High prevalence of congenital hypothyroidism in the Greek Cypriot population: results of the neonatal screening program 1990-2000

Abstract

Objective: To evaluate the results of the screening program for congenital hypothyroidism (CH) in the Greek Cypriot population.

Children and methods: During 1990-2000, 109,532 neonates were screened by TSH determination. Permanent CH was proven with biochemical findings after discontinuation of treatment for scintigraphy at the age of 3 years.

Results: Permanent CH was diagnosed in 61 infants, incidence 1/1800, with female/male ratio 2.05/1. The most common clinical findings were omphalocele (61%), large anterior fontanelles (49%) and edema of the eyelids (34%). The more delayed the bone maturation, the lower were initial T4 levels (p = 0.005). Bone maturation tended to be more advanced in thyroid hypoplasia and more delayed in thyroid agenesis (p = 0.049). Scintigraphy of the thyroid with TC99 revealed ectopia in 38%, thyroid agenesis in 36%, thyroid hypoplasia in 24% and dyshormonogenesis in 1.7%. Children with transient CH had significantly lower T4 and higher TSH values initially compared to those with permanent CH after birth; initial TSH level, however, failed to predict the nature of CH. Children with transient CH required less thyroxine dosage to maintain normal thyroid hormone levels and they had a normal thyroid gland on scintigraphy. The TSH level was normalized before the age of 2 months with a starting L-thyroxine dose of 10 microg/kg/daily.

Conclusions: The incidence of primary CH in Greek Cypriots is 1/1800 live births. The most common etiology is thyroid dysgenesis. Initial T4 levels correlated with the degree of skeletal maturation and the etiology. Initial TSH level, although lower in children with transient CH, could not predict the nature of CH.