Usefulness of thyroid function assessment in infants born to mothers with thyroid dysfunction during pregnancy

Abstract

Introduction: Maternal thyroid disease is considered as a risk factor for abnormal thyroid function at birth as well as for long-term morbidity in offspring. The potential harmful effects on the neonate had led to the clinical practice of thyroid function assessment in infants born to mothers with thyroid disease during pregnancy. We evaluated the usefulness of routine thyroid function tests for every newborn of a mother with thyroid dysfunction. Methods: Data were collected retrospectively from the medical files of mothers diagnosed with thyroid disease and their infants (496 mother–neonate pairs). All mothers with diagnosed thyroid disease who gave birth in the years 2016–2019 at our medical center were included. Results: Hypothyroidism was the most common maternal diagnosis (91.4%), among which 48.7% had Hashimoto's thyroiditis. Hyperthyroidism was diagnosed in 8.6% of the cohort; 71.6% of them with Graves' disease. None of the newborns was diagnosed with congenital hypothyroidism in the screening program. Thyroid-stimulating hormone was >10 mIU/l in 14.6% and >20 mUI/l in 2.2%; all had free thyroxine within normal range. Serum thyroid function test identified four infants with thyroid disease: two had congenital hypothyroidism not related to maternal thyroid disease, one had transient familial congenital hypothyroidism and one had neonatal Graves' disease. Conclusions: Thyroid function testing for all newborns of mothers with thyroid dysfunction seems redundant. However, in cases of congenital hypothyroidism in siblings, thyroid function test, in addition to newborn thyroid screening, is recommended and more careful follow-up is indicated. In maternal Graves' disease, thyroid function test on day 2–3 of life is recommended.

A literature review on the redundancy of additional thyroid function tests in neonates of mothers with hypothyroidism

“…Among the studies included in this review, four have detected cases of CH with additional thyroid function tests that were missed during the initial screening programme. 20,[25][26][27] The largest of these was published in 2022 by Ben-Zeev et al and comprised 701 infants.…”

“…The third had a sibling with CH. 26 The authors suggested that thyroid function testing for all newborns of mothers with thyroid dysfunction is rather redundant. However, it may be useful in cases of a positive history of CH in siblings, along with a more careful follow-up.…”

“…However, it may be useful in cases of a positive history of CH in siblings, along with a more careful follow-up. 26 In a study by Underland et al comprising 352 infants, 3 patients that were not detected by a free thyroxine-based screening programme, were diagnosed with CH. 25 All three patients had normal free thyroxine levels and were classified as having subclinical hypothyroidism.…”

“…After additional testing the study revealed 87 newborns with TSH >10 mU/L but only 4 patients had CH, 3 of which were treated. 26 Another multicentre study in Italy comprised 291 newborns of mothers with autoimmune hypothyroidism. All infants had negative screening for CH while additional testing found 1 child that needed therapy with levothyroxine.…”

Eating Disorders: Causes, Symptoms, Diagnosis and Management

“…Electrolyte abnormalities are prevalent and must be assessed to rule out hyponatremia from excessive water consumption, hypokalemia from excessive purging, or hypocalcaemia and hypomagnesaemia from incorrect laxative usage. Thyroid function, as well as plasma ferritin, folate, and vitamin B12, should be evaluated (Ben-Zeev et al, 2022;D'Aurizio et al, 2022;Fang et al, 2022).…”