Treatment of hyperthyroidism with a small single daily dose of methimazole: a prospective long-term follow-up study

Methimazole, an Effective Neutralizing Agent of the Sulfur Mustard Derivative 2-Chloroethyl Ethyl Sulfide

Sulfur mustard (SM), designated by the military as HD, is a highly toxic and dangerous vesicant that has been utilized as a chemical warfare agent since World War I. Despite SM's extensive history, an effective antidote does not exist. The effects of SM are predominantly based on its ability to alkylate important biomolecules. Also, with the potential for a fraction of SM to remain unreacted up to days after initial contact, a window of opportunity exists for direct neutralization of unreacted SM over the days following exposure. In this study, we evaluated the structure-activity relationship of multiple nucleophilic molecules to neutralize the toxic effects of 2-chloroethyl ethyl sulfide (CEES), a monofunctional analogue of SM, on human keratinocyte (HaCaT) cells. Cell viability, relative loss of extracellular matrix adhesions, and apoptosis caused by CEES were measured via MTT, cell-matrix adhesion (CMA), and apoptosis protein marker assays, respectively. A set of five two-carbon compounds with various functional groups served as a preliminary group of first-generation neutralizing agents to survey the correlation between mitigation of CEES's toxic effects and functional group nucleophilicity. Apart from thioacids, which produced additive toxicity, we generally observed the trend of increasing protection from cytotoxicity with increasing nucleophilicity. We extended this treatment strategy to second-generation agents which contained advantageous structural features identified from the first-generation molecules. Our results show that methimazole (MIZ), a currently FDA-approved drug used to treat hyperthyroidism, effectively reduced cytotoxicity, increased CMA, and decreased apoptosis resulting from CEES toxicity. MIZ selectively reacts with CEES to produce 2-(2-(ethylthio)ethylthio)-1-methyl-1H-imidazole (EEMI) in media and cell lysate treatments resulting in the reduction of toxicity. Based on these results, future development of MIZ as an SM therapeutic may provide a viable approach to reduce both the immediate and long-term toxicity of SM and may also help mitigate slower developing SM toxicity due to residual intact SM.

Clinical efficacy of thyroid-stimulating immunoglobulin detection for diagnosing Graves' disease and predictors of responsiveness to methimazole

BACKGROUND

As thyroid-stimulating immunoglobulins (TSI) are a sign of Graves' disease (GD), measuring TSI titers is becoming increasingly important for GD diagnosis. This study evaluated the diagnostic accuracy of a new fully automated TSI immunoassay (Immulite™ TSI assay) in GD patients and compared it to the third generation thyroid-stimulating hormone receptor antibody (TRAb) electrochemiluminescence assay (Elecsys Anti-TSHR assay). Additionally, clinical characteristics associated with responsiveness to methimazole in patients with newly diagnosed GD were preliminarily explored.

METHODS

This study involved 324 subjects, comprising patients with untreated GD (GD-UT), Graves' ophthalmopathy (GO) patients, GD patients who had been treated for > 12 months (GD-T), autoimmune thyroiditis (AIT) patients, and healthy subjects (HS). The Immulite™ TSI and Elecsys Anti-TSHR assay were performed on all samples. According to their responsiveness to methimazole, the GD-UT patients were divided into rapid and slow responder groups, and their clinical characteristics were compared.

RESULTS

A receiver operating characteristic (ROC) curve analysis of GD-UT patients showed that the optimal TSI cut-off value was 0.57 IU/L. Logistic regression revealed that age and initial FT4 and TSI levels in the middle-dose methimazole group were related to a rapid response, while the initial FT4 level, but not TSI, in the high-dose group was also associated with a rapid response.

CONCLUSIONS

The clinical diagnostic performance of the Immulite™ TSI assay for diagnosing GD was comparable to that of the Elecsys Anti-TSHR assay. The initial FT4 and TSI levels can be used as predictors of the responsiveness to methimazole in patients with newly diagnosed GD.

Pharmacodynamic Response to Anti-thyroid Drugs in Graves' Hyperthyroidism

Objective: Graves' disease is the commonest cause of hyperthyroidism in populations with sufficient dietary iodine intake. Anti-thyroid drugs (ATD) are often used as the initial treatment for Graves' hyperthyroidism, however there is a paucity of data relating the dose of ATD therapy to the effect on thyroid hormone levels, increasing the risk of both over- and under-treatment. We aimed to determine the pharmacodynamic response to the ATD carbimazole. Design: Retrospective cohort study. Methods: Participants were patients (n = 441) diagnosed with Graves' disease at Imperial College Healthcare NHS Trust between 2009 and 2018. The main outcome measure was change in thyroid hormone levels in response to ATD. Results: Baseline thyroid hormone levels were positively associated with TSH receptor antibody titres (P < 0.0001). Baseline free triiodothyronine (fT3) were linearly related to free thyroxine (fT4) levels in the hyperthyroid state (fT3 = fT4^*0.97-11), and fell proportionately with carbimazole. The percentage falls in fT4 and fT3 per day were associated with carbimazole dose (P < 0.0001). The magnitude of fall in thyroid hormones after the same dose of carbimazole was lower during follow up than at the initiation visit. The fall in thyroid hormone levels approximated to a linear response if assessed at least 3 weeks after commencement of carbimazole. Following withdrawal of antithyroid drug treatment, the risk of relapse was greater in patients with higher initial fT4, initial TSH receptor antibody titre, males, smokers, and British Caucasian ethnicity. Conclusion: We identify a dose-response relationship for fall in thyroid hormones in response to carbimazole to aid in the selection of dose for Graves' hyperthyroidism.

Safety of long-term antithyroid drug treatment? A systematic review

Continued low-dose MMI treatment for longer than 12-18 months may be considered in patients not in remission. However, ATDs are not free from adverse effects. We undertook a systematic review to clarify safety of long-term ATD treatment. Medline and the Cochrane Library for trials published between 1950 and Nov 2018 were systematically searched. We included original studies containing data for long-term (> 18 months) ATD treatment. Two reviewers independently extracted data from included trials and any disagreement was adjudicated by consensus. Of 615 related articles found, 12 fulfilled the criteria. Six articles had data for adults, five for non-adults and one article had data for both groups. The sample sizes ranged between 20 and 249 individuals, and the mean duration of ATD treatment ranged between 2.1 and 14.2 years. Considering all data from 1660 patients treated with ATD for a mean duration of 5.8 years (around 10,000 patient-years), major complications occurred only in 14 patients: 7 severe agranulocytosis, 5 severe liver damage, one ANCA-associated glomerulonephritis and one vasculitis with small cutaneous ulcerations. Minor complications rates were between 2 and 36%, while more complications were in higher doses and in the children. The most reported AE was cutaneous reaction; the other adverse events were elevated liver enzymes, leukocytopenia, arthritis, arthralgia, myalgia, thrombocytopenia, fever, nausea and oral aphthous. Long-term ATD treatment is safe, especially in low dose and in adults, indicating that it should be considered as an earnest alternative treatment for GD.

Free Thyroxine, Anti-Thyroid Stimulating Hormone Receptor Antibody Titers, and Absence of Goiter Were Associated with Responsiveness to Methimazole in Patients with New Onset Graves' Disease

BACKGROUND

Anti-thyroid drug therapy is considered a treatment of choice for Graves' disease; however, treatment response varies among individuals. Although several studies have reported risk factors for relapse after initial treatment, few have assessed responsiveness during the early treatment period. Our study aimed to identify the clinical characteristics for responsiveness to methimazole.

METHODS

We included 99 patients diagnosed with Graves' disease for the first time. Drug responsiveness was defined as the correlation coefficients between decreasing rates of free thyroxine level per month and methimazole exposure dose. According to their responsiveness to treatment, the patients were classified into rapid or slow responder groups, and age, sex, free thyroxine level, and thyrotropin binding inhibiting immunoglobulin (TBII) titers were compared between groups.

RESULTS

The mean patient age was 44.0±13.5 years and 40 patients were male (40%). The mean TBII titer was 36.6±74.4 IU/L, and the mean free thyroxine concentration was 48.9±21.9 pmol/L. The rapid responder group showed higher TBII titer and free thyroxine level at diagnosis, while age, sex, smoking, and presence of goiter did not differ between the two groups. Logistic regression analyses revealed that high level of serum thyroxine, high titer of TBII, and absence of goiter were significantly associated with a rapid response, while age, sex, and smoking were not significant factors for the prediction of responsiveness.

CONCLUSION

In patients with new onset Graves' disease, high level of free thyroxine, high titer of TBII, and absence of goiter were associated with rapid responsiveness to methimazole treatment.

Efficacy of Once Daily versus Divided Daily Administration of Low Daily Dosage (15 mg/Day) of Methimazole in the Induction of Euthyroidism in Graves' Hyperthyroidism: A Randomized Controlled Study

BACKGROUND

Previous studies used unequal or high daily dosages of methimazole (MMI) to compare the efficacy of once daily dose regimen (OD-MMI) with that of divided daily doses regimen (DD-MMI) in inducing euthyroidism.

OBJECTIVES

To compare the efficacy of OD-MMI to that of DD-MMI using low daily dosage of MMI in inducing euthyroidism.

METHODS

Fifty patients with clinically nonsevere Graves' hyperthyroidism were randomized to be treated with 15 mg/day OD-MMI or 15 mg/day DD-MMI.

RESULTS

21 cases (84%) in OD-MMI and 23 cases (92%) in DD-MMI were eligible for analyses. During the treatment, there was no difference in baseline characteristics, serum FT3 and FT4 reductions, and cumulative rate of achieving euthyroidism (4.8% versus 4.3%, 28.6% versus 34.8%, 71.4% versus 82.6%, and 85.7% versus 87.0% at 2, 4, 8, and 12 weeks, resp.) between both regimens. Hypothyroidism developed in DD-MMI significantly more than in OD-MMI (17.4% versus 0%, p < 0.05).

CONCLUSIONS

Treatment with MMI at a low daily dosage of 15 mg/day OD-MMI is as effective as DD-MMI in the reduction of serum thyroid hormone levels and induction of euthyroidism. The OD-MMI regimen is preferable to the DD-MMI regimen in the treatment of clinically nonsevere Graves' hyperthyroidism. This trial is registered with Thai Clinical Trials Registry: TCTR20170529001.

Outpatient 131I Treatment for a Patient with Graves' Disease Receiving Hemodialysis

A patient presented with hyperthyroidism and end-stage renal disease requiring hemodialysis that was difficult to control despite increased dosages of anti-thyroid drugs. The condition could finally be controlled by ¹³¹I radioactive iodine therapy (RIT) and hemodialysis provided under a hospital-linkage system. During three hemodialysis sessions after the oral administration of ¹³¹I, we measured the radioactivity released from the patient and the radioactivity of the devices/tools used. The radioactivity of the devices/tools was managed by allowing the isotope to decay into non-radioactive elements. Our experience suggests that outpatient RIT may provide a safe and convenient means of treating Graves' disease, even in patients receiving hemodialysis.

Induction of thyroid remission using rituximab in a patient with type 3 autoimmune polyglandular syndrome including Graves' disease and type 1 diabetes mellitus: a case report

Rituximab (RTX) is a monoclonal antibody that targets the B-cell-specific CD20 antigen. Recent reports indicate that RTX is effective against type 1 diabetes mellitus (T1DM) and hematologic as well as autoimmune diseases. Other studies have indicated that RTX therapy leads to the remission of recurrent or active Graves' disease (GD). However, the efficacy of RTX in Japanese patients with autoimmune polyglandular syndrome (APS) has not been reported to date. Herein, we report the case of a patient with GD and T1DM with sustained endogenous insulin secretion capacity. To protect pancreatic β cells, we administered RTX at a dose of 500 mg (approximately 300 mg/m2) on 2 occasions 1 week apart. After treatment, no adverse effects were observed, and thyroid stimulating hormone receptor antibody (TRAb) was no longer detectable 4 months after RTX administration. In addition, the reduction in TRAb level improved thyroid function. Notably, the treatment induced remission over a period of 1 year after the diagnosis of GD.

Comparison of efficacy and adverse effects between methimazole 15 mg+inorganic iodine 38 mg/day and methimazole 30 mg/day as initial therapy for Graves' disease patients with moderate to severe hyperthyroidism

BACKGROUND

Methimazole (MMI) is usually used at an initial dose of 30 mg/day for severe Graves' disease (GD) hyperthyroidism, but adverse effects are more frequent at this dose than at MMI 15 mg/day.

OBJECTIVES

We designed a regimen to address the lack of a primary therapeutic effect of the MMI 15 mg/day by combining it with inorganic iodine at 38.2 mg/day. Our aim was to compare the two regimens (MMI 15 mg+inorganic iodine at 38.2 mg/day (M15+I) vs. MMI 30 mg/day (M30)) in terms of therapeutic effect, adverse effects, and remission rate.

DESIGN AND PATIENTS

In a prospective study, 310 patients with untreated GD (serum free thyroxine (fT4) ≥5 ng/dL) were assigned to one of the two regimens. Potassium iodide was discontinued in the M15+I group as soon as the serum fT4 level was within the reference range (0.8-1.6 ng/dL).

RESULTS

Percentages of patients achieving an fT4 level within reference range in ≤30, ≤60, or 90 days on the study treatment regimens were 45.3%, 73.9%, and 82.0% respectively for the M15+I group, and 24.8%, 63.1%, and 75.2% respectively for the M30 group. Hence, the proportions of patients achieving this goal in ≤30 or ≤60 days were significantly larger in the M15+I group. Adverse effects that required discontinuation of MMI were more frequent in the M30-treated than in the M15+I-treated group (14.8% vs. 7.5%; p=0.0387). The remission rates in the M15+I and M30 groups were 19.9% and 14.8%-higher in the former, but the difference did not reach statistical significance.

CONCLUSION

The results of this study raise the possibility that M15+I is superior to M30 as a primary treatment for moderate to severe hyperthyroidism caused by GD.

Comparison of methimazole and propylthiouracil in the management of children and adolescents with Graves' disease: efficacy and adverse reactions during initial treatment and long-term outcome

OBJECTIVE

The aim of this study was to compare the efficacy and adverse reactions during initial treatment and long-term outcome between children and adolescents with Graves' disease (GD) treated with propylthiouracil (PTU) and those treated with methimazole (MMI).

DESIGN, SETTING AND PARTICIPANTS

Retrospective and collaborative study. Children and adolescents with GD were divided into group M (MMI: n=64) and group P (PTU: n=69) and into four subgroups by initial dose: group M1 (<0.75 mg/kg of MMI, n=34), group M2 (> or = 0.75 mg/kg, n=30), group P1 (<7.5 mg/kg of PTU, n=24) and group P2 (> or = 7.5 mg/kg, n=45).

MAIN OUTCOME MEASURES

The duration for normalization of serum T4 on initial treatment, the incidence of adverse effects for one year and outcomes at 10 years after were compared.

RESULTS

Mean durations for normalization of T4 (+/- SD) were 1.7 +/- 1.0 months in group M and 2.3 +/- 2.4 in group P [not significant (NS)], while the mean duration in group P1 (3.1 +/- 3.3) was significantly longer than those in the other subgroups (M1: 1.9 +/- 1.2; M2: 1.4 +/- 0.7; P2; 1.7 +/- 1.3). No major adverse reaction was observed. Minor adverse effects occurred in 25.0% of cases in group M and 31.9% in group P (NS). The incidence in group P2 (44.4%) was significantly higher than those in group M1 (20.6%) and group P1 (8.3%). Remission rates did not differ between the MMI-treated group (35.0%, n=20) and PTU-treated group (50.0%, n=40).

CONCLUSIONS

PTU may not be suitable for initial use in children and adolescents with GD, even with the risk of major adverse reactions such as liver failure excluded.

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.

Benefit of short-term iodide supplementation to antithyroid drug treatment of thyrotoxicosis due to Graves' disease

OBJECTIVE

Combined treatment with anti-thyroid drugs (ATDs) and potassium iodide (KI) has been used only for severe thyrotoxicosis or as a pretreatment before urgent thyroidectomy in patients with Graves' disease. We compared methimazole (MMI) treatment with MMI + KI treatment in terms of rapid normalization of thyroid hormones during the early phase and examined the later induction of disease remission.

DESIGN AND PATIENTS

A total of 134 untreated patients with Graves' disease were randomly assigned to one of four regimens: Group 1, MMI 30 mg; Group 2, MMI 30 mg + KI; Group 3, MMI 15 mg and Group 4, MMI 15 mg + KI. For easy handling, KI tablets were used instead of saturated solution of KI. KI was discontinued when patients showed normal free thyroxine (FT4) levels but MMI was continued with a tapering dosage until remission. Remission rate was examined during a 4- to 5-year observation.

MEASUREMENTS

Serum FT4, FT3 and TSH were measured by chemiluminescent immunoassays. TSH receptor antibody (TRAb) was assayed with TRAb-ELISA. Goitre size was estimated by ultrasonography.

RESULTS

After 2 weeks of treatment, normal FT4 was observed in 29% of patients in Group 1 and 59% (P < 0.05) of patients in Group 2. Furthermore, normal FT4 after 2 weeks of treatment was observed in 27% of patients in Group 3 and 54% (P < 0.05) of patients in Group 4. Similarly, FT3 normalized more rapidly in Groups 2 and 4 than in Groups 1 and 3. None of the patients showed an increase in thyroid hormones or aggravation of disease during combined treatment with MMI and KI. The remission rates in Groups 1, 2, 3 and 4 were 34%, 44%, 33% and 51%, respectively, and were higher in the groups receiving combined therapy but differences among four groups did not reach significance.

CONCLUSIONS

Combined treatment with MMI and KI improved the short-term control of Graves' hyperthyroidism and was not associated with worsening hyperthyroidism or induction of thionamide resistance.

Methimazole-induced agranulocytosis in patients with Graves' disease is more frequent with an initial dose of 30 mg daily than with 15 mg daily

BACKGROUND

Antithyroid drugs (ATDs) are prescribed as the initial therapy for the majority of patients with Graves' disease in many areas of the world. Although, it is well known that agranulocytosis is one of the most serious side effects of ATDs, there has not yet been any conclusive evidence that the prevalence of agranulocytosis induced by ATDs is dose related. This study was performed to determine if the prevalence of agranulocytosis is different depending on the starting dosage of ATDs in patients with Graves' disease.

