A case of hypersensitivity syndrome induced by methimazole for Graves' disease

Drug-induced hypersensitivity syndrome is one of the most severe forms of drug eruption and is characterized by high fever and multiorgan involvement. Reactivation of human herpesvirus-6 (HHV-6) or cytomegalovirus (CMV) has been suggested to be involved in this syndrome, although the exact role of these viruses remains elusive. We report the case of a 50-year-old Japanese male with Graves' disease who developed hypersensitivity syndrome caused by the antithyroid drug methimazole (MMI). After treatment with MMI 30 mg three times daily for 1(1/2) months, the patient developed generalized exfoliative erythematous eruption and high fever. Cessation of treatment with the drug improved his condition. Readministration of MMI worsened his clinical features. Treatment with high-dose methylprednisolone for 6 days and subsequent administration of prednisolone 20 mg twice daily improved his clinical manifestations. Elevated titers of anti-HHV-6 immunoglobulin G (IgG) and anti-CMV IgG antibodies were observed, and these gradually decreased during the clinical course, indicating reactivation of HHV-6 and CMV. Drug-induced lymphocyte stimulation test for MMI was negative. This is the first reported case of MMI-induced hypersensitivity syndrome associated with the reactivation of HHV-6 and CMV.

Clinical and laboratory characteristics of drug-induced vasculitic syndromes

Clinical recognition of drug-induced vasculitic and lupus-like syndromes is very important because continued use of the offending drug can lead to irreversible and life-threatening vasculitic organ damage (e.g. end-stage renal disease or pulmonary haemorrhage). Withdrawal of the drug often leads to spontaneous recovery, meaning that immunosuppressive therapy can be avoided. The presence of myeloperoxidase–antineutrophil cytoplasmic antibodies, IgM anticardiolipin antibody, and antihistone antibodies in combination was found to be characteristic of drug-induced vasculitic syndromes caused by the antithyroid drugs propylthiouracil and methimazol. Clinically, skin vasculitis and arthralgias predominated and renal vasculitis was rare.

[Effects of maternal hyperthyroidism and antithyroid drug therapy on congenital malformation of newborn infants]

OBJECTIVE

To evaluate the relationship between the incidence of congenital malformations of newborns and maternal hyperthyroidism with antithyroid drug (ATD) therapy during pregnancy.

METHODS

The clinical data of 100 cases of pregnant women with hyperthyroidism and their 101 offsprings born in Peking Union Medical College Hospital during 1983-2003 were analyzed retrospectively. According to the maternal thyroid function, and antithyroid drugs taken during the first trimester of pregnancy, subjects were divided into different groups. The incidence of congenital malformations of newborns and risk factors, especially the effects of maternal hyperthyroidism with antithyroid drug therapy were analysed.

RESULTS

The prevalence of congenital malformation in infants born to mothers who had hyperthyroidism during pregnancy (6.9%, 7/101) was significantly higher than that of all the infants born in the same hospital during the same period (0.9%, 212/22 765, P < 0.01). The difference of the incidence of malformed infants born to mothers with hyperthyroidism (9.6%, 5/52) or euthyroidism (4.1%, 2/49) during the first trimester was not significant (P > 0.05). The incidence of malformed infants whose mothers received methimazole (MMI; 41.7%, 5/12) was significantly higher than that of mothers treated with propylthiouracil (PTU) (3.6%, 1/28) and without ATDs (1.6%, 1/61), respectively (P < 0.01). The Loglinear model analyses showed that mothers receiving MMI during the first trimester of pregnancy was independent risk factor for the increased incidence of malformation of their infants (L.R. square = 15.668, P = 0.0003).

CONCLUSIONS

The risk of congenital malformation in infants whose mothers take MMI during the first trimester may be increased. Therefore, we suggest that MMI should not be used as a choice of drug in treatment of pregnant women with hyperthyroidism.

Antineutrophil cytoplasmic antibody (ANCA)-associated autoimmune diseases induced by antithyroid drugs: comparison with idiopathic ANCA vasculitides

Clinical and serological profiles of idiopathic and drug-induced autoimmune diseases can be very similar. We compared data from idiopathic and antithyroid drug (ATD)-induced antineutrophil cytoplasmic antibody (ANCA)-positive patients. From 1993 to 2003, 2474 patients were tested for ANCA in the Laboratory for Allergy and Clinical Immunology in Belgrade. Out of 2474 patients, 72 (2.9%) were anti-proteinase 3 (PR3)- or anti-myeloperoxidase (MPO)-positive and their clinical and serological data were analyzed. The first group consisted of ANCA-associated idiopathic systemic vasculitis (ISV) diagnosed in 56/72 patients: 29 Wegener's granulomatosis (WG), 23 microscopic polyangiitis (MPA) and four Churg-Strauss syndrome. The second group consisted of 16/72 patients who became ANCA-positive during ATD therapy (12 receiving propylthiouracil and four receiving methimazole). We determined ANCA and antinuclear (ANA) antibodies by indirect immunofluorescence; PR3-ANCA, MPO-ANCA, anticardiolipin (aCL) and antihistone antibodies (AHA) by ELISA; and cryoglobulins by precipitation. Complement components C3 and C4, alpha-1 antitrypsin (α1 AT) and C reactive protein (CR-P) were measured by nephelometry. Renal lesions were present in 3/16 (18.8%) ATD-treated patients and in 42/56 (75%) ISV patients (p <0.001). Skin lesions occurred in 10/16 (62.5%) ATD-treated patients and 14/56 (25%) ISV patients (p <0.01). ATD-treated patients more frequently had MPO-ANCA, ANA, AHA, aCL, cryoglobulins and low C4 (p <0.01). ISV patients more frequently had low α1 AT (p = 0.059) and high CR-P (p <0.001). Of 16 ATD-treated patients, four had drug-induced ANCA vasculitis (three MPA and one WG), while 12 had lupus-like disease (LLD). Of 56 ISV patients, 13 died and eight developed terminal renal failure (TRF). There was no lethality in the ATD-treated group, but 1/16 with methimazole-induced MPA developed pulmonary-renal syndrome with progression to TRF. ANCA-positive ISV had a more severe course in comparison with ATD-induced ANCA-positive diseases. Clinically and serologically ANCA-positive ATD-treated patients can be divided into two groups: the first consisting of patients with drug-induced WG or MPA which resemble ISV and the second consisting of patients with LLD. Different serological profiles could help in the differential diagnosis and adequate therapeutic approach to ANCA-positive ATD-treated patients with symptoms of systemic disease.

Agranulocytosis with tonsillitis associated with methimazole therapy

The treatment of hyperthyroidism with antithyroid drugs can cause a significant side effect in 0.2 to 0.3% of the cases: agranulocytosis. Infectious complications caused by this condition affect mainly the throat, and tonsillitis is one of its manifestations. The present study reported the case of a female patient, 33 years old, manifesting odynophagia and fever resistant to many antibiotics. The patient showed hyperthyroidism and had been using methimazole for two months. With the diagnoses of agranulocytic angina, the drug was withdrawn and treatment with ciprofloxacin, symptomatic drugs and granulocytic-colony stimulator, besides fluconazol was started. The patient developed satisfactorily, being discharged ten days after the beginning of the treatment. Fifteen days later, total thyroidectomy was carried out. The purpose of this report was to point out the importance of knowing the side effects of drugs to advise the patients about them and to warn physicians about the need for evaluating the patient as a whole, searching for other current diseases and drugs in use.

Effect of long-term continuous methimazole treatment of hyperthyroidism: comparison with radioiodine

OBJECTIVE

To investigate the long-term effects of continuous methimazole (MMI) therapy.

DESIGN AND METHODS

Five hundred and four patients over 40 years of age with diffuse toxic goiter were treated with MMI for 18 months. Within one year after discontinuation of MMI, hyperthyroidism recurred in 104 patients. They were randomized into 2 groups for continuous antithyroid and radioiodine treatment. Numbers of occurrences of thyroid dysfunction and total costs of management were assessed during 10 years of follow-up. At the end of the study, 26 patients were still on continuous MMI (group 1), and of 41 radioiodine-treated patients (group 2), 16 were euthyroid and 25 became hypothyroid. Serum thyroid and lipid profiles, bone mineral density, and echocardiography data were obtained.

RESULTS

There was no significant difference in age, sex, duration of symptoms and thyroid function between the two groups. No serious complications occurred in any of the patients. The cost of treatment was lower in group 1 than in group 2. At the end of 10 years, goiter rate was greater and antithyroperoxidase antibody concentration was higher in group 1 than in group 2. Serum cholesterol and low density lipoprotein-cholesterol concentrations were increased in group 2 as compared with group 1; relative risks were 1.8 (1.12-2.95, P<0.02) and 1.6 (1.09-2.34, P<0.02) respectively. Bone mineral density and echocardiographic measurements were not different between the two groups.

CONCLUSION

Long-term continuous treatment of hyperthyroidism with MMI is safe. The complications and the expense of the treatment do not exceed those of radioactive iodine therapy.

Outcome of radioiodine-131 therapy in hyperfunctioning thyroid nodules: a 20 years' retrospective study

OBJECTIVE

To investigate the risk of hypothyroidism after radioiodine (131I) treatment for hyperfunctioning thyroid nodules.

DESIGN

Retrospective analysis of patients treated with 131I for hyperfunctioning thyroid nodules and followed up for a maximum of 20 years.

PATIENTS

A total of 346 patients treated with 131I in the years 1975-95, for a single hyperfunctioning nodule.

MEASUREMENTS

Hypothyroidism was defined as TSH levels > 3.7 mU/l. Kaplan-Meier survival analysis was used to analyse permanence of euthyroidism after 131I. A stepwise Cox proportional hazard model was used to identify factors influencing the progression to hypothyroidism.

RESULTS

The cumulative incidence of hypothyroidism was 7.6% at 1 year, 28% at 5 years, 46% at 10 years and 60% at 20 years. Age (P < 0.01), 24-th 131I uptake (P < 0.05) and previous treatment with methimazole (MMI, P < 0.1) were associated with a faster progression towards hypothyroidism, while thyroid and nodule size, thyroid status at diagnosis and degree of extranodular thyroid parenchymal suppression had no influence. In hyperthyroid patients with partial parenchymal suppression, however, previous MMI treatment was the most important prognostic factor (P < 0.01).

CONCLUSIONS

After 20 years of follow-up, 60% of patients treated with 131I for a single hyperfunctioning nodule are hypothyroid. Factors increasing the risk of hypothyroidism are age, 131I uptake and MMI pretreatment. The prognostic value of this last factor, however, depends on the degree of suppression of the extranodular thyroid parenchyma at the scan.

