Objective: In Romania, congenital hypothyroidism screening is performed by measuring thyroid-stimulating-hormone levels from dried blood samples. If the initial value is above the recommended cut-off value (10 mUI/L), the newborn is recalled for a second blood collection. The aim of this study was to investigate and report potential improvements on the screening protocol that is currently applied in our country in order to reduce the time between birth and treatment initiation in newborns positive to congenital hypothyroidism screening.
Methods: Blood samples were collected from 41 full-term newborns between February and March 2019 at the maternity ward from Targu Mures Emergency County Hospital. Thyroid-stimulating-hormone values were measured with a chemiluminescent microparticle immunoassay in serum samples from cord blood collected at birth, and with a fluorometric enzyme-linked immunoassay in dried blood spots collected at day 3-5 after birth. To obtain whole blood values, serum values were transformed using a formula supplied by the kit manufacturer. Calculated cord blood values were compared with dried blood spots values using the Wilcoxon test.
Results: After serum-to-whole-blood conversion,  cord blood values ranged from 2.58 to 3.66 mUI/L (95% CI). Dried blood spot values ranged from 6.70 to 7.50 mUI/L (95% CI). The Wilcoxon test p value between cord blood and dried blood spots thyroid-stimulating-hormone levels was statistically significant (p<0.01).
Conclusions: Thyroid-stimulating-hormone levels above the cut-off value were flagged by both techniques. An improvement to the existing protocol is proposed that may reduce time from positive screening results to confirmation of congenital hypothyroidism and treatment initiation.