%), TSH-R Ab were positive (>/=15%) in 11 cases (13%), and M Ab were positive (>/=1:100) in 54 cases (64%). Simultaneous suppressed TSH and positive TSH-R Ab levels were present in six patients. During the follow-up, 11 patients had a relapse, demonstrated by above-normal values for serum FT(4) and FT(3) in association with clinical symptoms of hyperthyroidism. Five of them had a previously suppressed TSH level, three had a positive TSH-R Ab level, and six had a positive M Ab titer. Relapse was significantly more likely in patients with a previously suppressed TSH level (P<0.02) but not in patients with a previously positive TSH-R Ab level or positive M Ab titer.

CONCLUSION

Patients with Graves' disease and long-lasting clinical remission after discontinuation of carbimazole therapy may have a suppressed TSH level, a positive TSH-R Ab level, or a positive M Ab titer (or some combination of these findings). Although positive TSH-R Ab and M Ab have no significant prognostic value, a suppressed TSH level is indicative of subclinical hyperthyroidism and higher risk of relapse.

Simple and reliable method for predicting the remission of Graves' disease: revised triiodothyronine-suppression test, indexed by serum thyroxine

To find a simple and reliable method for predicting the long-term remission of Graves' disease, we studied the outcome of 182 methimazole-treated patients with Graves' disease, whose thyroidal RAIU became < 12% after T3 administration. The patients were treated with methimazole over 2 years. T3 suppression test was done 6 months after the disappearance of TSH-receptor antibody (TRAb); the patients took T3 for 14 days, and on the 14th day, blood was obtained for serum T3, T4, and TSH determination, and RAIU was measured. These 182 patients were followed for 5 years after methimazole withdrawal. We divided the 182 methimazole-treated patients, whose thyroidal RAIU became < 12% after T3 administration, into two groups based on the outcome after the discontinuation of methimazole; 40 patients (22%) had an overt recurrence (group A) and the other 142 (78%) did not (group B). The degree of serum T4 suppressibility by T3 was less in group A than in group B. In group A, the number of the patients with a serum T4 < 60% of the pre-T3 levels is less than that with a serum T4 > or = 60%, but, in group B the former is more than the latter. The serum T4 < 60% of the pre-T3 level was significantly associated with the remission.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term follow-up studies on iodine-131 treatment of hyperthyroid Graves' disease based on the measurement of thyroid volume by ultrasonography

In the present series of studies, the long-term (four year) effect of 80 Gy of 131I treatment was evaluated in patients with hyperthyroid Graves' disease whose thyroid volumes have been accurately estimated with a high resolution ultrasound scanner. One year after 131I treatment, 23.1% (3 out of 13 patients) remained hyperthyroid, 69.2% (9 out of 13) became euthyroid, and 7.7% (1 out of 13) were in a hypothyroid state. Since three patients in a hyperthyroid state one year after treatment were subsequently treated with either antithyroid drugs or additional 131I treatment, the remaining ten patients (9 euthyroid and 1 hypothyroid patients) have been followed up for three more years. Two patients developed a hypothyroid state three years after treatment and one patient four years after treatment. Overall, 60% (6 out of 10 patients) were in a euthyroid state and 40% (4 out of 10) in a hypothyroid state, four years after 80 Gy 131I treatment. There was no significant difference between eu- and hypothyroid groups in the sex ratio, age, radiation dose, therapeutic dose, thyroid gland volume, 24-hr 131I uptake, the effective half-life of 131I in the thyroid or the duration of hyperthyroidism. In our preliminary studies, the incidence of late hypothyroidism in our 131I treatment is similar to those previously reported. These suggest that uncertain factor(s), such as inhomogeneity of iodine distribution in the thyroid, unequal sensitivity of the thyroid cells to the radiation, and/or persistent destructive effects of the autoimmune process may influence the long-term effect of 131I treatment of Graves' disease.

