Prevalence of Congenital Hypothyroidism and Transient Increased Levels of TSH in Yazd Province

Congenital hypothyroidism is one of the most preventable causes of mental retardation. Worldwide, incidences vary from 1:3000 to 1:4000 and mean incidence in Iran is estimated to be 1:1000. Neonatal screening and early treatment within first 2 weeks of neonatal period can prevent neurocognitive deficits. We aimed to study the incidence of CH and increased levels of TSH in Yazd province and collect data describing the disease status and designing first and second levels of preventive interventions.

This descriptive analytic study was performed by census cross sectional method on 13022 neonates in Yazd province in 2006-2007(March 2006- March 2007) including 6495 females and 6527 males. Sampling was done (within the first 3-5 days of life) by lancet sticking of neonatal heel. After transfer of 3 blood drops over filter papers, the TSH level was measured. If the TSH level was equal or higher than 5 mu/l, additional confirmation tests were done. Neonates were diagnosed according to serum confirmation test (TSH10 mu/l or T4<6.5g/dl) and underwent treatment according to national guidelines. Data was analyzed by SPSS software.

Total number of patients was 45, including 25 males (55.5%) and 20 females (44.5%). Prevalence in males, females and overall was consecutively, 1:261, 1:325 and 1:289, but this difference was not statistically significant. Prevalence in urban and rural areas was 1:315 and 1:216, but the difference was statistically not significant. The prevalence during spring, summer, autumn& winter was 1:95, 1:250, 1:1934 and 1:369, respectively, that was statistically significant. Mean age at sampling was 7.2 days, mean TSH level 2.3 mu/l and mean age of mothers was 25.8 years.

Incidence of CH and transient increased levels of TSH in Yazd province is significantly higher than national and worldwide levels that necessitate the constancy and reinforcement of neonatal screening program. On the other hand, complementary studies for recognizing relevant factors, particularly iodine deficiency are one of the priorities of health system research in Yazd.