Association between thyroxine levels at birth and choanal atresia or stenosis among infants in Texas, 2004-2007.

BACKGROUND: The causes of choanal atresia or stenosis (CA) are largely unknown. Infant thyroxine (T(4) ) levels collected during newborn screening may be proxy measures for a risk factor present during the critical period of development. Therefore, we conducted a case-control study to examine the association between newborn T(4) levels and CA. METHODS: Data for cases with CA and controls were obtained from the Texas Birth Defects Registry for the period of 2004 to 2007. Information on infant T(4) levels at birth was obtained from the Texas Newborn Screening Program. Controls (n = 3570) were drawn from unaffected births in Texas for the same period and frequency matched to cases (n = 69) on year of birth, then linked to the newborn screening database. Logistic regression was used to evaluate the association between continuous and categorical infant T(4) levels and nonsyndromic CA. RESULTS: After adjustment for gestational age and year of birth, infant T(4) levels were inversely associated with CA (adjusted odds ratio [AOR], 0.85; 95% confidence interval [CI], 0.80-0.90). We observed a linear trend (p < 0.001) across quartiles of T(4) ; compared to infants with low levels, AORs for CA were 0.50 (95% CI, 0.28-0.91), 0.39 (95% CI, 0.20-0.75), and 0.15 (95% CI, 0.06-0.40) for infants with medium-to-low, medium, and high levels, respectively. CONCLUSIONS: Our findings suggest a role of low thyroid hormone levels in the development of CA, or that low newborn T(4) levels are potential proxy measures of a risk factor present during the critical period. Birth Defects Research (Part A), 2012.

The association between neonatal thyroxine and craniosynostosis, Texas, 2004-2007.

BACKGROUND: Craniosynostosis (CS), a structural anomaly characterized by premature fusion of cranial sutures, occurs in 1 in 2000 live births. Associations of CS with the thyroid have been reported. Neonatal thyroid hormone (T4) is evaluated nationally at birth by the Newborn Screening Program (NBS). This study evaluated the relationship between NBS T4 levels and craniosynostosis. METHODS: Live-born singleton babies born in 2004 through 2007 were identified through the Texas Birth Defects Registry (499 cases) and Texas Bureau of Vital Statistics (3570 controls) and successfully linked to analyte data available in the Texas NBS Database. Cases were classified based on the absence of other major defects (isolated cases, n = 382) and suture(s) involved. Mean T4 levels were compared between controls and cases (overall and stratified by classification). T4 levels were stratified by quintiles to evaluate differences between cases and controls within quintiles. The diagnostic utility of NBS T4 was evaluated using receiver operator characteristic (ROC) curves. RESULTS: Mean T4 levels were lower in isolated cases (16.89 µg/dl) than in controls (17.77 µg/dl; p = 0.0004). This trend persisted for sagittal (16.69 µg/dl; p = 0.002) and metopic (16.83 µg/dl; p = 0.042) CS. When stratified by quintiles, 54% of isolated lambdoid CS were in the first quintile compared to controls (p = 0.012). ROC area under the curve (AUC) was approximately 0.55 for all classifications except lambdoid (AUC = 0.73). CONCLUSION: NBS T4 levels were slightly lower among cases with nearly half of all lambdoid CS having T4 levels in the lowest quintile. However, overall NBS T4 levels are not suitable for potential screening or diagnostic application.