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Indian Pediatr 2017;54: 420-421 |
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Acquired Hypothyroidism in a Newborn Treated
with Amiodarone in the First Week of Life
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Emilio García-García and *Rosa Domínguez-Gutiérrez De
Ceballos
From Unidad de Pediatría and *Servicio de Bioquímica
Clínica, Hospital Universitario "Virgen del Rocío", Seville. Spain.
Email: [email protected]
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The amiodarone molecule contains iodine. An overload of this element
("Wolff-Chaikoff" effect) can cause hypothyroidism at all ages; newborn
infants are especially susceptible
[1].
We describe a case of early-onset acquired
hypothyroidism in a premature newborn who received amiodarone after a
week of life. Fetal tachycardia was diagnosed at 24th week of gestation
and the mother was treated with digoxin until cesarean section at 34th
week. Junctional ectopic tachycardia was confirmed by an
electrocardiogram at birth, and amiodarone infusion was administered to
the infant from the first day of life. Thyroid function was normal in
sample collected for universal screening on the third day. However, on
the 14 th day thyrotropin
increased to 109 mU/L, with low free thyroxine levels (0.83 ng/dL). We
started levothyroxine (10 µg/kg/day). The thyroid imaging was normal,
antithyroglobulin and antiperoxidase antibodies were negative, and
urinary iodine was very high (969 µg/L). Levothyroxine normalized
thyroid function after a month of treatment (thyrotropin 3.5 mU/L and
free thyroxine 1.52 ng/dL) it was discontinued at 10 months, maintaining
normal thyroid function four years later (thyrotropin < 5 mU/L).
The thyroid gland of both fetus and newborn infants
is most affected by an iodine overload. When amiodarone is administered
in pregnant women due to maternal or fetal arrhythmias, it can reach the
fetus transplacentally, inducing a transient congenital hypothyroidism
and, in some cases, compensating goiter [2]. However, reported cases of
acquired hypothyroidism after postnatal amiodarone administration are
very less [3,4]. There was complete recovery of thyroid function in all
of them several months after medication removal.
Guidelines recommend monitoring thyroid function
before starting amiodarone, and after six months in adult patients [5].
However, there are no such recommen-dations for children. In childhood,
especially in younger ages, these surveillance intervals of thyroid
function should be much shorter. Among children under four years of age,
some authors recommend determining thyroid hormones at baseline, weekly
during the first month of treatment, monthly during the first quarter,
and then quarterly [4]. We agree with these recommendations, taking into
account how quickly hypothyroidism is established in neonates and young
infants exposed to amiodarone.
References
1. Bogazzi F, Bartalena L, Gasperi M, Braverman LE,
Martino E. The various effects of amiodarone on thyroid function.
Thyroid. 2001;11:511-9.
2. Bartalena L, Bogazzi F, Braverman LE, Martino E.
Effects of amiodarone administration during pregnancy on neonatal
thyroid function and subsequent neurodevelopment. J Endocrinol Invest.
2001;24:116-30.
3. Knirsch W, Kretschmar O, Vogel M, Uhlemann F,
Bauersfeld U. Successful treatment of atrial flutter with amiodarone in
a premature neonate. Case report and literature review. Adv Neonatal
Care. 2007;7:113-21.
4. Trudel K, Sanatani S, Panagiotopoulos C. Severe
amiodarone-induced hypothyroidism in an infant. Pediatr Crit Care
Med. 2011;12:e43-5.
5. Epstein AE, Olshansky B, Naccarelli GV, Kennedy JI Jr, Murphy EJ,
Goldschlager N. Practical management guide for clinicians who treat
patients with amiodarone. Am J Med. 2016;129:468-75.
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