Geographical epidemiology of neonatal transitory hypothyroidism. Trend evidence in central Italian region.

AIM: To study the geographical distribution of high thyroid-stimulating hormone (TSH) level in the Marche region (central Italy). METHODS: Data were drawn from the Register of Neonatal Screening for Congenital Hypothyroidism (CH) of the Marche region (Italy), located at the Child Neuropsychiatry Department of Civil Hospital in Fano (Marche, Italy). Data were analyzed by Ohno's method. RESULTS: The findings of this study show a nonuniform distribution of high TSH levels in the Marche region, with an evident gradient from North to South. CONCLUSIONS: It is not possible to provide a definitive interpretation of these findings, although the specialized literature suggests that a high level of TSH in neonates should be interpreted as a marker of insufficient iodine uptake. Other factors affecting TSH level are also taken into consideration.

Risk factors for congenital hypothyroidism: results of a population case-control study (1997-2003).

OBJECTIVE: To identify risk factors for permanent and transient congenital hypothyroidism (CH). DESIGN: A population-based case-control study was carried out by using the network created in Italy for the National Register of Infants with CH. METHODS: Four controls were enrolled for each new CH infant; 173 cases and 690 controls were enrolled in 4 years. In order to distinguish among risk factors for permanent and transient CH, diagnosis was re-evaluated 3 years after enrollment when there was a suspicion of transient CH being present. Familial, maternal, neonatal and environmental influences were investigated. RESULTS: An increased risk for permanent CH was detected in twins by a multivariate analysis (odds ratio (OR) = 12.2, 95% confidence interval (CI): 2.4-62.3). A statistically significant association with additional birth defects, female gender and gestational age >40 weeks was also confirmed. Although not significant, an increased risk of CH was observed among infants with a family history of thyroid diseases among parents (OR = 1.9, 95% CI: 0.7-5.2). Maternal diabetes was also found to be slightly associated with permanent CH (OR = 15.7, 95% CI: 0.9-523) in infants who were large for gestational age. With regard to transient CH, intrauterine growth retardation and preterm delivery were independent risk factors for this form of CH. CONCLUSION: This study showed that many risk factors contribute to the aetiology of CH. In particular, our results suggested a multifactorial origin of CH in which genetic and environmental factors play a role in the development of the disease.