METHODS

Until 1996, we had typically prescribed 30 mg/d of methimazole (MMI) as the initial dosage for the treatment of Graves' disease at our institution. We changed the initial MMI dosage to 15 mg/d as a general rule in 1997. As a consequence, we acquired two groups of patients with Graves' disease who received different dosages of MMI. We retrospectively compared the prevalence of MMI-induced agranulocytosis in patients who received 15 mg/d of MMI to those who received 30 mg/d of MMI.

RESULTS

There were 2087 subjects treated with 30 mg/d of MMI and 2739 treated with 15 mg/d of MMI. The prevalence of agranulocytosis in the 30 mg/d group was significantly higher than in the 15 mg/d group (0.814% vs. 0.219%, respectively, p < 0.01). The prevalence of agranulocytosis plus neutropenia in the 30 mg/d group was also significantly higher than in the 15 mg/d group (1.581% vs. 0.474%, respectively, p < 0.001).

CONCLUSIONS

It is very likely that MMI-induced agranulocytosis occurs with a larger dosage of MMI and is dose related. Considering both the effectiveness and the risk of serious side effects, we recommend 15 mg/d of MMI as the starting dosage for the treatment of Graves' disease.

Long-term maintenance of low-dose antithyroid drugs versus drug withdrawal in patients with Graves' hyperthyroidism

OBJECTIVE

The relapse rate of Graves' hyperthyroidism after finishing an antithyroid cicle is high. The objective of this work was to prospectively investigate the relapse rate of Graves' hyperthyroidism (GH) in patients with maintenance of a low dose of antithyroid drug (ATD) therapy.

PATIENTS AND METHOD

From March 1997, all patients with GH consecutively attending the same center who remained euthyroid with low doses of synthetic ATD (carbimazole or methimazole: 2.5-5mg/day) on 2 consecutive follow-up visits (at 10-12 months) were included in this study. Instead of withdrawing ATD, the aim was to continue with this low dose for a 5-year period (group M: 53 patients). From March 1997, data were also collected from patients with GH who were consecutively followed-up and who, meeting the criteria for inclusion in group M, had stopped receiving ATD before the start of the study (March 1997) (group R: 31 patients).

MAIN OUTCOME

GH relapse was observed in 12/53 patients in group M (22.64%) and in 24/31 patients in group R (77.42%) (p<0.000).

CONCLUSIONS

The GH relapse rate was significantly lower with long-term maintenance of a low dose of ATD than with therapy withdrawal.

Pharmacologic Management of Feline Hyperthyroidism

Radioiodine is considered the treatment of choice for hyperthyroidism, but in some situations, methimazole therapy is preferred, such as in cats with preexisting renal insufficiency. Unfavorable outcomes from methimazole are usually attributable to side effects, such as gastrointestinal upset, facial excoriation, thrombocytopenia, neutropenia, or liver enzyme elevations. Because restoration of euthyroidism can lead to a drop in glomerular filtration rate, all cats treated with methimazole should be monitored with blood urea nitrogen and creatinine levels in addition to serum thyroxine (T(4)) and a complete blood cell count. Transdermal methimazole is associated with fewer gastrointestinal side effects and can be used in cats with simple vomiting or inappetence from oral methimazole. Hypertension may not resolve immediately when serum T(4) is normalized, and moderate to severe hypertension should be treated concurrently with atenolol, amlodipine, or an angiotensin-converting enzyme inhibitor.

Comparison of methimazole and propylthiouracil in patients with hyperthyroidism caused by Graves' disease

CONTEXT

Although methimazole (MMI) and propylthiouracil (PTU) have long been used to treat hyperthyroidism caused by Graves' disease (GD), there is still no clear conclusion about the choice of drug or appropriate initial doses.

OBJECTIVE

The aim of the study was to compare the MMI 30 mg/d treatment with the PTU 300 mg/d and MMI 15 mg/d treatment in terms of efficacy and adverse reactions.

DESIGN, SETTING, AND PARTICIPANTS

Patients newly diagnosed with GD were randomly assigned to one of the three treatment regimens in a prospective study at four Japanese hospitals.

MAIN OUTCOME MEASURES

Percentages of patients with normal serum free T(4) (FT4) or free T(3) (FT3) and frequency of adverse effects were measured at 4, 8, and 12 wk.

