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Correspondence

Indian Pediatr 2017;54: 420-421

Acquired Hypothyroidism in a Newborn Treated with Amiodarone in the First Week of Life

 

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]
 

  


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 14th 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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