Abstract Ref Number = APCP27
Implementation of Guideline for Congenital Hypothyroidism Screening in Daily Practice
Newborn screening Task Force, Indonesian Pediatrics Society
Pediatric Endocrinology Division, Department of Child Health
Universitas IndonesiaCipto Mangunkusumo General Hospital, Jakarta, Indonesia
Congenital hypothyroidism (CH) is the most common cause of preventable intellectual disability. The incidence of CH is higher in Asian and Hispanic populations. It is also higher in preterm compared to term infants.
Clinical features of CH are often subtle and many infants remain undiagnosed at birth. Although clinical features of CH may be subtle at birth, jaundice, umbilical hernia, macroglossia and constipation become progressively apparent 2-6 weeks post partum. The infant brain requires thyroid hormone (T4). Without T4, there is irreversible loss of 5 IQ points/week, resulting in permanent intellectual deficit. The best way to detect CH and avoid irreversible insult to the infant brain is by newborn screening (NBS).
Since its introduction in the mid-1970s, NBS programs for CH have been highly successful and economically beneficial worldwide. In countries where newborn screening programs take place, all infants with CH are diagnosed. However, only 25% of infants worldwide are screened. For 75% infants, especially in developing countries, CH is diagnosed based on clinical suspicion. Not all health professionals are aware of the subtle or even overt clinical symptoms and signs of CH, further delaying diagnosis. Thus, the infants already have irreversible brain injury resulting lower cognitive function.
A national guideline for CH newborn screening (NBS) program in Indonesia was only introduced in 2014.Implementation of newborn screening remains sporadic, with only around 2-4% of newborns screened. Problems to be resolved are different screening methods and variable interpretation, together with clinical unfamiliarity with the NBS program. Consequently, high rates of false positive or false negative diagnosis of CH is possible.
TSH is the most sensitive test for detecting primary CH. Indonesian guidelines recommend measurement of TSH collected in a dried blood spot 48-72 hours after birth. A confirmatory test should be performed immediately in infants with TSH level > 20 IU/mL. Failure to comply with this recommendation results in either false positive that leads to over diagnosis of CH or false negative that leads to delayed diagnosis. For preterm infants with GA <37 weeks, low birth weight (LBW) and very LBW, ill neonates admitted to NICU, and infants from whom a specimen is collected within the first 24 hours of life, interpretation of newborn screening is complex and requires specialist advice.
Diagnosis of CH in infants detected by NS should be performed under supervision of a pediatric endocrinologist. Treatment should be commenced immediately after diagnosis without any delay. Imaging studies of thyroid ultrasound and/or scintigraphy aid diagnosis but should never be allowed to delay treatment. Cases of newborn screening results and their interpretation will be presented to aid in evaluation of newborn screening in clinical settings.
Keywords: congenital hypothyroidism, newborn screening