Efficacy and safety of transdermal methimazole in the treatment of cats with hyperthyroidism

The objective of this study was to determine whether transdermal methimazole was as safe and effective as oral methimazole for the control of hyperthyroidism in cats. Forty-seven cats with newly diagnosed hyperthyroidism were randomized to receive either transdermal methimazole in pluronic lecithin organogel (PLO; applied to the inner pinna), or oral methimazole (2.5 mg q12h for either route). Cats were evaluated at weeks 0, 2, and 4 with a physical exam, body weight determination, CBC, biochemical panel, urinalysis, measurement of total levothyroxine (T4) concentration, indirect Doppler blood pressure determinaiton, and completion of an owner questionnaire. Data between the 2 groups and over time were compared by nonparametric methods. Forty-four cats followed the protocol (17 oral and 27 transdermal). Significantly more cats treated with oral methimazole had serum T4 concentrations within the reference range after 2 weeks (14 of 16 cats) compared to those treated by the transdermal route (14 of 25; P = .027). This difference was no longer significant by 4 weeks of treatment (9 of 11 for oral versus 14 of 21 for transdermal), possibly because of inadequate numbers evaluated by 4 weeks. Cats treated with oral methimazole had a higher incidence of gastrointestinal (GI) adverse effects (4 of 17 cats) compared to the cats treated with transdermal methimazole (1 of 27; P = .04), but no differences were found between groups in the incidence of neutropenia, hepatotoxicity, or facial excoriations. Although the overall efficacy of transdermal methimazole is not as high as that of oral methimazole at 2 weeks of treatment, it is associated with fewer GI adverse effects compared to the oral route.

Serum concentrations of granulocyte colony-stimulating factor (G-CSF) in antithyroid drug-induced agranulocytosis

Granulocyte colony-stimulating factor (G-CSF) levels in serum were determined by a highly-sensitive chemiluminescent enzyme immunoassay (limit of detection, 0.5 pg/ml) in 54 patients with Graves' disease including 6 patients complicated with methimazole-induced agranulocytosis. Serum G-CSF levels in patients with Graves' disease were not different from normal subjects and did not correlate with serum FT4 level or circulating neutrophil counts. Before the onset of agranulocytosis, there was no difference in serum G-CSF level between the patients complicated with agranulocytosis and the uncomplicated patients. When circulating neutrophil counts decreased to less than 0.5 x 10(9)/L, serum G-CSF level elevated with the mean of 106.8 +/- 82.2 (SD) pg/ml, but the level did not correlate with the duration of agranulocytosis. Interestingly, maximum serum G-CSF level during the treatment with recombinant human G-CSF (100 microg/day) was related to bone marrow finding at the onset of agranulocytosis and correlated with the duration of agranulocytosis (r = 0.824, p < 0.05). In conclusion, measuring serum G-CSF levels with a highly-sensitive chemiluminescent enzyme immunoassay revealed that 1) thyrotoxicosis does not affect serum G-CSF level, 2) serum G-CSF level during antithyroid drug treatment does not play an important role in development of agranulocytosis, 3) the maximum serum G-CSF level in the course of agranulocytosis is related to the responsiveness of bone marrow to G-CSF and the recovery time from agranulocytosis.

[Aplastic anaemia caused by thiamazole--a case report]

Antithyreoid drugs are known causative agents of agranulocytosis and, in rare cases, aplastic anaemia as well. This is a case report of a female patient with secondary aplastic anaemia developed two years after continual use of thiamazole. She suffered from exhaustion and massive epistaxis. Physical examination revealed pale skin and mucous membranes, skin hematomas (body and legs) and high body temperature--39 degrees C. At admission, her blood film revealed pancytopaenia with 75 g/l hemoglobin concentration, 1.0 x 10(9)/l leukocytes and severe thrombocytopaenia--7.0 x 10(9)/l. Differential count showed 91% of lymphocytes, 1% of monocytes and only 8% of neuthrophils. Bone marrow cytology and pathohistologic findings revealed severe hypocellularity, replaced with fat cells and only 10% of active hematopoietic tissue. In the acute phase of illness, in vitro growth of bone marrow progenitors was completely absent. Treatment was initiated with prednisone and danazol. During that time, she suffered from epistaxis, gastro-intestinal bleeding and herpes infection. Due to therapeutic failure cyclosporine A was added after 21 days. There upon, slow recovery ensued. After two months, she was discharged from hospital with stable blood film findings (HB 83 g/l, WBC 4.6 x 10(9)/l, and PLT 30.0 x 10(9)/l). She was forbidden thiamazole for her life time. After recovery from the acute phase of illness, in vitro haematopoietic precursor cells examination was repeated. The number of CFU-E colonies stimulated with 1 IU EPO was decreased in comparison with the control values. Upon adding 100 micro/l of thiamazole (5 mg/ml concentration e.g. 500 mg per culture), the growth of CFU-E was completely prevented, followed by marked cytotoxicity signs. The treatment including low doses (5 mg/ kg body weight daily) of cyclosporine A administration was continued on outpatient basis. After one year, blood film showed almost normal results with 120 g/l hemoglobin concentration, 4.3x10(9)/l leukocytes and mild thrombocytopaenia 72.0 x 10(9)/l. She was transfusion free.

Aplasia cutis congenita after methimazole exposure in utero

We describe a patient who was exposed to the antithyroid drug methimazole during the first 6 weeks of gestation and was born prematurely with scalp and skull defects associated with facial asymmetry. A review of the literature seems to support the hypothesis that methimazole is a potential teratogen. Although the risk of birth defects is low with clinically applied doses of the drug, it cannot be regarded as safe and should therefore be avoided in the treatment of pregnant women.

