The changing epidemiology of congenital hypothyroidism: fact or artifact?

Abstract

Screening increases prevalence estimates for most diseases and congenital hypothyroidism (CH) is no exception, affecting one in 6700 children by clinical ascertainment and one in 3500 in the first surveys of systematic biochemical screening of newborns. Importantly, screening has resulted in the disappearance of intellectual disability due to CH. A further doubling in prevalence estimates has recently been reported, mostly accounted for by changes in screening algorithms; accordingly, the prevalence of overt CH has remained stable. Population-based registries that distinguish confirmed diagnoses from positive screening results have proved invaluable. These registries should include: etiology of CH based on imaging, ideally technetium scintigraphy; ethnicity; socio-educational data; input from the screening laboratories and pediatric endocrinologists. Efforts should now be directed at increasing the proportion of the world's newborns screened for overt CH (currently 30%) and at determining if neonates with mild hyperthyrotropinemia also benefit from early treatment.

Congenital Hypothyroidism in Neonates of a Tertiary Care Hospital

“… 5 Now this range stands at 1:4000 after congenital screening programs were instituted. 6 In developing countries, newborn screening (NS) is mandatory. However in countries like Pakistan no Newborn Screening program has been started yet.…”

A systematic review of the outcomes of false‐positive results on newborn screening for congenital hypothyroidism

“…5,6 The ratio of FPs to true positives for CH is estimated at 15:1, 7 with global recall rates ranging from 0.01% to 13.3%. 1 Whether lowering of TSH thresholds identifies additional cases of CH that will benefit from treatment, or rather primarily increases screening costs, detection of transient, mild or subclinical hypothyroidism, 5,8,9 or clinically insignificant 'disease', 3 has long been disputed. Alm et al 10 retrospectively tested 100,239 stored blood spots collected in Sweden during the 1970s, before the initiation of screening for CH, then followed up the records of 31 of 32 infants with TSH > 20 mU/L whole blood.…”

Delayed Diagnosis of Congenital Hypothyroidism in a 6-month-old Male Infant in Tamale, Ghana.

“…3,4 There has been an increase in the reported prevalence of congenital hypothyroidism because of the improvements in neonatal medicine and inborn screening programs, as well as the increased sensitivity of testing methods. 3,5 Deladoëy et al reported an increase from 1 in 6700 children to 1 in 3500 children in their review regarding the condition, worldwide. 5 In Africa, studies in Nigeria have shown varying incidence between 16.4% and 1.4%.…”

“…3,5 Deladoëy et al reported an increase from 1 in 6700 children to 1 in 3500 children in their review regarding the condition, worldwide. 5 In Africa, studies in Nigeria have shown varying incidence between 16.4% and 1.4%. 6,7 However, a lower incidence (0.1%) was reported in South Africa.…”