Toxicological considerations for antithyroid drugs in children

The Incidence of Childhood Thyrotoxicosis Is Increasing in Both Girls and Boys in Sweden

BACKGROUND

We found an increase in the incidence rate (IR) of childhood thyrotoxicosis (CT) during the 1990s in central Sweden. The optimal treatment method for CT is a subject that is still debated upon.

OBJECTIVES

To investigate whether the increase in IR of CT in Sweden persists and to study the treatment outcome.

METHOD

Children <16 years of age diagnosed with CT during 2000-2009 and living in 1 of 5 counties in central Sweden were identified retrospectively using hospital registers. Data on clinical and biochemical characteristics and outcomes of treatment were collected from medical records. The corresponding data from 1990 to 1999 were pooled with the new data.

RESULTS

In total, 113 children were diagnosed with CT during 1990-2009 in the study area. The overall IR was 2.2/100,000 person-years (95% CI 1.2-2.5/100,000 person-years). The IR was significantly higher during 2000-2009 than during 1990-1999 (2.8/100,000 [2.2-3.6] vs. 1.6/100,000 person-years [1.2-2.2], p = 0.006). The increase was significant for both sexes. Seventy percent of the patients who completed the planned initial treatment with antithyroid drugs (ATDs) and were not lost to follow-up relapsed within 3 years. Boys tended to relapse earlier than girls (6.0 months after drug withdrawal [95% CI 1.9-10.0] vs. 12.0 months [95% CI 6.8-17.3], p = 0.074).

CONCLUSIONS

The IR of CT is increasing in both girls and boys. Relapse rate after withdrawal of ATD treatment is 70%. Boys tend to relapse earlier than girls, and this needs to be further investigated.

Increasing Incidence of Juvenile Thyrotoxicosis in Denmark: A Nationwide Study, 1998-2012

AIM

The aim of this study was to determine in a Danish nationwide study whether the incidence rate (IR) of thyrotoxicosis in children below 15 years of age has increased between 1998 and 2012 and to compare the results with previously published national data from 1982 to 1988. Furthermore, we intended to conduct a descriptive study of children diagnosed with Graves' disease (GD) between 2008 and 2012.

METHODS

Children diagnosed with thyrotoxicosis between 1998 and 2012 were identified through the Danish National Patient Registry. All medical records were reviewed to verify the diagnosis. Additional data were collected on children diagnosed with GD in 2008-2012.

RESULTS

In total, 237 patients with juvenile thyrotoxicosis (JT) were identified. The overall IR in 1998-2012 was 1.58/100,000 person-years and has increased significantly from 0.79/100,000 person-years in 1982-1988 (p < 0.001). The IR has continued to increase during the recent 15 years (1.31-1.83/100,000 person-years), with a 12.5% increase with each 5-year time period. The IR increased with age and female sex (p < 0.001). The descriptive study included 79 children with GD, presenting with a wide spectrum of clinical features. Remission occurred in 13.9%.

CONCLUSION

The IR of JT has increased significantly since 1982-1988 and has continued to increase during the recent 15 years. The overall IR was 1.58/100,000 person-years during 1998-2012.

Management of Neonates Born to Mothers With Graves' Disease

Neonates born to mothers with Graves' disease are at risk for significant morbidity and mortality and need to be appropriately identified and managed. Because no consensus guidelines regarding the treatment of these newborns exist, we sought to generate a literature-based management algorithm. The suggestions include the following: (1) Base initial risk assessment on maternal thyroid stimulating hormone (TSH) receptor antibodies. If levels are negative, no specific neonatal follow-up is necessary; if unavailable or positive, regard the newborn as "at risk" for the development of hyperthyroidism. (2) Determine levels of TSH-receptor antibodies in cord blood, or as soon as possible thereafter, so that newborns with negative antibodies can be discharged from follow-up. (3) Measurement of cord TSH and fT4 levels is not indicated. (4) Perform fT4 and TSH levels at day 3 to 5 of life, repeat at day 10 to 14 of life and follow clinically until 2 to 3 months of life. (5) Use the same testing schedule in neonates born to mothers with treated or untreated Graves' disease. (6) When warranted, use methimazole (MMI) as the treatment of choice; β-blockers can be added for sympathetic hyperactivity. In refractory cases, potassium iodide may be used in conjunction with MMI. The need for treatment of asymptomatic infants with biochemical hyperthyroidism is uncertain. (7) Assess the MMI-treated newborn on a weekly basis until stable, then every 1 to 2 weeks, with a decrease of MMI (and other medications) as tolerated. MMI treatment duration is most commonly 1 to 2 months. (8) Be cognizant that central or primary hypothyroidism can occur in these newborns.

Acute liver failure associated with propylthiouracil in a pregnant 26-year-old woman

It seems appropriate to use propylthiouracil to treat maternal hyperthyroidism during the first trimester of pregnancy. We present the case of a 26-year-old woman with acute liver failure associated with propylthiouracil during the first trimester of pregnancy. She was successfully treated without liver transplantation. Attention should be paid to the possible occurrence of propylthiouracil-induced hepatotoxicity even during the first trimester of pregnancy.

Peripheral blood lymphocyte apoptosis and its relationship with thyroid function tests in adolescents with hyperthyroidism due to Graves' disease

INTRODUCTION

Failures in apoptotic pathways can contribute to various autoimmune diseases, including autoimmune hyperthyroidism due to Graves' disease (GD). The aim of the present research was to assess changes in the degree of peripheral blood (PB) lymphocyte apoptosis during methimazole (MMI) treatment in the group of teenage children, and to describe its relationship with thyroid function tests.

MATERIAL AND METHODS

The percentage of PB apoptotic lymphocytes, assessed by the decrease in mitochondrial transmembrane potential (CMXRos staining), was measured in 30 adolescents at the time of diagnosis and after obtaining normalization of the thyroid hormone levels.

RESULTS

The percentage of apoptotic lymphocytes in previously untreated patients with GD (5.16 ±2.81%) was significantly lower (p = 0.000001) than the percentage of apoptotic cells in the same group of patients after obtaining methimazole-induced euthyroidism (10.72 ±4.66%). There was a correlation between the increase of the mean percentages of apoptotic lymphocytes and the reduction of FT4 levels (R = 0.63, p < 0.0001), as well as the reduction of TT3 levels (R = 0.95, p < 0.0001). The more signs and symptoms accompanying the diagnosis of GD, the higher was the increment of the degree of lymphocyte apoptosis observed during the MMI-treatment (R = 0.74, p < 0.0000001). The methimazole dosage correlated (R = 0.85, p < 0.0001) with the percentage of apoptotic cells.

CONCLUSIONS

The use of methimazole in treatment of hyperthyroidism due to GD leads to an increment of apoptotic cells in PB. Higher doses of methimazole cause a higher increase of apoptotic lymphocytes. Apoptosis induction of human PB lymphocytes seems to be one of the indicators of proper hyperthyroidism treatment.

Congenital disorders of the thyroid: hypo/hyper

This article summarizes the ontogenesis and genetics of the thyroid with regards to its possible congenital dysfunction and briefly refers to the roles of the mother-placenta-fetal unit, iodine effect, and organic and functional changes of the negative feedback mechanism, as well as maturity and illness, in some forms of congenital hypo- and hyperthyroidism. This article also describes the published literature and the authors' data on the clinical aspects of congenital hypothyroidism, on the alternating hypo- and hyperthyroidism in the neonatal period, and on neonatal hyperthyroidism.