Assessing thyroid hormone status in a patient with thyroid disease and renal failure: from theory to practice

A 35-year-old Asian male, treated for hyperthyroidism, systemic lupus erythematosis, and uremia presented with low serum total thyroxine (T4) and normal serum thyrotropin (TSH) levels. He had been receiving prednisone and methimazole for 15 weeks. Free T4 measured by direct equilibrium dialysis was in the hypothyroid range (0.3 ng/dL; normal, 0.8-2.7). Two possibilities were considered: (1) a weakly bound dialyzable inhibitor in uremic serum that interfered with this serum free T4 determination or (2) hypothyroidism with persistent TSH suppression because of prior hyperthyroidism. To determine whether a weakly bound inhibitor was involved, the patient's serum was serially diluted using two diluents: (1) an ultrafiltrate of the patient's serum, which would contain any unbound inhibitor, as well as free T4 and (2) an inert diluent. Free T4 measurements were similar with both, providing evidence against the presence of a dialyzable and ultrafilterable inhibitor. In conclusion, this patient was hypothyroid because of antithyroid drug administration, associated with prolonged central TSH suppression from preexisting hyperthyroidism. Discontinuation of methimazole resulted in normalization of serum total T4 and TSH values. Thus, paired, serial serum dilutions, using two different diluents, provided evidence for differentiation of appropriately low free T4 measurements (because of hypothyroidism), from spuriously low free T4 measurements (because of an interfering inhibitor).

Methimazole-induced aplastic anemia caused by hypocellular bone marrow with plasmacytosis

Aplastic anemia is a rare but severe complication of methimazole (MMI) treatment for Graves' disease. We present a case of a 53-year-old Japanese female who had been treated with 30 mg/d of MMI for 30 days for Graves' disease and was subsequently admitted to the Japan Self Defense Forces (JSDF) Central Hospital with a mild sore throat and high-grade fever that began the previous day. The patient had a reduced white blood cell count (WBC) count of 0.9 x 10(3) per microliter with severe granulocytopenia and increased lymphocytes, a platelet count of 49 x 10(3) per microliter, and hemoglobin of 10.6 g/dL. Bone marrow (BM) aspirates showed hypocellular bone marrow with plasmacytosis. Because of poor recovery of her peripheral blood values after withdrawal of MMI, she was given transfusions of platelets and erythrocytes thereafter. This is the second report of plasmacytosis in bone marrow of MMI-induced aplastic anemia, and suggests that immunogenic mechanisms may cause this rare complication.

Methimazole-induced Cholestatic Jaundice

Methimazole is a widely used and generally well-tolerated antithyroid agent. A 43-year-old woman had severe jaundice and itching 1 month after receiving methimazole (10 mg tid) and propranolol (20 mg tid) for treatment of hyperthyroidism. The patient continued treatment for another 4 days after the appearance of jaundice until she finished both medications. When seen at the emergency department 2 weeks later, she still had severe icterus, pruritus, and hyperbilirubinemia, formed mainly of the conjugated fraction. Methimazole-induced cholestasis was diagnosed, and propranolol therapy was resumed. Over the following 9 days, the symptoms improved and plasma bilirubin levels were normal after 12 weeks without methimazole. In rare cases within the first few weeks of therapy, this drug can cause severe and reversible cholestatic jaundice. Physicians and patients should be aware of this adverse effect so that, upon occurrence, they can discontinue methimazole therapy and avoid unnecessary invasive procedures.

Choanal atresia associated with prenatal methimazole exposure: Three new patients

We report three patients with bilateral choanal atresia in children prenatally exposed to methimazole (MMI) in order to define a MMI embryopathy clinical pattern. The combination of choanal atresia and other specific malformations strongly resembles previously reported patients exposed to MMI in utero. At present, propylthiouracil is considered the best treatment in pregnancies. However in Argentina and some other countries MMI is the only antithyroid drug, possibly posing a significant risk to the unborn fetus.

Intellectual development and thyroid function in children who were breast-fed by thyrotoxic mothers taking methimazole

OBJECTIVE

Recent studies have shown normal thyroid function in infants whose mothers receive methimazole (MMI) during breast-feeding. This study evaluates the long-term effect of MMI on thyroid function and intellectual development of such children.

DESIGN AND METHODS

Eighty-two children aged between 48 and 86 months were studied. Forty-two children had been breast-fed while their thyrotoxic lactating mothers received daily doses of MMI 20-30 mg in the first, 10 mg in the second and 5-10 mg for additional 10 months of therapy. Thyroid function of infants remained normal during the one year of MMI therapy of their mothers. Forty other infants served as controls. Serum T4, T3, and TSH concentrations, urinary iodine, thyroid antibodies, intelligence quotient (IQ), verbal and functional (performance) components (Wechsler and Goodenough tests) were measured in all children of the two groups.

RESULTS

Height, weight, serum T4, T3, TSH and antithyroid antibody titers were not different between children in the two groups. The mean IQ was 107 +/- 17 vs 106 +/- 16 (Goodenough test) and 103 +/- 10 vs 103 +/- 16 (Wechsler test) for children of thyrotoxic mothers and control children, respectively. There was no difference in verbal and functional IQ and their components between children of thyrotoxic MMI treated mothers and control children.

CONCLUSION

Thyroid function and physical and intellectual development of breast-fed infants whose thyrotoxic lactating mothers were treated with 20-30 mg doses of MMI daily are normal at age 48 to 86 months.

