Goiter in a newborn exposed to lithium in utero.

OBJECTIVE: To report a case of neonatal goiter and biological hypothyroidism in a newborn exposed to lithium in utero resulting from therapy given to the mother before and during her pregnancy.

CASE SUMMARY: A male neonate, born at 37 weeks' gestation, presented with a goiter without other signs of hypothyroidism. His serum thyroid-stimulating hormone concentration was high and unbound tetrathyroxine concentration was low, indicating that chronic exposure to lithium was present. Oral thyroxine treatment was initiated when the infant was 3 days old and continued for 11 weeks. Treatment was effective in reducing the goiter and hormone concentrations, and allowing normal growth and psychomotor development during the following 3.5 months. Other drugs taken by the mother during pregnancy are not known to induce thyroid abnormalities.

DISCUSSION: Lithium is used for prophylaxis and treatment of bipolar disorder. Goiter and hypothyroidism in adults have been described in patients treated with lithium; thyroid disorders are reversible if lithium is discontinued. Few cases of goiter and hypothyroidism have been reported in newborns exposed to lithium in utero. In our patient, congenital hypothyroidism required longer thyroxine treatment than lithium-induced thyroid disorders. The delay before improvement seems to be similar to that observed in adults. The Naranjo probability scale indicated that lithium was the probable cause of hypothyroidism resulting from in utero exposure.

CONCLUSIONS: Lithium is a well-known goitrogenic agent. Thus, if lithium treatment needs to be continued during pregnancy in women with bipolar disorder, adequate screening for morphology by ultrasonography and systematic hormonal biological control in newborns are recommended.