POSTER PRESENTATION Open Access Neonatal screening for congenital hypothyroidism: primary thryotropin screening: comparison of false positive rate using radioimmunossay (RIA) Vs fluorometric assay (FIA) Diet S Rustama * , Elly Rosilawati, Vidi Permatagalih From 7th APPES Biennial Scientific Meeting Nusa Dua, Bali. 14-17 November 2012 Background In Indonesia one of the challenges in implementing neonatal screening for congenital hypothyroidism (CH) is early discharge of infants, therefore we could not avoid to take the specimens between 24 to 48 hours of age, resulted in high false-positive rate. Since the begining of the neonatal screening program, radioimmunoassay (RIA) was used for primary TSH screening. Fluoroimmu- noassay (FIA) are expected to be more sensitive method. Objective To compare the results of TSH measurements, using RIA and FIA in efforts to minimize false positive rate. Methods Blood-spotted filter paper specimens, obtained by heel prick for primary TSH screening were collected from neonates born in 12 hospitals in Bandung. Low birth weight infants, sick neonates, and specimens collected less than 24 ours of age were excluded. In 2008, RIA (Coat-A-Count, Neonatal TSH IRMA), and in 2009 FIA (DELFIA Neonatal hTSH) was used. The cutoff value of TSH was 20mU/L. We calculated the false positive results on specimens obtained within 24-48 hours after birth and those taken after 48 hours. The false positive rate compared within two assays. Results Specimens from 7915 babies were measured by RIA, 53.46 % were collected before 48 hours of age, 36.18% between 24 to 48 hours, and 7684 babies were measured by FIA, 61.17% were collected before 48 hours of age and 39.43% between 24 to 48 hours. Healthy, fullterm babies screened by RIA at age after 24 hours were 6525 with 0.86% recall rate and 0.83% false positive rate. Six thousands and thirteen specimens were measured by FIA, with 0.17% recall rate and 0.13% false positive rate, significantly lower than RIA (p <0.05). Using FIA recall rate and false positive rate on specimen collected between 24 to 48 hours are 0.16% and 0.16%, while on specimen collected after 48 hours are 0.17% and 0.10%, not significantly different (p=0.07). Conclusions Primary TSH screening for congenital hypothyroidism using FIA is more sensitive RIA. Lower recall rate as well as false positive rate decreased the burden of track- ing the infants for confirmatory, therefore switching the test to FIA is appropriately reasonable. Published: 3 October 2013 doi:10.1186/1687-9856-2013-S1-P151 Cite this article as: Rustama et al.: Neonatal screening for congenital hypothyroidism: primary thryotropin screening: comparison of false positive rate using radioimmunossay (RIA) Vs fluorometric assay (FIA). International Journal of Pediatric Endocrinology 2013 2013(Suppl 1):P151. Refference Centre of Neonatal Screening Faculty of Medicine, Padjadjaran University, Hasan Sadikin General Hospital, Bandung, West Java, Indonesia Rustama et al. International Journal of Pediatric Endocrinology 2013, 2013(Suppl 1):P151 http://www.ijpeonline.com/content/2013/S1/P151 © 2013 Rustama et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Neonatal screening for congenital hypothyroidism: primary thryotropin screening: comparison of false positive rate using radioimmunossay (RIA) Vs fluorometric assay (FIA)

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Page 1: Neonatal screening for congenital hypothyroidism: primary thryotropin screening: comparison of false positive rate using radioimmunossay (RIA) Vs fluorometric assay (FIA)

POSTER PRESENTATION Open Access

Neonatal screening for congenitalhypothyroidism: primary thryotropin screening:comparison of false positive rate usingradioimmunossay (RIA) Vs fluorometric assay (FIA)Diet S Rustama*, Elly Rosilawati, Vidi Permatagalih

From 7th APPES Biennial Scientific MeetingNusa Dua, Bali. 14-17 November 2012

BackgroundIn Indonesia one of the challenges in implementing neo-natal screening for congenital hypothyroidism (CH) isearly discharge of infants, therefore we could not avoid totake the specimens between 24 to 48 hours of age,resulted in high false-positive rate. Since the begining ofthe neonatal screening program, radioimmunoassay(RIA) was used for primary TSH screening. Fluoroimmu-noassay (FIA) are expected to be more sensitive method.

ObjectiveTo compare the results of TSH measurements, usingRIA and FIA in efforts to minimize false positive rate.

MethodsBlood-spotted filter paper specimens, obtained by heelprick for primary TSH screening were collected fromneonates born in 12 hospitals in Bandung. Low birthweight infants, sick neonates, and specimens collectedless than 24 ours of age were excluded. In 2008, RIA(Coat-A-Count, Neonatal TSH IRMA), and in 2009 FIA(DELFIA Neonatal hTSH) was used. The cutoff value ofTSH was 20mU/L. We calculated the false positiveresults on specimens obtained within 24-48 hours afterbirth and those taken after 48 hours. The false positiverate compared within two assays.

ResultsSpecimens from 7915 babies were measured by RIA,53.46 % were collected before 48 hours of age, 36.18%

between 24 to 48 hours, and 7684 babies were measuredby FIA, 61.17% were collected before 48 hours of ageand 39.43% between 24 to 48 hours. Healthy, fulltermbabies screened by RIA at age after 24 hours were 6525with 0.86% recall rate and 0.83% false positive rate. Sixthousands and thirteen specimens were measured byFIA, with 0.17% recall rate and 0.13% false positive rate,significantly lower than RIA (p <0.05). Using FIA recallrate and false positive rate on specimen collectedbetween 24 to 48 hours are 0.16% and 0.16%, while onspecimen collected after 48 hours are 0.17% and 0.10%,not significantly different (p=0.07).

ConclusionsPrimary TSH screening for congenital hypothyroidismusing FIA is more sensitive RIA. Lower recall rate aswell as false positive rate decreased the burden of track-ing the infants for confirmatory, therefore switching thetest to FIA is appropriately reasonable.

Published: 3 October 2013

doi:10.1186/1687-9856-2013-S1-P151Cite this article as: Rustama et al.: Neonatal screening for congenitalhypothyroidism: primary thryotropin screening: comparison of falsepositive rate using radioimmunossay (RIA) Vs fluorometric assay (FIA).International Journal of Pediatric Endocrinology 2013 2013(Suppl 1):P151.

Refference Centre of Neonatal Screening Faculty of Medicine, PadjadjaranUniversity, Hasan Sadikin General Hospital, Bandung, West Java, Indonesia

Rustama et al. International Journal of Pediatric Endocrinology 2013, 2013(Suppl 1):P151http://www.ijpeonline.com/content/2013/S1/P151

© 2013 Rustama et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the CreativeCommons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, andreproduction in any medium, provided the original work is properly cited.

http://creativecommons.org/licenses/by/2.0