IODINE AND HYPOTHYROIDISM IN NEONATES WITH CONGENITAL HEART-DISEASE

Aim-To evaluate the influence of the intravenous injection of iodine d uring cardiac catheterisation, and of topical iodine antiseptics durin g surgical procedures, on thyroid function in full term neonates. Meth ods-Twenty one full term infants with major cardiac anomalies who surv ived for more than a month were studied. Thyroxine and thyrotropin con centrations were measured (by radioimmunoassay) before each procedure, 24 hours after the procedure, and every week thereafter until the age of 1 month or until normal. Thyroxine values less than 64.4 nmol/l we re considered low, while thyrotropin values greater than 30 mU/l were considered high. Results-Thyroid function tests before iodine exposure were within normal limits in all infants. Following catheterisation o r surgery six infants had raised thyrotropin concentrations; three had low thyroxine concentrations. Two of those infants were treated with L-thyroxine. Conclusion-Iodine exposure during cardiac catheterisation or surgery may induce transient hypothyroidism in term infants.