The utility of newborn TSH

The utility of newborn TSH and 17-OHP levels in addition to Hb ratios in model performance was also explored. Similar to hemoglobin, TSH and 17-OHP offer practical advantages as they may be routinely obtained by fluorometric or colorimetric assay rather than by mass spectrometry analysis. These analytes are also likely to be captured in existing newborn screening programs (Therrell et al., 2015) due to the frequency of related disorders and effectiveness of treatment. In our study, addition of TSH and 17-OHP improved model accuracy over and above that of the simple Hb model and demonstrated excellent predictive ability in SGA10 infants. The latter is particularly important in low resource settings where it urat1 inhibitor may be difficult to distinguish infants who are small as a result of preterm birth or placental insufficiency. Although the effect of SGA10 on Hb ratio in the current study were not explored, preliminary examination of metabolic profiles derived from infants born to a tertiary care hospital with a diagnostic code of \'placental insufficiency\' revealed no significant difference in Hb ratio. The disadvantages of relying on TSH and 17-OHP for gestational age prediction must also be considered. TSH and 17-OHP are subject to rapid postnatal change, and are thus typically sampled after analyte levels stabilize (Newborn Screening Ontario - Dépistage Néonatal Ontario, 2013). Thus it is unlikely that prediction models requiring such analyte measurements would be useful in infants who are discharged prior to 24h, nor would the model be appropriate to cord blood-derived samples for the same reason. While we found that models utilizing a full panel of newborn screening analytes were the most precise at predicting continuous GA than limited Hb models, the performance characteristics of our Hb models to discriminate ≥34 versus <34weeks gestational age are promising. Thirty-four weeks gestational age is an important clinical threshold as it represents the lower limit of the late preterm period (Kugelman and Colin, 2013; Bakewell-Sachs, 2007). It is above this threshold that the health risks of preterm infants are reduced, although still remaining elevated compared to their term counterparts (Nold et al., 2011). Thus, the trade-off between minor reduction in model accuracy with reduced cost and expertise required to obtain model variables may make hemoglobin-based metabolic prediction models for gestational age suitable substitutes to postnatal metabolic gestational dating in jurisdictions where full mass spectrometry screening is not available.
Conclusions
Funding Sources This study was funded by a Phase II Grand Challenges Exploration grant from the Bill & Melinda Gates Foundation (OPP1141535). The funding agency had no role in the study design, data collection, analyses, interpretation or writing of the report. No payments were received to write this article by a pharmaceutical company or other agency. No payments were received to write this article by a pharmaceutical company or other agency.
Conflict of Interest
Author Contributions
Acknowledgements