High recall rate in the screening program for congenital hypothyroidism in Rafsanjan

Congenital hypothyroidism (CH) is one of the most common preventable causes of mental retardation in newborns. In this study, we investigated the incidence of CH in Rafsanjan. From all neonates born from 22 Dec 2001 to 22 Apr 2002, heel blood samples on filter paper were collected and TSH values were assayed using ELISA method and TSH 20 mIU/L was considered abnormal and recalled. Upon recall, the diagnosis of CH was confirmed according to abnormal serum TSH levels using age-adjusted reference values for thyrotropin. TSH < 3.98 mIU/L was considered normal according to the manufacturer's instructions. The association between heel-blood TSH values and of birth weight and height, sex, maternal age, gestational age, delivery mode, maternal occupational status, parental educational level, thyroid disorders in family, and iodized salt consumption were assessed. Of 950 neonates (480 girls and 470 boys), 230 (24.2%) had TSH 20 mIU/L. TSH levels were between 20-49.9 and  50 mIU/L in 206 and 24 neonates, respectively. Of total recalled neonates, only 152 came for serum confirmatory tests between 1-4 months of age. Nine cases had serum TSH  3.98 mIU/L but none of them had enough elevated TSH values to confirm the diagnosis of CH. The only neonate with heel-blood TSH of 137 mIU/L was inaccessible and the CH diagnosis remained unclear. No association was found between heel-blood and serum TSH and of the variables mentioned above. The incidence of CH in Rafsanjan remains unclear however, the recall rate was extremely high. The latter is not only suggestive of a high prevalence of CH, but also of some etiologic factors affecting the rate of hyperthyrotropinemia in Rafsanjan.