Birth prevalence of congenital hypothyroidism in Mexico

• Published in: Paediatric and perinatal epidemiology Vol. 22; no. 5; pp. 478 - 485
• Main Authors: Rendón-Macías, Mario E., Morales-García, Inés, Huerta-Hernández, Emilio, Silva-Batalla, Anabel, Villasís-Keever, Miguel A.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-09-2008
• Subjects: birth prevalence; congenital hypothyroidism; Congenital Hypothyroidism - diagnosis; Congenital Hypothyroidism - epidemiology; Humans; Infant, Newborn; Mexico - epidemiology; neonatal screening; Neonatal Screening - methods; Predictive Value of Tests; Prospective Studies; Statistics as Topic; Thyrotropin - analysis; Thyrotropin - blood; Mexico
• ISSN: 0269-5022; 1365-3016
• DOI: 10.1111/j.1365-3016.2008.00955.x

Summary
The Mexican Institute of Social Security (IMSS) provides care for more than 40% of the Mexican population. This report constitutes the first study of the incidence of congenital hypothyroidism (CH) in Mexican children. We performed a prospective study with a population base. CH screening began in 1997 with blood samples from the heel taken 72 h after birth; from 2000, the detection strategy was changed nationwide and blood samples were taken from the umbilical cord in all newborns for determination of thyroid‐stimulating hormone (TSH) concentration. We evaluated the annual coverage. TSH concentration was measured by chemoluminescence; TSH values ≥30 µIU/mL in umbilical cord blood and 15 µIU/mL in capillary blood were considered positive cases and were confirmed through hormonal studies. The incidence and 95% confidence intervals [95% CI] were calculated.
We found that coverage within the IMSS population was 53% from 1997 to 2000 and had increased to 95% by 2001. A total of 2 777 292 children from 2 975 157 births (93%) were studied between 2000 and 2004. Of these, 4050 had a high TSH concentration leading to suspicion of CH; CH was confirmed in 1286 (32%). The resulting incidence was 4.3/10 000 livebirths [95% CI 3.6, 5.1]. With the results obtained, we conclude that the IMSS strategy of CH screening at birth ensured 95% coverage of children in the system. The birth prevalence of CH reported is among the highest in the world.