Methimazole-induced lupus erythematosus: a case report

A 15-year-old girl had a history of diffuse goiter and received methimazole treatment 2 months before admission to the hospital. She developed bilateral lower leg edema 5 days before admission and the laboratory examinations revealed leukopenia, anemia, proteinuria, and granular cast. Positive antinuclear antibodies and anti-double strand (anti-ds) DNA antibodies were noted, although complement levels were not reduced. Myeloperoxidase antineutrophil cytoplasmic antibody was positive. A renal biopsy disclosed that there was focal segmental glomerulosclerosis. Methimazole was discontinued, and she was treated with prednisolone and Plaquenil, after which the symptoms and laboratory tests became normal within 40 days. The prednisolone was discontinued after treatment for seven months. Currently, the anti-dsDNA, C3, C4, CBC, urinalysis, and thyroid function tests are within normal limits. With hydroxychloroquine and levothyroxine, she was free of symptoms after discontinuation of methimazole until now (about 21 months).

[Antithyroid agents and embryopathies]

First cause of hyperthyroidism among women of childbearing age, Graves' disease raises the risk of maternal and fetal complications, including eclampsia, cardiac failure, abortion, prematurity, fetal death, all of which can be avoided if maternal hyperthyroidism is closely controlled. The risk of transplacental hyperthyroidism has been shown to correlate to the titre of anti-TSH receptor antibodies and has to be evaluated not only in women treated for Graves' disease during pregnancy, but also in women who have previously received radio iodine treatment or undergone surgery for Graves' disease: TSH-receptor antibodies may indeed remain at a high level several years after initial treatment. Both methimazole and propylthiouracil are equally effective to restore maternal euthyroidism. Accumulation of case-reports relating congenital malformations (mostly aplasia cutis, but in some cases, severe malformations) among the offspring of methimazole-treated women suggests the possibility of a teratogenic effect of methimazole. Despite the fact that the link between severe congenital defects and methimazole exposure during pregnancy is not formally established, propylthiouracil should be preferred to methimazole for the treatment of young hyperthyroid women.

Neutropenic colitis with cecal perforation during antithyroid therapy

Neutropenic colitis, characterized by neutropenia plus cecal and ascending colon inflammation, is a rare complication of chemotherapy in hematological malignancies and, less commonly, of medication used to treat other diseases (e.g., hyperthyroidism). We report a case of neutropenic colitis with cecal perforation in a 44-year-old woman treated with methimazole for hyperthyroidism. The patient had received subtotal thyroidectomy for hyperthyroidism in 1984 and recurrent hyperthyroidism was found in 1993. She was then treated with methimazole for almost 3 months, when sustained fever, diarrhea, weakness, and progressive abdominal pain developed. Due to the findings of peritonitis and neutropenia, she underwent emergent laparotomy. During the operation, chronic ulceration of the cecum with perforation was found and resection of the ileocecal segment and ileostomy were performed. Three months later, closure of the ileostomy with anastomosis of the ileocolostomy was performed. Her condition was stable during 9 years' follow-up. In conclusion, neutropenic enterocolitis has a broad spectrum of clinical presentations that require alertness in patients with neutropenia. When detected late, it may lead to bowel perforation and even mortality.

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.

Thyroid function in breast-fed infants is not affected by methimazole-induced maternal hypothyroidism: results of a retrospective study

For many years, breast-feeding was forbidden if methimazole (MMI) was being used. However, a few studies have demonstrated the relative safety of MMI. The purpose of this study was to evaluate thyroid function of breast-fed infants whose lactating mothers became hypothyroid while taking methimazole. Between 1990 and 2001, 134 thyrotoxic lactating mothers received MMI while breast-feeding. MMI therapy was initiated between 2-8 months postpartum, 10-30 mg for the first month and 5-10 mg from the second until the twelfth month. In 16 mothers, TSH was increased at the end of one month of MMI therapy (Group 1). Infants of 18 mothers whose serum TSH was normal at the end of the first month were included as controls (Group 2). Mothers and their infants were clinically evaluated and serum T4, T3 and TSH were measured before and at 1, 2, 4, 8 and 12 months after MMI therapy. Serum MMI was measured in 8 infants 2 h after breast-feeding. Mean +/- SD of FT4I and FT3I were not statistically different between the two groups of mothers before MMI therapy. In all 34 mothers thyroid indices decreased one month after MMI therapy; FT4I: Group 1 from 19.8 +/- 4.3 to 6.0 +/- 4.8 (p<0.001) and Group 2 from 20.3 +/- 4.7 to 11.4 +/- 4.1 (p<0.001); FT3I: Group 1 from 602 +/- 56 to 146 +/- 52 (p<0.001) and Group 2 from 562 +/- 42 to 186 +/- 39 (p<0.001). The difference in FT4I, FT3I and TSH (20 +/- 18 vs 2.1 +/- 1.1 mU/l, p<0.001) between the 2 groups was significant at the end of the first month of MMI therapy. There was no significant difference in thyroid function of infants of these two groups one month after MMI therapy and all tests remained within the normal range during 12 months of treatment of their lactating mothers. Serum MMI levels were less than 0.03 in 6 and 0.03 and 0.035 microg/ml in the other 2 infants. The results further indicate the safety of MMI therapy in breast-feeding thyrotoxic women.

Diagnosis and management of Graves' disease

Graves' disease is characterized by hyperthyroidism, diffuse goitre, ophthalmopathy and, rarely, dermopathy. Although diagnostic testing is straightforward once Graves' disease is suspected, physicians need to be aware of heterogeneous and even atypical presentations of the disease, particularly in elderly patients. Because morbidity may be associated with even subtle forms of hyperthyroidism, treatment promoting long-term euthyroidism is necessary. Although all of the available treatments are effective, compliance is best assured by a full discussion of the risks and benefits of each approach. This review focuses on issues of diagnosis and management that will allow the primary care physician to identify patients with Graves' disease and guide them to recovery.

