Thyrotoxicosis in childhood

The "slightly" abnormal thyroid test: What is the pediatrician to do?

Thyroid disorders are common in pediatrics. Tests of thyroid function are widely available and frequently ordered in the pediatric healthcare setting. This is sometimes driven by common signs or symptoms of thyroid disease. All too often, it is driven by patients and their parents requesting thyroid tests for nonspecific symptoms, such as fatigue, obesity or family history of thyroid disease. The decision to order thyroid tests, as well as which test(s) of thyroid function to order, deserves careful thought rather than a reflexive "thyroid panel" for every patient. Thyroid stimulating hormone (TSH) is the single most appropriate test of thyroid function when screening a pediatric or adolescent for thyroid disorders. Adding more tests only increases the likelihood that a minor (and often insignificant) abnormality will be found. These incidental abnormalities can create anxiety for the parent and child, and usually results in additional testing, referral to a pediatric endocrinologist, and further expense. This review will aim to guide the pediatric primary care provider on the choice of appropriate screening test(s) for acquired thyroid dysfunction in children and adolescents, as well as the proper interpretation of the test(s). Emphasis will be placed on the "slightly" abnormal thyroid screening test. Specific thyroid tests to be reviewed include TSH, (free) T4, (free) T3, and thyroid antibodies. Finally, this review will aim to guide decisions on follow-up, additional testing, and reasons for referral to a pediatric endocrinologist. Congenital hypothyroidism, including abnormalities on state newborn screening, will not be discussed.

Predictive factors for early response to methimazole in children and adolescents with Graves disease: a single-institute study between 1993 and 2013

PURPOSE

We aimed to investigate the predictive factors for early response to methimazole (MMI) in pediatric patients with Graves disease (GD).

METHODS

Our study included 44 pediatric patients who were diagnosed with GD between January 1, 1993, and December 31, 2013, and were available for follow-up, achieving a normalization of thyroid functions (TFs) at the Chonbuk National University Hospital Pediatric Department. We retrospectively analyzed TFs such as tri-iodothyronine (T3), free thyroxine (fT4), thyroid-stimulating hormone (TSH), and thyroid antibody levels at diagnosis. We also examined their family history of thyroid disease, symptoms at presentation, and normalization time for TF after treatment. We divided our clinical series of patients into the following 4 age groups: <7 years old, 7-12 years old, 13-15 years old, and 16-18 years old.

RESULTS

At diagnosis, the time of normalization of T3 was significantly shorter in the higher antimicrosomal antibody (AMA) group compared with the lower AMA group (2.53 months vs. 6.18 months) (P<0.05). However, the time of normalization of T3/fT4/TSH had no significant correlations with other variables such as age, sex, a family history of thyroid diseases, thyroglobulin, thyroid-stimulating immunoglobulin, or antithyroglobulin antibody (ATA).

CONCLUSION

Higher serological titers of AMA at diagnosis may have prognostic value in the response to initial MMI treatment in pediatric hyperthyroid GD patients.

Diagnostic approach to goitre in children

Thyroid disease is a common paediatric disorder that affects up to 3.7% of school-aged children, and it usually presents with a goitre. By far, the most frequent cause of a goitre is autoimmune thyroid disease, although a benign colloid goitre is also a common cause. The present review focuses on the diagnostic approach to a child with a hypothyroid, hyperthyroid or euthyroid goitre.

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.

Thyroid stimulating immunoglobulin is often negative in children with Graves' disease

BACKGROUND

The diagnosis of Graves' disease (GD) is typically confirmed with a thyroid stimulating immunoglobulin (TSI) titer. While TSI is reported to be positive in >90% of patients with GD, our anecdotal experience suggests that TSI negative GD may be more common in children.

AIM

To investigate the incidence of TSI negative GD in our population and to compare patients with TSI negative vs TSI positive GD.

METHODS

Charts of children with GD seen in our pediatric endocrinology clinic over the past 5 years were reviewed.

RESULTS

Fifty-seven patients with GD were included. TSI was negative in 43% of patients. No significant differences were found in children with TSI negative vs TSI positive GD.

CONCLUSIONS

In patients with GD, the finding of a negative TSI titer usually creates diagnostic uncertainty. However, the fact that nearly half of our patients with GD were TSI negative suggests that this is common in children.

