High Incidence and Recall Rate of Congenital Hypothyroidism in Zanjan Province, a Health Problem or a Study Challenge?

Background: In Iran, congenital hypothyroidism (CH) screening programs to prevent mental retardation have been started recently. In this national program, all neonates with thyroid-stimulating hormone (TSH) level ≥ 5mIU/L are required to be recalled for a confirmatory test (venous sampling).
Objectives: This study was designed to investigate the incidence of CH and the patient recall rate on the basis of the above mentioned cutoff value for TSH and to compare the results with those obtained in other studies.
Patients and Methods: According to the screening protocol for CH, we assessed neonates born from February 2007 to January 2008 and registered details on the birth date, sex, birth weight, maternal gestational age, and parental consanguinity. TSH was measured from heel-prick blood samples obtained from neonates aged between 3 and 7 days. Neonates showing a TSH level of ≥ 5mIU/L were recalled for undergoing confirmatory tests.
Results: Among 18008 neonates screened for CH, 730 (4.1%) were recalled (TSH, ≥ 5mIU/L). Out of the recalled neonates, 96% were full-term neonates with a mean age of 5.0 ± 3.2 days and a mean TSH level of 8.6 ± 11.4mIU/L. CH was detected in 20 (2.7%) recalled neonates (incidence ratio of 1 in 895 live births) and subclinical hypothyroidism in 45 (6.1%) recalled neonates (incidence ratio of 1 in 398 live births).
Conclusions: Investigations have shown that Asian and Iranian neonates show a high CH prevalence. The recall rate in our study on the basis of the TSH cutoff value of more than 5mIU/L was higher (4%) than that in other studies. Therefore, in addition to emphasizing the importance of neonatal screening, we suggest that the cutoff level of TSH in the national screening program be reassessed and revised to reduce the recall rate for neonates.

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