Gastrointestinal malformations in two infants born to women with hyperthyroidism untreated in the first trimester

We report two infants with gastrointestinal anomalies: one with esophageal atresia and tracheo-esophageal fistula and the other with biliary tree atresia, born to hyperthyroid women diagnosed and treated with methimazole after 14 weeks' gestation. Euthyroidism was documented in both infants. These cases raise the issue of whether untreated hyperthyroidism and not methimazole intake is the teratogen.

A successful pregnancy and delivery case of Graves' disease with myeloperoxidase antineutrophil cytoplasmic antibody induced by propylthiouracil

A 30-year-old female patient, diagnosed as having Graves' disease in 1996, was treated with propylthiouracil (PTU) for 4 years. She developed a low-grade fever from December 1999. As myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) vasculitis is one of the adverse effects of PTU, we examined serum MPO-ANCA level and found it was positive, but cytoplasmic-ANCA (c-ANCA) was negative. There were no symptoms that indicated other diseases associated with MPO-ANCA. She was confirmed to be at 6 weeks gestation, and thyroid hormone levels were elevated at that time. We discontinued PTU and gave methyl-mercaptoimidazole (MMI), and the titer of MPO-ANCA fell along with fever. Therefore we estimated the case as probable MPO-ANCA positive vasculitis induced by PTU. MMI was also suspended because of the development of hepatic dysfunction. After thyroid function was normalized by administration of potassium iodide, she underwent subtotal thyroidectomy, and delivered a 2350 g infant at 38 weeks' gestation, which was less than the normal birth weight of 2400 g. MPO-ANCA is considered to be one reason of low birth weight infant including hyperthyroidism. It is necessary to consider the appearance of the possibility of MPO-ANCA positive vasculitis in patients who are treated with PTU.

Drug-induced and postnatal hypothyroidism impairs the accumulation of diacylglycerol in liver and liver cell plasma membranes

BACKGROUND

Thyroid hormones are well known modulators of signal transduction. The effect of hyper- and hypo-thyroidism on diacylglycerol/protein kinase C (DAG/PKC) signaling in cardiomiocytes has been determined. Triiodothyronine (T3) has been shown to prevent the alpha1-adrenoreceptor-mediated activation of PKC but does not alter the stimulation of enzyme and hepatic metabolism by phorbol ethers. It has been suggested that the elevation of endogenous DAG in senescent or hypothyroid cells changes the PKC-dependent response of cells to phorbol esters and hormones. In the present study, was examined the formation of DAG and activation of PKC in liver cells from rats of different thyroid status.

RESULTS

The results obtained provide the first demonstration of DAG accumulation in liver and cell plasma membranes at age- and drug-dependent thyroid gland malfunction. The experiments were performed in either the [14C]CH3COOH-labeled rat liver, liver slices or hepatocytes labeled by [14C] oleic acid and [3H]arachidonic acid or [14C]palmitic acid as well as in the isolated liver cell plasma membranes of 90- and 720-day-old rats of different thyroid status. The decrease of T4 and T3 levels in blood serum of 720-day-old rats and mercazolil-treated animals was associated with increases of both the DAG mass in liver and liver cell plasma membranes and newly synthesized [14C]DAG level in liver and isolated hepatocytes. Hypothyroidism decreased PKC activity in both membrane and cytosol as well as phospholipid and triacylglycerol synthesis in liver. These hypothyroidism effects were restored in liver by injection of T4. T4 administration to the intact animals of different ages decreased the DAG level in liver and isolated plasma membranes and the content of newly synthesized DAG in liver. The reduction of DAG level in liver was not associated with increasing free fatty acid level. DAG labeling ratio 14C/3H in liver slices of rats of different thyroid state sharply differed from PL. DAG was relatively enriched in [14C]oleic acid whereas PL were enriched in [3H]arachidonic acid.

CONCLUSIONS

The above data have indicated that thyroid hormones are important physiological modulators of DAG level in rat liver and cell plasma membranes. Age- and drug-induced malfunction of thyroid gland resulted in a prominent decrease of glycerolipid synthesis which may promote DAG accumulation in liver.

Thyroid function and intellectual development of children of mothers taking methimazole during pregnancy

There is some debate regarding the safety of methimazole (MMI) therapy during pregnancy. It is not known whether MMI therapy in mothers during pregnancy is safe for their children or if it causes alterations in thyroid function and intellectual development during childhood. Twenty-three children, whose mothers were hyperthyroid during pregnancy and treated with MMI 5-20 mg were studied from age 3-11 yr. Thyroid function and liver function tests, urinary iodine, anti-thyroid antibodies, intelligence quotient (IQ), verbal and functional components of Wechsler test were performed on 23 children of thyrotoxic mothers and 30 controls. In all children T3, T4, RT3U and TSH concentrations were normal. Mean T3, T4 and TSH values were 147 ng/dl, 9.7 microg/dl and 1.2 mU/l, respectively. Height, weight, thyroid function, and thyroid antibodies did not differ from controls. None of the children had T4 below 6 microg/dl or TSH>3.0 mU/l. Liver enzymes and serum albumin were normal in both groups. Mann-Whitney test showed no difference in verbal and performance IQ and their components between children of thyrotoxic mothers and controls. Total IQ of cases and controls was 117 +/- 11 and 113 +/- 14, respectively. No deleterious effect occurred in thyroid function and physical and intellectual development of children whose mothers were treated during pregnancy with doses of MMI up to 20 mg daily.

