Severe hypothyroidism following a single topical exposure to iodine in a premature neonate. The authors describe a premature infant with severe hypothyroidism from topical exposure to iodine following a single surgical procedure at 28 days of life. A low free T4 level of 0.05 ng/dL and a high TSH level of 228 mIU/L was detected with an increased urinary iodine excretion level of 178 mg/L (reference range 0.30-1.97 mg/L). The thyroid ultrasound was normal. Levothyroxine was started immediately but thyroid function did not recover fully during admission and levothyroxine was required beyond term corrected. This case highlighted how susceptible extremely preterm infants are to iodine-induced hypothyroidism, even short-term topical exposure. Delayed treatment of hypothyroidism can lead to profound neurodevelopmental delay. As surgical advances allow for interventions at earlier gestations, the importance of early thyroid function testing postexposure to iodine is highlighted and ultimately topical iodine should be avoided in these susceptible infants.
A randomized, double-blind study of iodine supplementation during pregnancy in Sweden: pilot evaluation of maternal iodine status and thyroid function. Pregnant women in Sweden are mildly iodine deficient. The authors investigated the effect of daily iodine supplementation on the iodine and thyroid status of pregnant women in a pilot, randomized, double-blind trial. They recruited 200 thyroid-healthy pregnant women during early pregnancy and assigned (1:1) to daily intake of a multivitamin tablet with or without 150 μg of iodine. At baseline, the intervention and the control groups had similar median urinary iodine concentrations. The intervention group had higher median urinary iodine and lower median thyroglobulin compared to controls during the second and third trimester, respectively). Further study is needed to investigate the impact on the children's neuropsychological development.
Measurement of 17-Hydroxyprogesterone by LCMSMS Improves Newborn Screening for CAH Due to 21-Hydroxylase Deficiency in New Zealand. The positive predictive value of newborn screening for congenital adrenal hyperplasia due to 21-hydroxylase deficiency was <2% in New Zealand. This is despite a bloodspot second-tier immunoassay method for 17-hydroxyprogesterone measurement with an additional solvent extract step to reduce the number of false positive screening tests. The authors developed a liquid chromatography tandem mass spectrometry (LCMSMS) method to measure 17-hydroxyprogesterone in bloodspots to replace their current second-tier immunoassay method. Newborn screening performance was assessed by comparing screening metrics 2 years before and 2 years after LCMSMS implementation. Screening data analysis showed the number of false positive screening tests to be reduced from 172 to 40 in the 2 years after LCMSMS implementation. The positive predictive value of screening and screening specificity also increased significantly, indicating its value as a second-tier test for CAH due to 21-hydroxylase deficiency.
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