Newborn Screening for Primary Congenital Hypothyroidism: Estimating Test Performance at Different TSH Thresholds

Area of Science:

• Endocrinology
• Pediatrics
• Public Health

Background:

• Congenital hypothyroidism (CH) requires early detection and treatment to prevent developmental issues.
• Newborn bloodspot screening programs are crucial for identifying CH in infants.
• Optimizing screening test thresholds is essential for accurate diagnosis and effective public health policy.

Purpose of the Study:

• To evaluate the performance of newborn screening for CH at various thyroid-stimulating hormone (TSH) test thresholds.
• To determine the incidence of primary CH in a multiethnic population.
• To compare the diagnostic accuracy of TSH thresholds of 6 mU/L and 8 mU/L against the national standard of 10 mU/L.

Main Methods:

• Prospective surveillance of newborns undergoing CH screening from June 2011 to June 2012.
• Analysis of TSH levels in bloodspots and 3-year follow-up to confirm permanent CH status.
• Calculation of relative likelihood ratios (rLRs) to assess different TSH thresholds.

Main Results:

• The incidence of permanent CH was 5.3 per 10,000 infants.
• At locally applied thresholds, sensitivity was 96.76%, specificity 99.97%, and positive predictive value 66.88%.
• A TSH threshold of 8 mU/L showed a higher positive rLR (1.20) compared to 10 mU/L, suggesting improved detection.

Conclusions:

• The current newborn screening program for CH demonstrates good performance.
• A TSH threshold of 8 mU/L warrants further investigation as a potentially superior alternative to the national standard of 10 mU/L.
• Future research should consider the impact of transient CH on screening policies.