# Neonatal screening for congenital hypothyroidism: 28-year experience in the state of Minas Gerais, Brazil

## TL;DR

This study summarizes 28 years of a neonatal screening program in Brazil for congenital hypothyroidism, showing stable incidence and improved screening and treatment timelines.

## Contribution

A detailed 28-year analysis of a public health neonatal screening program for congenital hypothyroidism in Minas Gerais, Brazil.

## Key findings

- The incidence of congenital hypothyroidism remained stable at 1:3,298 live births over 28 years.
- Median age at sample collection and treatment initiation significantly decreased over time.
- Thyroid dysgenesis was the most common cause of permanent congenital hypothyroidism.

## Abstract

The objective of this study was to determine the incidence of congenital hypothyroidism (CH) in Minas Gerais, Brazil, and evaluate the development of the Minas Gerais Neonatal Screening Program (PTN-MG) over the past 30 years.

This was a retrospective longitudinal cohort study since the implementation of neonatal screening for CH, in 1994. Bloodspots on filter paper are collected, between the third and fifth day of life, at primary healthcare units, with a TSH threshold of 10 mIU/L. The identification of an abnormal result triggers an active search for the child to confirm the diagnosis. The incidence of CH and its variation over the years, the percentage of permanent cases, and the age at sample collection and treatment initiation were analyzed.

The incidence of CH was 1:3,298 live births among 6,864,719 newborns screened, with no trend of change over the years (p = 0.08). The median age at sample collection decreased from 11 to 5 days (p < 0.01) and at treatment initiation from 88 to 16 days (p < 0.01). Among the confirmed patients, 77 % had permanent CH, thyroid dysgenesis accounted for 43.6 % of cases, gland-in-situ for 56.3 %.

The incidence of CH has remained stable in Minas Gerais over the past 28 years. The PTN-MG is a public health program with an active monitoring and control sector that has shown significant improvements in its indicators since its implementation. The experience of the program has shown that rigorous monitoring and follow-up of infants have been an essential strategy for achieving satisfactory results.