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Updated: Apr 5, 2026
Assessment and Evaluation of the High Risk Neonate: The NICU Network Neurobehavioral Scale
Published on: August 25, 2014
Single newborn screen or routine second screening for primary congenital hypothyroidism
Stuart K Shapira1, Cynthia F Hinton1, Patrice K Held2
1National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA, USA.
Insights
Newborn screening for congenital hypothyroidism (CH) shows higher detection rates in one-screen states. Two-screen states detect 11.5% of CH cases on the second screen, highlighting the need for careful program evaluation.
Area of Science:
- Biochemistry
- Pediatrics
- Public Health
Background:
- Newborn screening protocols vary across U.S. states, with some employing one screen and others two.
- Congenital hypothyroidism (CH) is a treatable condition detectable through newborn screening.
Purpose of the Study:
- To compare the effectiveness of one- vs. two-stage newborn screening for primary congenital hypothyroidism (CH).
- To analyze screening consequences based on laboratory practices and case characteristics.
Main Methods:
- Retrospective analysis of individual-level medical and biochemical data for 2251 CH cases in selected one- and two-screen states.
- Collection and analysis of aggregate data on screened newborns' characteristics.
Main Results:
- One-screen states demonstrated a higher detection rate for primary CH.
- In two-screen states, 11.5% of CH cases were identified during the second screening round.
- Race/ethnicity emerged as a significant factor influencing CH detection timing between the first and second screens.
Conclusions:
- A single newborn screen may miss cases of CH, particularly in certain racial/ethnic groups.
- Transitioning two-screen states to a single screen without algorithm modification risks delayed CH diagnosis.
- Two-screen states could potentially adopt single-screen protocols for CH without compromising performance through appropriate method and algorithm adjustments.
Abstract:
Routine second screening of most newborns at 8-14 days of life for a panel of newborn conditions occurs in 12 U.S. states, while newborns in the other states typically undergo only a single routine newborn screen. The study objective was to evaluate screening consequences for primary congenital hypothyroidism (CH) in one- and two-screen states according to laboratory practices and medical or biochemical characteristics of screen-positive cases. Individual-level medical and biochemical data were retrospectively collected and analyzed for 2251 primary CH cases in one-screen (CA, WI) and two-screen (AL, DE, MD, OR, TX) states. Aggregate data were collected and analyzed for medical and biochemical characteristics of all screened newborns in the states. Among the states evaluated in this study, the detection rate of primary CH was higher in the one-screen states. In the two-screen states, 11.5% of cases were detected on the second screen. In multivariate analyses, only race/ethnicity was a significant predictor of cases identified on the first versus second screen, which likely reflects a physiologic difference in primary CH presentation. Newborn screening programs must heed the potential for newborns with CH not being detected by a single screen, particularly newborns of certain races/ethnicities. If the two-screen states converted to a single screen using their current algorithms, newborns currently identified on the routine second screen would presumably not be detected, resulting in probable delayed diagnosis and treatment. However, based on the one-screen state experiences, with appropriate modifications in screening method and algorithm, the two-screen states might convert to single screen operation for CH without loss in performance.