Serum thyroid-stimulating antibody, thyroglobulin levels, and thyroid suppressibility measurement as predictors of the outcome of combined methimazole and triiodothyronine therapy in Graves' disease

The value of the criteria used to anticipate the outcome of treatment of Graves' hyperthyroid patients with methimazole (MMI) remains controversial. We have reported that high MMI doses combined with T3 administration was correlated with higher remission rates. In this study, we used the lowest MMI dose able to control the hyperthyroidism, keeping the free T4 index (FT4I) values below the normal range throughout treatment, and compared the results with patients treated with a high MMI regimen. Both groups received T3. We also evaluated the usefulness of goiter size, serum thyroid-stimulating antibody (TSAb: adenylate cyclase stimulation in human thyroid membrane), thyroglobulin (Tg) levels, and the T3 suppressibility of 24 h RAIU as prognostic markers for the outcome of Graves' disease therapy. Twenty-four Graves' hyperthyroid patients were treated with high MMI dose (mean +/- SD 60 +/- 19, range 40-120 mg daily), and 25 patients received low MMI dose (17 +/- 4.3, 5-20 mg daily). T3, 75 micrograms daily, was given to both groups of patients for 15 +/- 4 (13-22) months of treatment. After cessation of drug therapy, 31 patients (63%) remained euthyroid for 18 +/- 3 (13-49) months of follow-up, 15 (62.5%) and 16 (64%) patients in the high and low dose groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of RA 131I treatment protocols for Graves' disease

The efficacy of 131I therapy in achieving euthyroidism has been studied in a group of 264 patients followed for up to 10 yr. One hundred and eighty-six were given a dose adjusted for thyroid size and radioactive iodine uptake (Protocol 1), and a second group received the same dosage followed by antithyroid drug therapy plus potassium iodide for 15 days (Protocol 2). At 10-yr follow-up, 50-60% of patients were euthyroid. 25-29% of patients required 2 doses of 131I, and 4-5% required 3 doses. Fewer patients became hypothyroid when their pretreatment FTI was above the average value. More patients became hypothyroid, if their pretreatment test for antimicrosomal antibodies was positive. Patients who required a second dose of radioactive iodide had a significantly greater chance of having worsening of their ophthalmopathy than those who became hypothyroid after the first dose. Treatment with radioactive iodide under either protocol appears to achieve euthyroidism at 10 yr with an incidence higher than that achieved by antithyroid drugs and comparable to that reported for subtotal thyroidectomy.

Thyroid stimulating antibodies: an aid to the strategy of treatment of Graves' disease?

In 1976 we initiated a prospective study to specify the usefulness of thyroid stimulating antibody (TSAb) determinations in predicting the outcome of post-antithyroid drug treatment for Graves' disease. This study was carried out on 55 patients, who were either treated for six (n = 16) or 18 months (n = 39) and followed up for an additional two-year period. TSAb was determined on whole serum in 29 patients before and at the end of treatment, and in 26 patients at the end of treatment only. These determinations were carried out using a sensitive and reproducible microassay based on cAMP accumulation in human thyroid cell cultures. Before treatment, TSAb ranging from 170 to 1529% was present in 28/29 patients and reached significantly low levels at the end of treatment whatever its duration. TSAb was undetectable in 24/55 patients at the end of treatment. 8/16 'short-treated' and 18/39 'long-treated' patients remained in remission. As expected, initial TSAb levels had no predictive value. End-treatment TSAb values, when low (less than 350%) or negative did not correlate with later evolution: in these 39 patients, relapse rate was 41%. In contrast, 13/16 patients with end-treatment TSAb greater than 350% relapsed. Relapses tended to occur earlier in patients with the highest TSAb levels. TSAb determined again during follow-up was negative in each of the 18 patients in remission, and positive in 8/10 patients at the time of relapse, whatever its level at the end of the drug course. This study confirms that only end-treatment TSAb levels are predictive of relapse.(ABSTRACT TRUNCATED AT 250 WORDS)