Thyrotoxicosis in prepubertal children compared with pubertal and postpubertal patients

Toxicological considerations for antithyroid drugs in children

INTRODUCTION

Propylthiouracil (PTU), methimazole (MMI) and carbimazole are indicated for the treatment of hyperthyroidism in adult and pediatric patients. The aim of this review is to present all the relevant information regarding the use of antithyroid drugs (ATD) in pediatric thyrotoxic cases, the pediatric toxicology of ATD and the warning which has recently been issued for PTU by the FDA.

AREAS COVERED

Epidemiology, diagnosis and treatment of pediatric thyrotoxicosis are all presented in this article. The authors also extensively discuss the details regarding the pharmacology, bioactivation, biodisposition, bioavailability and pharmacokinetic properties of the two main ATD (MMI and PTU).

EXPERT OPINION

The FDA recently reported that use of PTU is associated with a higher risk for clinically serious or fatal liver injury compared to MMI in both adult and pediatric patients. They also found that congenital malformations were reported approximately three times more often with prenatal exposure to MMI compared with PTU and especially with the use of MMI during the first trimester of pregnancy. The authors believe that PTU should not be used in pediatric patients unless the patient is allergic to or intolerant of MMI, and there are no other treatment options available. That being said, PTU may be the treatment of choice during, and just before, the first trimester of pregnancy.

Serendipitous identification of Graves' disease in identical twins with polydipsia

Graves' disease in adolescents and adults usually presents with classic symptoms including weight loss, frequent stools, irritability, and heat intolerance. However, the clinical manifestations of hyperthyroidism in young children are often subtle, unrecognized, and atypical. Here, we report a 6 year-old girl who presented for evaluation of increased. thirst. Review of systems was negative with respect to weight loss, irritability, palpitations, diarrhea, and school performance problems. Physical exam was unremarkable except for an enlarged thyroid gland. Her identical twin sister, who incidentally accompanied her to clinic, also had a previously unidentified goiter. Testing for diabetes was negative. Further laboratory investigation was consistent with Graves' disease in both girls. Polydipsia is a rare and unusual presenting feature of hyperthyroidism in children. The evolution of this case highlights the importance of maintaining a high index of suspicion for thyroid disease during childhood.

Adverse events associated with methimazole therapy of graves' disease in children

Objective. Graves' disease is the most common cause of hyperthyroidism in the pediatric population. Antithyroid medications used in children and adults include propylthiouracil (PTU) and methimazole (MMI). At our center we have routinely used MMI for Graves' disease therapy. Our goals are to provide insights into adverse events that can be associated with MMI use. Methods. We reviewed the adverse events associated with MMI use in our last one hundred consecutive pediatric patients treated with this medication. Results. The range in the patient age was 3.5 to 18 years. The patients were treated with an average daily dose of MMI of 0.3+/-0.2 mg/kg/day. Adverse events attributed to the use of the medication were seen in 19 patients at 17+/-7 weeks of therapy. The most common side effects included pruritus and hives, which were seen in 8 patients. Three patients developed diffuse arthralgia and joint pain. Two patients developed neutropenia. Three patients developed Stevens-Johnson syndrome, requiring hospitalization in 1 child. Cholestatic jaundice was observed in 1 patient. No specific risk-factors for the development of adverse events were identified. Conclusions. MMI use in children is associated with a low but real risk of minor and major side effects.

Radioactive iodine for hyperthyroidism in children and adolescents: referral rate and response to treatment

OBJECTIVES

Radioactive iodine ((131)I) therapy is increasingly viewed as a safe and effective treatment for paediatric and adolescent hyperthyroidism. Our objective was to estimate treatment response and its predictors and describe current referral practices for (131)I therapy.

DESIGN

Retrospective study.

PATIENTS

One hundred and thirty-one children 30 days-21 years old with laboratory evidence of hyperthyroidism, seen in an academic paediatric and adolescent endocrinology practice.

MEASUREMENTS

Rate of referral, indications for (131)I, predictors of poor treatment response.

RESULTS

Thirty-eight of 102 patients with persistent hyperthyroidism (37%) received (131)I (160 μCi/g thyroid tissue/(131)I uptake), as did an additional 10 patients initially evaluated by adult thyroidologists. Primary indications were intolerance to (29%) or poor control on (19%) antithyroid drugs, patient preference (50%) and unknown (2%). Of 48 patients treated with (131)I, 89% and 11% became hypothyroid after one and two (131)I doses, respectively. The goal of (131)I therapy was attainment of hypothyroidism. 'Poor treatment response' (seen in 27%) was defined as requirement for a second (131)I dose or failure to achieve hypothyroidism after 6 months. Predictors of poor treatment response included: previous use of antithyroid drugs (37%vs. 0%, P = 0.02), ophthalmopathy (58%vs. 8%, P = 0.002), and an interval of ≥ 12 months from diagnosis to (131)I (50%vs. 10%, P = 0.003). A very elevated free T4 tended to be more prevalent in those with poor response.