RESULTS

MMI 30 mg/d normalized FT4 in more patients than PTU 300 mg/d and MMI 15 mg/d for the whole group (240 patients) at 12 wk (96.5 vs. 78.3%; P = 0.001; and 86.2%, P = 0.023, respectively). When patients were divided into two groups by initial FT4, in the group of the patients with severe hyperthyroidism (FT4, 7 ng/dl or more, 64 patients) MMI 30 mg/d normalized FT4 more effectively than PTU 300 mg/d at 8 and 12 wk and MMI 15 mg/d at 8 wk, respectively (P < 0.05). No remarkable difference between the treatments was observed in patients with initial FT4 less than 7 ng/dl. Adverse effects, especially mild hepatotoxicity, were higher with PTU and significantly lower with MMI 15 mg/d compared with MMI 30 mg/d.

CONCLUSIONS

MMI 15 mg/d is suitable for mild and moderate GD, whereas MMI 30 mg/d is advisable for severe cases. PTU is not recommended for initial use.

The relation of initial methimazole dose to the incidence of methimazole-induced agranulocytosis in patients with Graves' disease

The relation between the incidence of methimazole (methylmercaptoimidazole; MMI)-induced agranulocytosis and initial MMI dose was evaluated in a group of 514 patients with Graves' disease who were treated between 1995 and 2005. One hundred and forty-six (28.40%) patients had received an initial dose of 30 mg MMI and 277 (53.89%) patients had been treated with 15 mg MMI. Nine patients (1.75%) developed agranulocytosis due to MMI treatment. Six (4.11%) of 146 patients who received an initial dose of 30 mg MMI, two (4.54%) of 44 patients given an initial dose of 20 mg MMI, and one (0.36%) of 277 patients given an initial dose of 15 mg MMI developed agranulocytosis. There was a statistically significant difference in agranulocytosis incidence between patients receiving an initial dose of 30 mg MMI and those who received an initial dose of 15 mg. Although 8 (4.10%) of 195 patients in the high-dose group (20 mg or higher) developed agranulocytosis, only 1 (0.31%) of 319 patients in the low-dose group (15 mg or lower) did. In conclusion, the incidence of agranulocytosis with low-dose MMI therapy was ten times lower than that of the high-dose regimen.

The treatment of Graves' disease in children

Graves' disease is the most common form of hyperthyroidism in childhood. Current treatment options include antithyroid medications, surgery, and radioactive iodine. Medical therapy is generally associated with long-term remission rates of less than 25% and a small risk of serious adverse reactions that include hepatic failure and bone marrow suppression. Total thyroidectomy is associated with very high cure rates and a small risk of hypoparathyroidism and recurrent laryngeal nerve damage. When radioactive iodine is used at appropriate doses, there is a very high cure rate without increased risks of thyroid cancer or genetic damage. Clinicians caring for the child or adolescent with Graves' disease are thus faced with using medications with potential short-term and long-term toxicity, for a condition in which spontaneous remission occurs in the minority of pediatric patients. Definitive therapy in the form of surgery or radioactive iodine is necessary and unavoidable for the majority of pediatric patients with Graves' disease.

TSH receptor antibody measurements and prediction of remission in Graves' disease patients treated with minimum maintenance doses of antithyroid drugs

Prediction of remission is one of the main problems of antithyroid drug (ATD) therapy for Graves' disease especially in patients who are treated with a minimum maintenance dose of ATD. We evaluated the ability of new sensitive TSH receptor antibody (TRAb) assays to predict remission in Graves' patients using two commercially available kits (TRAb-CT from Cosmic Corporation and TRAb-Dyno from Yamasa Corporation), compared to the original PEG assay. When a euthyroid state was achieved for more than 6 months with methimazole 5 mg/day or propylthiouracil 50 mg/day and thereafter for three months with 5 mg every other day or 50 mg every other day, respectively, we discontinued ATD medication. One year of observation after discontinuation of ATD was completed in 71 patients (60 females, median age 43 years, range 18-71), and TRAb values from these patients were analyzed in relation to prognosis. Twenty-six (37%) of the 71 patients had relapse of thyrotoxicosis and 45 remained euthyroid. The median TRAb levels in the relapse group were significantly higher than those in the remission group (P < 0.05). Relapse occurred in 15/51 patients negative by TRAb-CT, in 11/20 patients positive by TRAb-CT (chi2 = 4.1; P < 0.05), in 11/42 patients negative by TRAb-Dyno and in 15/29 patients positive by TRAb-Dyno (chi2 = 4.8; P < 0.05). By contrast, relapse occurred in 23/64 patients with negative TRAb by PEG assay and in 3/7 patients with PEG assay positive values (n.s.). All patients with TRAb-CT values of 30% inhibition or greater, or TRAb-Dyno values of 3.0 U/L or greater relapsed during the observation period. Thus, measurement of TRAb by the new sensitive assays is useful for prediction of remission in our patients.

