The Impact of Transient Hypothyroidism on the Increasing Rate of Congenital Hypothyroidism in the United States

Abstract

The reported incidence rate of primary congenital hypothyroidism (CH) has been increasing in the United States over the past 2 decades. We have considered the possibility that the inclusion of cases of transient hypothyroidism has inflated the reported incidence rate of CH. Assessing the effects of cases of transient hypothyroidism on the incidence rate is problematic, because the definitions, diagnostic criteria, and differentiation from transient hyperthyrotropinemia vary widely among state newborn screening programs. Among the 4 etiologies for transient hypothyroidism (maternal thyrotropin receptor-blocking antibodies, exposure to maternal antithyroid medications, iodine deficiency, and iodine excess), there is little evidence of increases in the incidence rate from thyrotropin receptor-blocking antibodies. Exposure to antithyroid drugs could contribute significantly to the incidence rate of transient CH, given the high estimated incidence of active maternal hyperthyroidism. Iodine deficiency or excess in the United States seems unlikely to have contributed significantly to the incidence rate of CH, because the secular trend toward lower iodine intake among women of reproductive age in the 1980s and 1990s seems to have plateaued, and perinatal iodine exposure has presumably declined as a result of recommendations to discontinue using iodinecontaining disinfectants. Although the female-to-male sex ratio among newborns with thyroid agenesis or dysgenesis (the most common causes of CH) is typically 2:1, analysis of the sex ratio of newborns diagnosed with presumed CH in the United States suggests that a substantial proportion might have transient hypothyroidism or hyperthyrotropinemia, because the sex ratio has been well below the expected 2:1 ratio. Combined ultrasonography and 123 I scintigraphy of the thyroid gland are effective tools for identifying cases of thyroid agenesis and dysgenesis and can help to differentiate cases of transient hypothyroidism from true CH. Imaging is also a vital component in evaluating children who, at 3 years of age, undergo a trial of discontinuation of levothyroxine treatment to test for persistence of hypothyroidism. Ultimately, thyroid gland imaging, in conjunction with longterm follow-up studies that appropriately assess and report whether there was permanence of hypothyroidism, will be necessary to address the true incidence rate of CH and any contribution to the observed rate by transient cases of hypothyroidism or hyperthyrotropinemia.

Transient neonatal hyperthyrotropinemia is a risk factor for developing persistent hyperthyrotropinemia in childhood with repercussion on developmental status

“…TNH should be differentiated from a false-positive screening test, defined as an abnormal screening test value, with normal results of serum tests taken immediately afterward. Obviously, these results should not be understood as an abnormal condition (6). TNH should be interpreted with caution in newborns, to assess the risk of unnecessary treatment, including: effects on brain development, hyperactivity, advancement in bone age, and craniosynostosis (7).…”

Морфофункціональний Стан Щитоподібної Залози В дітей З Уродженим Гіпотиреозом

“…Аналіз даних літерату-ри свідчить про те, що захворювання ЩЗ займають перше місце серед усієї ендокринної патології і до цих пір залишаються однією з найбільш склад-них проблем у клінічній ендокринології та ендо-кринній хірургії [2]. Це підтверджується неухиль-но зростаючим рівнем захворюваності, а також стійко високими показниками інвалідизації при цій патології, що пов'язано з погіршенням еко- Згідно з результатами великого популяційного дослідження NHANES-III, проведеного в США, се-ред осіб старше 12 років поширеність маніфестно-го ГТ становить 0,3 %, а субклінічного -4,3 % [6]. Протягом року 5-10 % випадків латентного ГТ пе-реходять у маніфестний, а його частота зростає зі збільшенням віку обстежуваних і в популяції літніх людей може досягати 7-26 % [7].…”

“…У загальній Гіпоплазія ЩЗ 34,43 ± 9,81 29,80 [5,4] 6,65 ± 2,52 5,85 [2,[2][3][4][5][6][7][8][9][10][11][12]7] 11,13 ± 2,27 9,65 [7,[5][6][7][8][9][10][11][12][13][14][15][16][17]7] ЩЗ розташована в типовому місці 9,11 ± 1,40 6,81 [2,[7][8][9][10][11][12][13][14][15]6] 12,15 ± 1,10 8,85 [4,[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]…”

“…В останнє десятиліття з'явилося багато робіт, присвячених проблемі ГТ, які змінили наші погля-ди на всю патологію ЩЗ [4][5][6]. Це пов'язано перш…”

Thyroid “Vise” in an Infant With Neonatal Graves’ Disease

“…Neonatal hypothyroidism due to transplacental passage of maternal antibodies occurs in 1 in 180 000 live births. 2 Estimates of the frequency of neonatal hyperthyroidism due to maternal Graves' disease (GD) vary widely, with estimates of 6 to 24 in 10 000 live births. 3 Neonatal goiter has been reported in association with neonatal GD, 4 and airway compromise has been described in hypothyroidism-associated neonatal goiter.…”