CONCLUSIONS

In children and adolescents with hyperthyroidism, high rates of success after (131)I are achievable. Use of antithyroid drugs, pre-existing eye disease and prolonged time to (131)I may confer relative resistance to (131)I.

Radioiodine treatment for pediatric hyperthyroid Grave's disease

Grave's disease (GD) is an autoimmune disease in which excessive amounts of thyroid hormones circulate in the blood. Treatment for pediatric GD includes (1) antithyroid drugs (ATD), (2) radioiodine, and (3) thyroidectomy. Yet, the optimal therapy remains controversial. We collected studies from all electronically available sources as well as from conferences held in China. All studies using radioiodine and/or ATD and/or thyroidectomy were included. Information was found on 1,874 pediatric GD patients treated with radioiodine, 1,279 patients treated with ATD and 1,362 patients treated surgically. The cure rate for radioiodine was 49.8%; the incidence of hypothyroidism, 37.8%; of relapse, 6.3%; of adverse effects, 1.55%; and of drop outs, 0.6%. These data show that radioiodine treatment is safe and effective in pediatric GD with significant lower incidence of relapse and adverse effects but significantly higher incidence of hypothyroidism as compared with both ATD and thyroidectomy. For the time being, radioiodine treatment for pediatric GD remains an excellent first-line therapy and a good second-line therapy for patients with ATD failure, severe complications, or poor compliance.

Propylthiouracil (PTU) Hepatoxicity in Children and Recommendations for Discontinuation of Use

Propylthiouracil (PTU) was introduced for clinical use in July 1947 for Graves' disease (GD) treatment. Over the 60 years that this medication has been used, reports of PTU-related liver failure and death have accumulated. On October 28, 2008, an expert panel evaluated PTU drug safety in children at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) It is estimated that about 4000 pediatric patients per year with GD are being treated with antithyroid drugs (ATDs) in the United States, and up to 30% of pediatric patients with GD are being treated with PTU. The risk of severe PTU-induced liver failure is estimated as 1 in 2000-4000 children. The number of children developing reversible PTU-induced liver injury is estimated to be at least 1 in 200. Routine biochemical surveillance of liver function and hepatocellular integrity is not useful in identifying children who will develop liver failure. Children appear to be at higher risk for PTU-induced liver injury than adults. PTU should not be used as first line therapy for the treatment of GD in children. Current PTU use in children taking this medication should be stopped in favor of alternate therapies.

Radioiodine treatment for pediatric Graves' disease

BACKGROUND

Pediatric Graves' disease (GD) is an autoimmune disease in which excessive amounts of thyroid hormones circulate in the blood. Treatments for pediatric GD include antithyroid drugs (ATD), thyroidectomy and radioiodine. Up to date, the optimal therapy remains controversial.

OBJECTIVES

To assess the effects of radioiodine treatment for pediatric GD.

SEARCH STRATEGY

Studies were obtained from computerized searches of MEDLINE, EMBASE, The Cochrane Library, China National Infrastructure (CNKI) and paper collections of conferences held in Chinese.

SELECTION CRITERIA

Randomised controlled trials, controlled clinical trials and prospective cohort studies comparing the effects of radioiodine with ATD or thyroidectomy with a duration of follow-up at least one year.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality, extracted data and interviewed authors of all potentially relevant studies by telephone or electronic mail to verify randomization procedures. One author entered data into a data extraction form and another author verified the results of this procedure.

MAIN RESULTS

Two prospective controlled clinical trials involving 167 patients were included. All of them were of low quality. Radioiodine treatment versus ATD showed benefits in achieving euthyroidism (relative risk (RR) 1.70, 95% confidence interval (CI) 1.29 to 2.24). Radioiodine treatment showed a higher incidence of hypothyroidism compared with ATD (RR 6.46, 95% CI 1.16 to 35.81). No significant differences in modifying Graves' opthalmopathy (worsening or appearance) between radioiodine treatment and ATD (RR 1.30, 95% CI 0.56 to 3.00) were observed. No trial evaluated mortality, health related quality of life, economic outcomes or compliance with treatments.

AUTHORS' CONCLUSIONS

The limited results in Chinese suggest that a gland specific lower dosage of radioiodine treatment is potentially effective for pediatric GD, but a significant higher incidence of hypothyroidism compared with ATD was observed. However, we could not identify a well-designed trial to provide strong evidence for radioiodine in the treatment of pediatric GD. High-quality randomised controlled clinical trials are needed to guide treatment choice.