Hashitoxicosis in children: clinical features and natural history

OBJECTIVE

To determine the incidence, natural history, and clinical characteristics of Hashitoxicosis (Htx) in pediatric patients with autoimmune thyroiditis.

STUDY DESIGN

Medical records of children diagnosed with Hashimoto thyroiditis between 1993 and 2002 were reviewed. The clinical course of patients presenting with hyperthyroidism was determined. Variables including sex, age, family history, thyroid hormone levels, anti-thyroid antibody titers, 123 I thyroid scan results, and presenting features were investigated as possible predisposing factors for the development of Htx.

RESULTS

Out of 69 patients with autoimmune thyroiditis, 8 were diagnosed with Htx. The duration of hyperthyroidism ranged from 31 to 168 days. Three patients became hypothyroid after an average of 46.3 +/- 13.2 days, and 5 patients became euthyroid after an average of 112.8 +/- 59.8 days. Additional findings included an elevated thyroid stimulating immunoglobulin (TSI) titer in 3 of the 8 patients with Htx, and increased uptake on 123 I scan in 2 patients.

CONCLUSION

Htx is an uncommon yet important cause of hyperthyroidism in children that has a variable clinical course. The diagnosis may be complicated, as presenting features sometimes exhibit significant overlap with Graves' disease. No factors predisposing to the development of Htx were identified.

Lower lid retraction: a valuable finding in juvenile Graves' orbitopathy

PURPOSE

To evaluate the findings of juvenile Graves' orbitopathy.

SUBJECTS AND METHODS

Retrospective evaluation of our patients with Graves' disease who are younger than 16 years.

RESULTS

Seventeen patients younger than 16 years were identified among 138 patients who were being treated for hyperthyroidism and goiter. Eleven (64.7%) of them had lid findings, orbital findings, or both and constituted 8.8% of the total of 125 such patients. Ophthalmic signs were common and were among the presenting signs in children with Graves' disease. Orbitopathy was mild and was more frequent in girls. Lower lid retraction and lag (ie, hesitation of the lower lids to follow upgaze) appeared to be constant and early findings.

CONCLUSION

Ophthalmologists and pediatricians should be aware of and look for lid signs in children presenting with related complaints and a history suggesting hyperthyroidism, goiter, or both.

Utilização do 131I no tratamento da doença de Basedow-Graves na infância e adolescência

Embora o diagnóstico da Doença de Graves (DG) na infância e adolescência seja relativamente fácil, seu tratamento ainda é controverso. Pode-se utilizar fármacos anti-tireoideanos (MMZ ou PTU), porém a incidência de efeitos adversos nessa faixa etária é maior que nos adultos e a taxa de remissão é baixa, mesmo com o uso prolongado. A cirurgia é pouco indicada como tratamento inicial, sendo realizada mais freqüentemente após recidiva do tratamento medicamentoso e/ou devido aos seus efeitos adversos. A utilização da radioiodoterapia na infância e adolescência vem crescendo. Com doses adequadas, ocorre o desenvolvimento de hipotireoidismo em cerca de 90% dos casos num período de 3 a 6 meses. Os dados iniciais sugerem que o tratamento em crianças acima de 5 anos não parece estar associado a maior risco de carcinoma de tireóide. A prevalência de efeitos adversos é menor que na cirurgia. Pacientes que apresentam fatores clínicos ou laboratoriais de pior prognóstico evolutivo podem ter seu tratamento medicamentoso encurtado, sendo a indicação da radioiodoterapia realizada mais precocemente.

The spectrum of thyroid diseases in childhood and its evolution during transition to adulthood: natural history, diagnosis, differential diagnosis and management

In this contribution, we review current knowledge on the pathogenesis, diagnosis and differential diagnosis of thyroid disorders in childhood and adolescence, as well as present an update on therapy methods and management guidelines for these disorders. This overview is conceptually divided into two parts, one focusing on thyroid functional disorders, i.e. conditions leading to hyper- and hypothyroidism, and another one pertinent to structural abnormalities of the thyroid gland, i.e. nodular disorders and thyroid cancer. Currently, congenital hypothyroidism is diagnosed in a much more timely fashion rather than in the past, rendering hypothyroidism-related mental retardation and developmental deficits very rare in newborns and children and, hence, diminishing significantly its public health impact. At the same time, considerable advances have occurred in our understanding of the molecular basis of several genetic conditions affecting the thyroid gland in childhood, such as familial non-autoimmune hyperthyroidism, as well as of the pathways leading to thyroid neoplasia.

