Background: Congenital hypothyroidism (CH) is the most common cause of preventable mental retardation in children, thus screening programs of CH have been established for better management of the disorder and preventing its related neurodevelopmental consequences. Evidences from different screening programs indicated that the rate of CH is higher in pre-term and low birth weight newborns than normal ones due to the incomplete development of hypothalamicpituitary axis in this group of neonates. Hence, there is a great need for a practicable systematic screening method for proper diagnosis of CH in this group of neonates.
Methods: In this review, we systematically reviewed papers with the following key words([Congenital Hypothroidisn AND Screening AND Thyroxine AND Thyroid Stimulating Hormone AND low birth weight AND Premature]) in international electronic databases including PubMed, Scopus, and Google Scholar. After quality assessment of selected documents, data of finally included papers were extracted.
Results: In this review, 1452 papers (PubMed: 617; Scopus: 714; Google scholar: 121) were identified through electronic database search.194 articles assessed for eligibility,from which 36 qualified articles were selected for final evaluation. From reviewed articles 38.9%, 11.11% and 8.3% recommended rescreening in this group of neonates, lowering screening cutoff of TSH and using cutoffs according to the gestational age, respectively. Some of them (13.9%) recommended for using both TSH and T$ for screening of preterm infants. According to the reviewed papers, TSH level >10 mU/L in 2nd week of birth is diagnostically meaningful and TSH level of 1015 mU/L suggests hypothyroidism with delayed TSH rise.
Conclusion: After reviewing available data,we recommend repeating the screening test in pre-term, low birth weight and very low birth weight infants in age of two, six and ten weeks by measuring TSH and FT4 levels simultaneously and considering TSH=10 mU/L as the cutoff level for positive and suspicious cases.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology