The relation between serum and filter paper TSH level in neonates with congenital hypothyroidism

BACKGROUND: the aim of this study was to determine the relation between serum and filter paper thyroid-stimulating hormone (TSH) levels in neonates with congenital hypothyroidism (CH). We also tried to determine an appropriate cutoff point of filter TSH for recalling screened neonates. MATERIALS AND METHODS: in this descriptive-analytic study, records of 2283 neonates who had been recalled during CH screening program in Isfahan (Iran) were studied. The relation between serum and filter paper TSH levels in the studied neonates was assessed and the best cutoff point of filter TSH and its sensitivity and specificity for proper diagnosis of CH were determined. RESULTS: among the studied neonates, 103 (4.5%) were diagnosed with CH. Using receiver operating characteristic (ROC) curve, the best cutoff point for diagnosing CH was 7.5 with a sensitivity of 74.8% and specificity of 71.3%. The rates of false positive and false negative diagnoses at this cutoff point were28.7% and 25.2%, respectively. There was a significant relationship between serum and filter paper TSH levels. CONCLUSION: the cutoff point for recall should be changed to 7.5 for appropriate screening outcome. On the other hand, considering the low cost of filter paper and importance of missing any case of CH, changing the cutoff point is not necessary. However, further studies in different parts of Iran are required to obtain more accurate results and consider all related factors.