Graves' disease in childhood

The vast majority of thyrotoxicosis cases in children are caused by Graves' disease (GD) and these account for 10-15% of all childhood thyroid diseases. The major clinical features of thyrotoxicosis in children are, in general, similar to those in adults. As in adults, the three conventional methods of treatment are antithyroid drugs (ATD), thyroidectomy and ablative radioiodine (131I). Although ATD are associated with side effects and a high relapse rate even after prolonged therapy, they still seem to be chosen as the first line of therapy for GD in childhood by most pediatric endocrinologists, although some have started using 131I as their first therapeutic modality. However, when ATD therapy has to be discontinued, or after relapse which may occur during or following ATD therapy, a definitive mode of therapy has to be chosen. Since thyroidectomy has the disadvantages of hospitalization and surgical complications, there is now an increasing tendency to advocate radioiodine as a choice of treatment in children older than five years old who achieve a high rate of remission. It should be kept in mind that with both thyroidectomy and radioiodine treatment, permanent hypothyroidism is very common and requires lifelong replacement therapy. According to the long-term follow-up data which have been published, radioiodine treatment in older children and adolescents seems to be safe and effective. Although studies of children with GD treated with ablative doses of radioiodine have not revealed an apparent increased risk of thyroid malignancy, a long-term study of larger populations is needed in order to define the true incidence of thyroid neoplasia, and other possible side effects, in children treated with radioiodine. Although the relatively low risks, low cost and practicability of radioiodine treatment has favored this therapy for children, as it has for adults, in the United States, it is still less attractive for European physicians. Progress in the immunological understanding of GD and of its genetic background will hopefully elucidate the pathways leading to GD, as well as the factors determining who is at high risk of developing GD, and may thus ultimately promote novel strategies for a more successful and safe therapy.

Special features of Graves' disease in early childhood

Graves' disease (GD) is extremely rare in children younger than 4 years of age, but if not recognized and treated it can seriously interfere with growth and development. We report three unrelated children, all females, in whom GD occurred before the age of 3. These children presented with goiter, exophthalmos, tachycardia, and hyperactivity. Moreover, one showed a severe psychomotor delay, and had previously undergone surgery due to craniosynostosis; the other two manifested a language delay. All had high thyroid hormones and thyrotropin receptor antibody (TRAb) serum levels that clearly indicated autoimmune hyperthyroidism. In all of them, the disease presumably had developed during the first or second year of life. No maternal history of GD was present in two. The third child was born to a mother affected with GD during pregnancy, but it is likely that her GD began to develop after 6 months of life. These children are being treated with methimazole, and treatment is still necessary after 32 months. TRAb levels were persistently high at follow-up. Psychological evaluation including language development at follow-up was appropriate for age in two children; the third child improved, but severe mental retardation is still evident. GD assessment in early childhood also needs to focus on psychological evaluation. Pediatricians should be aware of the possibility of permanent brain damage and craniosynostosis due to hyperthyroidism in infancy.

Common childhood thyroid disorders

This article presents current knowledge about common childhood thyroid gland disorders. Included are congenital and acquired hypothyroidism, hyperthyroidism, disorders due to iodine deficiency, tumors and miscellaneous conditions. The significance of early diagnosis by screening and institution of treatment of congenital hypothyroidism is emphasized. Etiology, pathogenesis, clinical signs and symptoms, diagnosis and treatment are discussed.

Attentional processing in hyperthyroid children before and after treatment

To determine whether specific components of attentional processing may be differentially disrupted during thyrotoxicosis, nine children with hyperthyroidism were assessed for intelligence and attention before and after one year of therapy. The attention test allowed for measurement of sustain, disengage, and shift subcomponents of attentional processing. Comparison with pediatric controls revealed lower nonverbal intelligence during thyrotoxicosis, which improved to normal following euthyroidism. On the attention task, an effect was observed during thyrotoxicosis only on the shift and disengage functions of attentional processing but not sustain. Attention results were unrelated to self-reported anxiety at time of testing. Results are discussed in terms of thyroid hormone activation of the prefrontal cortex, which is thought to be the cerebral substrate underlying the shift and disengage functions of attentional processing.