Predicting the likelihood of remission in children with Graves' disease: a prospective, multicenter study

OBJECTIVE

The optimal treatment for Graves' disease in children is controversial. Antithyroid medications are often used initially, but many children eventually require alternative therapies. We evaluated predictors of remission after 2 years of antithyroid medication use.

METHODS

We prospectively studied children who had Graves' disease and were treated with antithyroid medications. We compared children who achieved remission after 2 years with those who had persistent disease to determine which variables were associated with remission; multiple logistic regression and binary recursive partitioning analyses were used to evaluate interactions among predictive variables.

RESULTS

Of 51 children who completed the study, 15 (29%) achieved remission. Children who achieved remission had lower thyroid hormone concentrations at presentation than those with persistent disease (free thyroxine: 6.17 +/- 3.10 vs 9.86 +/- 7.54 ng/dL; total triiodothyronine: 431 +/- 175 vs 561 +/- 225 ng/dL). Children who achieved remission were also more likely to be euthyroid within 3 months of initiating propylthiouracil (82% vs 29%). Binary recursive partitioning analysis identified rapid achievement of euthyroid status after initiation of propylthiouracil, lower initial triiodothyronine, and older age as significant predictors of remission. CONCLUSIONS; Thyroid hormone concentrations at diagnosis, age, and initial response to propylthiouracil can be used to stratify patients according to the likelihood of remission after 2 years of antithyroid medication use. These data provide a useful guide for clinical decision-making regarding Graves' disease in children.

Clinical and endocrine features and long-term outcome of Graves' disease in early childhood

Hyperthyroidism is rare in early childhood and most commonly caused by Graves' disease. We report 14 children (4 boys, 10 girls) aged 3.4-7.5 yr. At diagnosis, all patients had weight loss, hyperkinetic activity, tachycardia, difficulty sleeping, and poor concentration and 11 presented with proptosis. Four patients developed long-term neuropsychological problems. There was a family history in 7 cases. All patients had goiters, clinically assessed to be large and diffuse in 21%, medium-sized in 43%, and small in 36%. At diagnosis, height was increased with median (range) height; 1.25 standard deviation score (SDS) (-0.2-5.24) and body mass index (BMI) was decreased; -0.48 SDS (-1.65-1.26). Height and BMI SDS values were statistically different (p<0.032) Bone age was advanced in 4 of 5 children, who had assessments. Total or free T4 levels were elevated and TSH was undetectable. Ninety percent of patients (12/14) had positive thyroid peroxidase autoantibodies, mean level 680 IU/ml (range 50-1347). Initial treatment was with antithyroid medication using carbimazole; median dose 0.75 mg/kg/day (no.=13) or propylthiouracyl 15 mg/kg/day (no.=1). T4 was added in 6 patients. Normalisation of serum T4 occurred at 4 months (1- 9) and TSH at 7 months (3-24) after start of therapy. Treatment was discontinued after a minimum of 2 yr in 11 patients, relapse occurring in 9. Median duration of total therapy was 58 months (18-132). During adolescence, 4 patients had curative therapy by surgery (no.=2) or radioiodine (no.=2). In conclusion, disturbance of growth, behavioral difficulties and infrequent spontaneous remission are key features of Graves' disease in early childhood.

An optimal treatment for pediatric Graves' disease is radioiodine

CONTEXT

Antithyroid medications, surgery, and radioactive iodine have been used for more than five decades for the treatment of hyperthyroidism due to Graves' disease in children, adolescents, and adults. Despite the widespread use of these different approaches, controversy still exists relative to the merits of each treatment, especially regarding the use of radioactive iodine.

OBJECTIVE

The objective of the study was to address the risk and benefits of (131)I therapy, as compared with other treatment approaches. POSITION: Long-term, spontaneous remission of Graves' disease occurs in less than 30% of children. Thus, the majority of children with Graves' disease will need definitive, curative therapy. There is little evidence that use of antithyroid medications beyond 1 or 2 yr increases the likelihood of spontaneous, long-term remission. Although the use of antithyroid medications is standard practice, the use of antithyroid medications involves definite risks. When used at sufficient doses, radioactive iodine is an effective cure for Graves' disease and is associated with few acute side effects. Potential long-term adverse side effects, including thyroid cancer and genetic damage, have yet to be observed in individuals treated as children or adolescents with (131)I.

CONCLUSION

Properly administered, radioactive iodine remains an ideal form of treatment for Graves' disease in the pediatric population. Because of the increased risk of thyroid cancer associated with low-dose thyroid irradiation in children, larger, rather than smaller, doses of (131)I should be given.

Propylthiouracil-associated liver failure presenting as probable autoimmune hepatitis in a child with Graves' disease

This case describes a young girl with Graves' disease, who presented with fulminant hepatic failure 9 months into propylthiouracil (PTU) therapy. Her clinical presentation was consistent with 'probable autoimmune hepatitis,' as defined by the International Autoimmune Hepatitis Group scoring system. Despite discontinuation of PTU and high-dose steroid therapy, she required liver transplantation. Subsequent pathology could not definitively rule out autoimmune hepatitis. PTU is an important cause of drug-related liver failure in children, and clinicians should be mindful that it is frequently used in patients who already have an underlying risk of autoimmune liver disease.