Remission of Graves' hyperthyroidism treated with methimazole

BACKGROUND

Long-term thionamide treatment is considered one of the main resources for Graves' hyperthyroidism. Although a 54.2% remission rate in patients so treated in Mexico was previously reported, most articles have shown a wide variation over time. In the present article we report the actual remission rate of long-term methimazole (MMZ) therapy of Graves' hyperthyroidism in Mexico.

METHODS

We carried out a retrospective study of long-term MMZ treatment in 80 patients with Graves' hyperthyroidism with a postreatment follow-up of at least twelve months. Remission was considered by clinical as well as biochemical criteria.

RESULTS

We studied 63 females and 17 males, mean age 37.7 +/- 10.4 years. Duration of symptoms was 13.3 +/- 20.7 months. Daily MMZ dose: 20.0 +/- 8.8 mg, treatment duration 16.7 +/- 8.9 months and follow-up was 34.8 +/- 60.3 months. Fourteen patients (17.5%) are in remission and sixty six relapsed (82.5%). Relapse occurred after a mean of an 11.9 +/- 11.8 month follow-up. Goiter size was the only statistically significant remission sign whereas age, disease duration, MMZ dose, exophthalmos, treatment duration or 1-thyroxine concomitant use were not useful predictive factors.

CONCLUSIONS

Remission rate of long-term MMZ treatment of Graves' hyperthyroidism has substantially decreased in Mexico, since the previous report. We suggest that our results may be related to an increase of iodine intake or poor treatment, compliance. Goiter size was the only remission predictive sign. Due to our low remission rate we suggest Graves' disease patients must be selected for this kind of treatment.

Effect of antioxidants (vitamin C, E and turmeric extract) on methimazole induced hypothyroidism in rats

The study was to investigate the protective effect of antioxidants against methimazole (MMI) induced hypothyroidism in rats. Male Wistar rats were fed MMI, MMI plus vitamin C, MMI plus vitamin E and MMI plus turmeric extract (TE) supplemented diet. At the end of the experiments, thyroid weights, thyroxine (T4), triiodothyronine (T3) and cholesterol levels were determined. It was observed that MMI treated rats showed increase in thyroid weights, very low levels of circulating T4, T3 and increased levels of total cholesterol as compared to controls (P< 0.001). However, rats which received Vit. C, Vit. E or TE along with MMI showed reduced weights (38-55% less) in thyroid glands (P < 0.01), less suppressed T4 and T3 levels (2-6% and 7-35% respectively) and less increase in total cholesterol levels (19-52%) which are statistically significant. The data suggest the positive effect of antioxidants on thyroid gland which could be due to direct involvement of antioxidants on thyroid gland.

Thyroid function in breast-fed infants whose mothers take high doses of methimazole

Recently, a few studies have shown the safety of methimazole (MMI) therapy of thyrotoxic lactating mothers on thyroid function of their infants. However, it is not known whether the effect of moderately high doses of MMI therapy on lactating mothers can be dangerous for breast-fed infants. Eighty-eight thyrotoxic lactating mothers and their infants were studied. 46 received 20 mg MMI and 42 were given 30 mg MMI during the first month, 10 mg for the second and 5-10 mg for additional 10 months of therapy. Serum T4, T3 and TSH concentrations and in hyperthyroid MMI treated mothers and their RT3U were measured in hyperthyroid MMI treated mothers and their infants, before and at 1, 2, 6, and 12 months after initiation of therapy. Serum MMI was measured in the infants of thyrotoxic mothers taking 20-30 mg MMI. Mean+/-SD of free T4 index (FT4I) in thyrotoxic mothers treated with 20 and 30 mg MMI for one month decreased from 20.1+/-4.2 to 9.7+/-1.5 (p<0.001) and from 20.6+/-4.8 to 8.6+/-3.0 (p<0.001), respectively. Values for free T3 index (FT3I) decreased from 587+/-53 to 180+/-39 (p<0.001) and from 610+/-49 to 151+/-31 (p<0.001) in those treated with 20 and 30 mg MMI, respectively. By the end of one month 5 had elevated FT4I or FT3I or both and 12 had elevated TSH. The dose of MMI was adjusted and thyroid function remained normal up to 12 months of MMI therapy in thyrotoxic lactating mothers. Serum T4, T3 and TSH concentrations of breast-fed infants were normal before and up to 12 months of MMI therapy of their breast-feeding mothers. The lowest T4 and T3 and the highest TSH values were 101 nmol/l, 1.8 nmol/l and 4.1 mU/l, respectively. Serum MMI levels were <0.03 in 7 and 0.03, 0.034 and 0.035 microg/ml in the other 3 infants. We conclude that the treatment of hyperthyroid lactating mothers with doses of 20-30 mg MMI day does not cause deleterious effects on thyroid function of their breast-fed infants.

Methimazole-induced hepatotoxicity

OBJECTIVE

To present the case of a patient with Graves' hyperthyroidism in whom treatment with methimazole led to severe cholestasis.

METHODS

A detailed case report and an overview of previously published cases of methimazole- and carbimazole-induced hepatotoxicity, found in a MEDLINE search with use of methimazole, carbimazole, thionamides and antithyroid agents as subject headings, are provided.

RESULTS

In a 36-year-old woman with severe hyperthyroidism, treatment with methimazole (20 mg twice daily) was initiated. Nineteen days later, pruritus, scleral icterus, dark urine, and abdominal discomfort prompted discontinuation of the therapy. Laboratory investigations and abdominal ultrasonography showed findings consistent with a cholestatic reaction to methimazole. Recovery was slow but complete. Of the 30 previously published cases of hepatotoxicity related to treatment with methimazole or carbimazole in which the nature of the hepatic injury was described, 19 were also cholestatic.