Comparison of single daily dose of methimazole and propylthiouracil in the treatment of Graves' hyperthyroidism

OBJECTIVE

The present study was to compare the efficacy of a single daily dose of methimazole (MMI) and propylthiouracil (PTU) in the treatment of Graves' hyperthyroidism.

BACKGROUND

Antithyroid drugs, MMI and PTU, are widely used in the treatment of hyperthyroidism. Previous studies in the treatment of hyperthyroidism with a single daily dose of antithyroid drugs have demonstrated a more favourable result with MMI. However, the efficacy of a single daily dose of PTU was inconsistent. In this study, we examined the therapeutic efficacy of single daily doses of MMI and PTU on the change of thyroid hormones and thyrotropin receptor antibodies (TRAb) levels.

METHODS

Thirty patients with newly diagnosed Graves' hyperthyroidism were randomly divided into two groups, each receiving a single dose of either 15 mg MMI or 150 mg PTU daily for 12 weeks. The therapeutic efficacy was determined by serum total triiodothyronine (TT3), total thyroxine (TT4), thyrotropin (TSH), free thyroxine (FT4), and TRAb levels at baseline and at the end of 4, 8 and 12 weeks during the study period.

RESULTS

There was no significant difference in baseline thyroid function parameters. Serum TT3, TT4 and FT4 levels in the MMI-treated group were significantly lower than those of the PTU-treated group after 4 weeks and through the end of the study. MMI also has superior effect on reducing serum TRAb levels than PTU after 8 weeks and at the end of the study.

CONCLUSION

During the 12-week treatment of Graves' hyperthyroidism, a single daily dose of 15 mg MMI was much more effective in the induction of euthyroidism than a single daily dose of 150 mg PTU. In the doses used in this study, MMI is preferable to PTU when a once-daily regimen of antithyroid drug is considered for the treatment of Graves' hyperthyroidism.

Diagnosis and treatment of Graves disease

OBJECTIVE

To review the etiology, diagnosis, and clinical presentation of Graves disease and provide an overview of the standard and adjunctive treatments. Specifically, antithyroid drugs, beta-blockers, inorganic iodide, lithium, and radioactive iodine are discussed, focusing on current controversies.

DATA SOURCES

Primary articles were identified through a MEDLINE search (1966-July 2000). Key word searches included beta-blockers, Graves disease, inorganic iodide, lithium, methimazole, and propylthiouracil. Additional articles from these sources and endocrinology textbooks were also identified. We agreed to include articles that would highlight the most relevant points, as well as current areas of controversy.

DATA SYNTHESIS

Graves disease is the most common cause of hyperthyroidism. The 3 main treatment options for patients with Graves hyperthyroidism include antithyroid drugs, radioactive iodine, and surgery. Although the antithyroid drugs propylthiouracil (PTU) and methimazole (MMI) have similar efficacy, there are situations when 1 agent is preferred. MMI has a longer half-life than PTU, allowing once-daily dosing that can improve patient adherence to treatment. PTU has historically been the drug of choice for treating pregnant and breast-feeding women because of its limited transfer into the placenta and breast milk. Adjuvant therapies for Graves disease include beta-blockers, inorganic iodide, and lithium. beta-Blockers are used to decrease the symptoms of hyperthyroidism. Inorganic iodide is primarily used to prepare patients for thyroid surgery because of its ability to decrease the vascularity of the thyroid gland. Lithium, which acts in a manner similar to iodine, is not routinely used due to its transient effect and the risk of potentially serious adverse effects. In the US, radioiodine therapy has become the preferred treatment for adults with Graves disease. It is easy to administer, safe, effective, and more affordable than long-term treatment with antithyroid drugs. Hypothyroidism is an inevitable consequence of radioiodine therapy. Radioiodine is contraindicated in pregnant women because it can damage the fetal thyroid gland, resulting in fetal hypothyroidism. Bilateral subtotal thyroidectomy, which was once the only treatment available, is now performed only in special circumstances. In addition to the normal risks associated with surgery, laryngeal nerve damage, hypoparathyroidism, and hypothyroidism can occur following that procedure.

CONCLUSIONS

Despite extensive experience with medical management, controversy prevails regarding choosing among the various drugs for treatment of Graves disease. None of the treatment options, including antithyroid drugs, radioiodine, and surgery, is ideal. Each has risks and benefits, and selection should be tailored to the individual patient.

Efficacy and safety of once versus twice daily administration of methimazole in cats with hyperthyroidism

OBJECTIVE

To determine whether once daily administration of methimazole was as effective and safe as twice daily administration in cats with hyperthyroidism.

DESIGN

Randomized, nonblinded, clinical trial.

ANIMALS

40 cats with newly diagnosed hyperthyroidism.