Graves' disease in children and adolescents: response to long-term treatment

BACKGROUND

Optimal treatment of Graves' disease in paediatric patients is still a matter of controversy. Antithyroid drugs, radioiodine and thyroidectomy are the three therapeutic options available.

AIM

To report our experience of long-term medical treatment and outcome of paediatric Graves' disease.

METHODS

A 5-y-long medical protocol was implemented in 20 children and adolescents with Graves' disease. All patients received antithyroid drugs as the first therapeutic option; patients who did not enter long-term remission received I(131) and/or surgery as the definitive treatment.

RESULTS

The mean age at diagnosis was 12.1+/-4 y. Only two patients were males, both presenting concomitant type 1 diabetes. Mean follow-up was 13.8+/-5.5 y. Forty per cent of patients achieved long-term remission with low antithyroid drugs doses (mean treatment time: 5.4+/-1.4 y). Six patients received I(131) as definitive treatment and another six underwent surgery after completing medical treatment for 6.8+/-4.1 and 5.1+/-2 y, respectively. No patients requiring high antithyroid drugs doses to maintain euthyroidism reached long-term remission and needed I(131) and/or surgery.

CONCLUSION

Implementation of a long-term antithyroid drug protocol achieved 40% long-term remissions in paediatric patients with Graves' disease. Need for maintained high doses of antithyroid drugs could be considered a predictive factor for no remission. When permanent remission was not obtained by medical treatment, I(131)and/or surgery allowed healing in all cases.

Juvenile thyrotoxicosis; can we do better?

Thyrotoxicosis remains a frustrating condition for the young person, family, and health professionals involved. The associated symptoms do not always suggest thyroid disease and patients can be unwell for many months before the diagnosis is made. The antithyroid drug regimen used to treat children and adolescents with thyrotoxicosis varies from one unit to another and yet the potentially life threatening side effects and remission rates post-treatment may be related to the regimen used. Most patients with thyrotoxicosis will need many years of drug therapy if the thyroid gland is not removed surgically or destroyed by radioiodine. Even "definitive" treatment will typically necessitate thyroxine replacement for life.

[Graves' disease in children: management and review of 20 patients]

INTRODUCTION

Hyperthyroidism is a rare condition among children and the most common cause is Graves' disease. The best therapy for these patients continues to be debated.

PATIENTS AND METHODS

The medical records of 20 patients with Graves' hyperthyroidism who were treated between 1989 and 2003 were reviewed. Clinical symptoms, thyroid function, thyroid autoantibodies, thyroid imaging tests, first line therapy, disease or treatment-induced complications and the need for a secondary treatment option, as well as outcomes, were analyzed.

RESULTS

Age at diagnosis ranged from 5 to 16 years and there were more girls than boys (3:1). The most frequent symptom was hyperactivity (58 %). The most frequent sign was goiter (79 %). Thyroid-stimulating immunoglobulin antibodies were found in 90 % of the patients, at the beginning or during the course of the disease. All of the patients received antithyroid medication as first line therapy, but remission was achieved in just one patient. Surgical thyroidectomy was required in three patients, and two patients were treated with radioiodine.

CONCLUSION

Because few children achieve remission with medical therapy, other types of treatment (surgery or radioiodine) are often required. Although antithyroid drugs are considered the first choice for treatment in Europe, some authors advocate radioiodine as the treatment of choice.

Influence of iodine-131 dose on the outcome of hyperthyroidism in children

OBJECTIVES

Iodine-131 is an effective treatment for Graves' hyperthyroidism in children and adults. Yet the responses to treatment as related to iodine-131 dose in children are not well-defined. The objective of this study was to examine the relationship between the dose of iodine-131 in children with hyperthyroidism and thyroid status 1 year after treatment.

METHODS

We examined the outcome of iodine-131 treatment in children and adolescents with Graves' disease, as related to dose. Three iodine-131 doses were compared: 72 to 108 Gy (80-120 microCi/g), 180 to 225 Gy (200-250 microCi/g), and 270 to 364 Gy (300-405 microCi/g) in 31 patients ranging in age from 7 to 18 years old. Thyroid status was assessed >1 year after therapy.

RESULTS

We found that doses of 100 Gy (110 microCi/g), 200 Gy (220 microCi/g), and 300 Gy (330 microCi/g) resulted in hypothyroidism in 50%, 70%, and 95% of treated individuals, respectively. These data show that to insure ablation of thyroid tissue doses, >270 Gy (300 microCi/g) is needed, especially when the thyroid is large.