CONCLUSION

Physicians should be aware that thionamide drugs can be associated with hepatotoxicity. Analysis of the known cases suggests that older age of the patient and higher dose of the drug are risk factors for cholestatic injury.

An autosomal recessive syndrome of choanal atresia, hypothelia/athelia and thyroid gland anomalies overlapping bamforth syndrome, ANOTHER syndrome and methimazole embryopathy

Two sibs from an inbred Arab family are described with an autosomal syndrome of choanal atresia, hypothelia/athelia and thyroid gland anomalies overlapping Bamforth syndrome, ANOTHER syndrome and methimazole embryopathy. In one case the syndrome described was lethal. Cases with similar features are reviewed and genetic mutations discussed.

Extrathyroidal actions of antithyroid thionamides

Some compounds having thionamide structure inhibit thyroid functions. Such antithyroid thionamides include mercaptomethylimidazole (methimazole), thiourea and propylthiouracil, of which mercaptomethylimidazole is widely used to treat hyperthyroidism. Undesirable side effects develop from these drugs due to extrathyroidal actions. Antithyroid thionamides inhibit lactoperoxidase which contributes to the antibacterial activities of a number of mammalian exocrine gland secretions that protect a variety of mucosal surfaces. These drugs stimulate both gastric acid and pepsinogen secretions, thereby augmenting the severity of gastric ulcers and preventing wound healing. Increased gastric acid secretion is partially due to the H2 receptor activation, and also through the stimulation of the parietal cell by intracellular generation of H2O2 following inactivation of the gastric peroxidase-catalase system. Severe abnormalities may develop in blood cells and the immune system after thionamide therapy. It causes agranulocytosis, aplastic anemia, and purpura along with immune suppression. Olfactory and auditory systems are also affected by these drugs. Thionamide affects the sense of smell and taste and also causes loss of hearing. It binds to the Bowman's glands in the olfactory mucosa and causes extensive lesion in the olfactory mucosa. Thionamides also affect gene expression and modulate the functions of some cell types. A brief account of the chemistry and metabolism of antithyroid thionamides, along with their biological actions are presented.

High dose of (131)I therapy for the treatment of hyperthyroidism caused by Graves' disease

Radioactive iodine ((131)I) has become the most widely used therapy for patients with hyperthyroidism caused by Graves' disease in the United States. There remains, however, significant variability among (131)I dosing regimens, and it is clear that most patients ultimately develop hypothyroidism after therapy. To avoid persistent hyperthyroidism, we adopted a high dose (131)I therapy protocol based on measurement of 24-h thyroid (123)I uptake designed to deliver 8 mCi (296 MBq) to the thyroid gland 24 h after (131)I administration. To evaluate the efficacy of this protocol, we reviewed our clinical experience over a 7-yr period. We treated 261 patients (219 women and 42 men) with hyperthyroidism caused by Graves' disease with (131)I [mean dose, 14.6 mCi (540 MBq)] between 1993 and 1999. Before treatment, 207 (79%) had received an antithyroid drug (109 propylthiouracil and 98 methimazole). We determined their thyroid status 1 yr after treatment in relation to age, pretreatment with an antithyroid drug, pretreatment thyroid size, and dose of (131)I retained in the thyroid 24 h after treatment. Among the 261 patients, 225 (86%) were euthyroid or hypothyroid 1 yr after treatment, and 36 patients (14%) had persistent hyperthyroidism and required a second treatment. The patients who had persistent hyperthyroidism were younger (P < 0.01), had larger thyroid glands (P < 0.01), higher pretreatment thyroid (123)I uptake values (P < 0.01), and higher serum T(4) concentrations (P < 0.01) and were more likely to have taken antithyroid medication before administration of (131)I (P = 0.01). Five of these patients developed transient hypothyroidism, followed by thyrotoxicosis. There was an asymptotic, inverse relationship between the retained dose of (131)I at 24 h and persistent hyperthyroidism, revealing a 5-10% failure rate despite delivery of up to 400 microCi (14.8 MBq)/g. A dose of (131)I that results in accumulation of 8 mCi (296 MBq) in the thyroid gland 24 h after administration is an effective treatment for the majority of patients with Graves' hyperthyroidism. Young patients with larger thyroid glands, higher serum T(4) concentrations, and higher 24-h thyroid (123)I uptake values, and those pretreated with antithyroid medication for greater than 4 months are at higher risk for treatment failure. A higher dose of (131)I may be advisable in such patients.

Retrospective analysis of 18 cases of antithyroid drug (ATD)-induced agranulocytosis

In this study, we retrospectively analyzed 18 patients in whom antithyroid drug (ATD)-induced agranulocytosis developed during treatment of Graves' disease. All patients were more than 20 years of age, and we saw no correlation between age and the development of agranulocytosis. In 17 of 18 patients, ATD-induced agranulocytosis developed within 2 to 12 weeks of starting ATD treatment. Development of agranulocytosis was related to the dose of ATD. In some patients, agranulocytosis developed abruptly, and even weekly routine WBC and granulocyte counts failed to predict all case occurrences. Fever and sore throat were the earliest symptoms of agranulocytosis; patients who developed either of these symptoms were closely monitored immediately with WBC and granulocyte count examinations. In this series of patients, treatment with granulocyte-macrophage colony stimulating factor (GM-CSF) increased the granulocyte counts, whereas the effectiveness of glucocorticoid treatment was not confirmed.