Cord blood versus heel-stick sampling for measuring thyroid stimulating hormone for newborn screening of congenital hypothyroidism

Abstract

BACKGROUND: Screening for congenital hypothyroidism (CH) using cord blood or heel-stick samples is considered essential for the prevention of long-term complications CH, which include intellectual disability and slow growth.OBJECTIVE: Compare the sensitivity and specificity of cord blood and heel-stick samples for determining thyroid-stimulating hormone (TSH) levels for the detection of CH.DESIGN: Comparative diagnostic accuracy.SETTINGS: Tertiary care center in Riyadh.PATIENTS AND METHODS: The study included all infants who were delivered during the period from May 2011 to May 2013. As part of routine newborn screening, both cord blood and heel-stick samples were collected from each newborn for CH screening by measuring TSH levels. A cord TSH level was considered positive if the concentration of TSH was more than 60 mIU/L and negative if less than 30 mIU/L. Any cord TSH level between 30-60 mIU/L was considered borderline, and free T4 was measured from the same cord sample. The result was considered positive if the free T4 level was below 9 pmol/L. Heel-stick TSH levels more than 20 µU/L were considered positive. All newborns with positive results were recalled and a peripheral venous sample was taken for TSH and free T4 for confirmation.MAIN OUTCOME MEASURES: Sensitivity and specificity, positive and negative predictive values and recall rates.SAMPLE SIZE: 17 729 screened babies.RESULTS: Of 17 729 neonates screened, 7 were diagnosed as having primary CH. All confirmed cases were detected by both cord and heel-stick TSH levels: 88 cord results were positive (sensitivity 100%, specificity 99.6%, with a recall rate of 0.04%) and 305 heel-stick results were positive (sensitivity 100%, specificity 98.3%, with a recall rate of 1.68%).CONCLUSION: Both cord and heel-stick TSH testing detected all cases of CH. Cord testing was superior to heel-stick testing as the recall rate was lower. We think cord TSH testing is preferable when heel-stick is difficult or early discharge is the practice.LIMITATIONS: Retrospective; the timing of newborn screening for TSH sampling was premature.CONFLICT OF INTEREST: None.

Diagnostic comparison between cord blood and filter paper for the screening of congenital hypothyroidism

“…In terms of sensitivity and specificity, 139 neonates had positive heel‐prick TSH samples with 100% sensitivity and 99.3% specificity. Similarly, Al‐Juraibah et al had 305 positive heel‐prick TSH samples with 100% sensitivity, 98.3% specificity but higher recall rate of 1.68% compared to 0.6% and less positive predictive value of 2.3 compared to 8.63% in our study 5 . On the contrary, our cord‐blood TSH samples results with 75% sensitivity and 99.9% specificity were compared with the result in Al‐Juraibah et al study with 88 positive samples with 100% sensitivity and 99.6% specificity but similar positive predictive values of 8.63% and 7.95%, respectively, and much lower recall rate 5 .…”

“…Similarly, Al‐Juraibah et al had 305 positive heel‐prick TSH samples with 100% sensitivity, 98.3% specificity but higher recall rate of 1.68% compared to 0.6% and less positive predictive value of 2.3 compared to 8.63% in our study 5 . On the contrary, our cord‐blood TSH samples results with 75% sensitivity and 99.9% specificity were compared with the result in Al‐Juraibah et al study with 88 positive samples with 100% sensitivity and 99.6% specificity but similar positive predictive values of 8.63% and 7.95%, respectively, and much lower recall rate 5 . Though Al‐Juraibah et al had highly sensitive results, they did not investigate preterm babies who had late TSH rise, which can be simply missed.…”

“…Our study had a lower recall rate than different studies 5,10,11 . This was attributed to many reasons such as sample size variation, cutoff values either 20 or 30 mIU/L, TSH analytical methods, and sample collection time.…”

“…Our data demonstrated that cord TSH results had fewer false‐positive samples compared with heel prick. Al‐Juraibah et al reported that false‐positive rates were around three times higher in heel‐prick TSH compared with cord blood 5 . This supports that heel‐prick TSH is inferior to cord TSH regarding positive predictive value.…”

Effect analysis of embracing breast milk sucking to relieve pain of neonatal heel blood sampling: a randomized controlled trial

“…When heel blood sampling is carried out, painful stimulation will cause them to cry and twist their bodies, making it difficult to successfully complete blood collection. At the same time, painful stimulation with too frequency and too long time are likely to cause the newborns to experience sleep quality, decreased appetite, or immune function, and affect their normal development (14,15). Newborns are unable to communicate effectively.…”