175: The effect of subclinical hypothyroidism on IQ in seven to eight year old children

Abstract

IQ in seven to eight year old children Niamh Murphy, Mairead Diviney, Jennifer Donnelly, Sharon Cooley, Colin Kirkham, Adrienne Foran, Fionnuala Breathnach, Fergal Malone, Michael Geary Rotunda Hospital, Department of Obstetrics and Gynaecology, Dublin, Ireland, Rotunda Hospital, Department of Neonatology and Paediatrics, Dublin, Ireland, Rotunda Hospital, Department of Statistics, Dublin, Ireland, National University of Ireland, Maynooth, Department of Psychology, Co. Kildare, Ireland OBJECTIVE: In our practice, pregnant women are not routinely screened or treated for subclinical hypothyroidism (SCH), although overt hypothyroidism is treated. Our objective was to compare the IQ of children whose mothers had been diagnosed with SCH antenatally (in a prior observational trial) with closely matched controls. STUDY DESIGN: In a previous study from our group, 1000 healthy nulliparous patients were screened anonymously for SCH. Those with overt hypothyroidism were informed and treated, whereas those with SCH were contacted postnatally for paediatric follow-up. SCH (defined as reduced free T4 with normal TSH, or normal free T4 with raised TSH) was found in 4.6% (n 46) of the study population. These cases were matched for gestational age, gender and mode of delivery with 47 controls. All children underwent a formal neurodevelopmental assessment at age 7 to 8 years by a single psychologist blinded to the original maternal thyroid status. WISC-IV assessment scores were used to compare the groups. RESULTS: From the cohort of cases, 23 mothers agreed to assessment of their children as well as 47 controls. The children in the control group had higher mean scores than those in the case group across the categories of Verbal Comprehension Intelligence, Perceptual Reasoning Intelligence, Working Memory Intelligence, Processing Speed Intelligence and Full Scale IQ. Mann Whitney U testing confirmed a statistically significant difference in IQ between the cases (composite score 103.87) and the controls (composite score 109.11) This had a 95% confidence interval (.144, 10.330). CONCLUSION: Our results highlight significant differences in IQ of children of mothers who had unrecognised SCH during pregnancy. While our study size and design prevents us from making statements on causation, our data suggests significant potential public health implications in terms of routine thyroid function screening in pregnancy. The results of prospective intervention trials to address a causative association will be vital to address this issue. 176 Perinatal risk factors for severe hypoxic-ischemic encephalopathy in neonates treated with whole body hypothermia Christopher Wayock, Benjamin Greenberg, Jacky Jennings, Frances Northington, Ernest Graham Johns Hopkins University School of Medicine, Division of Maternal-Fetal Medicine, Department of Gynecology and Obstetrics, Baltimore, MD, Johns Hopkins University School of Medicine, Division of Neonatology, Department of Pediatrics, Baltimore, MD, Johns Hopkins University School of Medicine, Department of Pediatrics, Baltimore, MD OBJECTIVE: Whole body hypothermia has been shown to reduce the risk of death or neurologic injury in neonates with hypoxic-ischemic encephalopathy (HIE). However, newer regimens and other therapies may also benefit the most severely injured neonates. Our objective is to identify perinatal risk factors that identify the most severely injured neonates. STUDY DESIGN: A case-control study was conducted from 1/2007 to 5/2012 among 104 neonates 35 weeks with suspected HIE treated with whole body hypothermia of which 99 underwent an MRI at 7-10 days of life. Of the 5 neonates that did not have an MRI 3 died. 39% were born within our system, and 61% were transferred. Cases were defined as those neonates who died or had an abnormal brain MRI at 7-10 days. Controls were surviving neonates with a normal MRI. Logistic regression models were used to determine the predictive value of factors hypothesized to impact neurologic injury. RESULTS: Cases and controls did not differ on gestational age, birthweight, mode of delivery, sentinel events, initial neonatal blood gas, positive neonatal blood cultures, histologic chorioamnionitis, funisitis or diagnosis of nonreassuring fetal heart rate prior to delivery. Cases were significantly more likely to have an abruption, a cord blood gas showing metabolic acidosis, elevated initial neonatal WBC count and seizures. In multivariable logistic regression, decreased cord pH (p 0.001) and increased initial neonatal WBC count (p 0.026) predicted an increased risk of neurologic injury. Cord pH and initial neonatal WBC count can predict an abnormal brain MRI with a sensitivity of 59.4%, specificity of 77.6%, positive predictive value of 66.7% and negative predictive value of 71.7%. CONCLUSION: Worsening metabolic acidosis in cord blood at birth and elevated initial neonatal WBC correlate with neurologic injury among neonates with HIE treated with whole body hypothermia. These cases may be candidates for new hypothermia regimens as well as other therapies.