PROCEDURE

Cats were randomly assigned to receive 5 mg of methimazole, PO, once daily (n = 25) or 2.5 mg of methimazole, PO, twice daily (15). A complete physical examination, including measurement of body weight; CBC; serum biochemical analyses, including measurement of serum thyroxine concentration; and urinalysis were performed, and blood pressure was measured before and 2 and 4 weeks after initiation of treatment.

RESULTS

Serum thyroxine concentration was significantly higher in cats given methimazole once daily, compared with cats given methimazole twice daily, 2 weeks (3.7 vs 2.0 micro +/- g/dL) and 4 weeks (3.2 vs 1.7 microg/dL) after initiation of treatment. In addition, the proportion of cats that were euthyroid after 2 weeks of treatment was lower for cats receiving methimazole once daily (54%) than for cats receiving methimazole twice daily (87%). Percentages of cats with adverse effects (primarily gastrointestinal tract upset and facial pruritus) were not significantly different between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that once daily administration of methimazole was not as effective as twice daily administration in cats with hyperthyroidism and cannot be recommended for routine use.

Efficacy of single daily dosage of methimazole vs. propylthiouracil in the induction of euthyroidism

OBJECTIVE

Previous studies of the treatment of hyperthyroidism with a single daily dose of antithyroid drugs have demonstrated a favourable result with methimazole (MMI). However, the efficacy of a single daily dose of propylthiouracil (PTU) was inconsistent. The present prospective randomized study was conducted to compare the efficacy of a single daily dose of MMI and PTU in the induction of euthyroidism in patients with Graves' disease.

SUBJECTS

Seventy-one patients with newly diagnosed Graves' disease were studied.

METHODS AND MEASUREMENTS

Patients were randomized to two groups to receive once daily dose of either 15 mg MMI or 150 mg PTU for 12 weeks. The therapeutic efficacy was determined biochemically by serum total T3, total T4 and TSH levels at baseline and at 4, 8 and 12 weeks during the study period.

RESULTS

There was no significant difference in baseline characteristics. Serum total T3 levels of the MMI group were significantly lower than those of the PTU group after four weeks of the treatment (3.54 +/- 0.72 vs. 5.49 +/- 2.74 nmol/l, P < 0.05) through the end of the study (2.22 +/- 1.42 vs. 4.30 +/- 1.78 nmol/l, P < 0.05). The changes in serum total T4 levels occurred in the same direction as serum total T3 levels but a significant difference was observed only after eight weeks of the treatment (MMI vs. PTU; 101.67 +/- 54.05 vs. 176.32 +/- 66.92 nmol/l, P < 0.05). At the end of the study, more patients in the MMI group had both serum total T3 and T4 levels less than the upper limit of the normal range compared to the PTU group (77.1% vs. 19.4%). Hypothyroidism was observed in 31.4% of the patients in the MMI group but not in the PTU group.

CONCLUSIONS

During 12-weeks' treatment of Graves' hyperthyroidism, a single daily dose of 15 mg of MMI was much more effective in the induction of euthyroidism than a single daily dose of 150 mg of PTU. Once daily regimen of MMI not only decreased serum T3 and T4 levels more rapidly but also induced euthyroidism four times more effectively than did the once daily regimen of PTU. In the doses used in this study, MMI is preferable to PTU when a once-daily regimen of antithyroid drug is considered for the treatment of hyperthyroidism.

Surgical treatment of hyperthyroidism: a ten-year experience

Hyperthyroidism is treated either by antithyroid drugs, radioiodine (I131) or surgery. In Sweden, surgery is often performed in patients with large goiter or severe hyperthyroidism with infiltrative endocrine ophthalmopathy. To evaluate indications and results of surgical treatment, data from 380 patients operated on for hyperthyroidism at our department during 1986-1995 were analyzed. Twenty-six percent were referred for surgery because of failure of treatment with antithyroid drugs or I131. Ninety-one percent were subjected to subtotal thyroidectomy with a median remnant weight of less than 2 g. In the remaining patients, total thyroidectomy was performed. Transient vocal cord affection occurred in 2.6%, none of which was permanent. Prolonged postoperative hypocalcemia occurred in 3.1%, and permanent hypoparathyroidism in 1%. There was no difference in complication rate between subtotal or total thyroidectomy. In patients with Graves' disease, 5% worsened with regard to ophthalmopathy initially after surgery but later improved. Recurrent disease occurred in 2% of the patients, all of whom had undergone subtotal thyroidectomy. Surgery is not first-line therapy in all patients with hyperthyroidism. However, in experienced hands, surgery is a good therapeutic alternative that can be carried out with no mortality, few complications, and, provided that a minimal remnant is left, very few recurrences.