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Objective: In Iran thyroid-stimulating hormone (TSH) based neonatal screening program is included in health care services from 2005 for detection of patients with primary congenital hypothyroidism (CH). This study was performed for a critical evaluation of the screening program primary congenital hypothyroidism in Fars province, Iran. Methods: From November 2006 to September 2007, TSH serum concentrations of 63031 newborns, 3 to 5 days old born in Fars province, were measured by heel prick. The newborns with TSH ≥5mIU/L were recalled for measurement of serumT4 and TSH in venous blood samples Findings: Of 127 recalled subjects, 43 were confirmed to be hypothyroid, showing a prevalence of 1:1465 with F:M ratio of 1.05:1. The most common clinical and radiological findings were prolonged jaundice (73%), large anterior fontanel (56%), wide posterior fontanel (55%), absence of distal femoral epiphysis (20%), and umbilical hernia (11%). Scintigraphy of the thyroid with 99mTC revealed eutopia (67.4%), hypoplasia (23.3%), agenesis (4.7%) and ectopia (2.3%). Conclusion: It is concluded that a cut off value of TSH≥5mIU/L overestimates recalling the number of patients with CH. The most common cause of congenital hypothyroidism is not dysgenesis of the gland and perhaps dyshormonogenesis in Iran is more common than what is reported in other countries. [ABSTRACT FROM AUTHOR]

Objective: To determine the prevalence of congenital hypothyroidism (CH), permanent and transient CH. Methods: From November 2006 to September 2007, 63031 newborns were screened by measuring serum TSH obtained by heel prick. The neonates who had a TSH≥5mU/L were recalled for measurement of serum T4, thyroid stimulating hormone (TSH) and TSH receptor blocking antibodies (TRBAb) in venous samples. In 43 primarily diagnosed as cases of CH, treatment was discontinued at age 2-3 years for 4 weeks and T4 and TSH were measured again. Permanent or transient CH was determined from the results of these tests and radiologic evaluation. Findings: The incidence of congenital hypothyroidism was found to be 1:1465 with a female to male ratio of 1.19:1. The most common clinical findings were prolonged jaundice (73%), large anterior fontanel (56%) and wide posterior fontanel (55%). In 43 patients with CH, prevalence of permanent and transient form of the disorder was 53.6% and 46.4% respectively. Permanent CH was associated with higher initial TSH level than transient hypothyroidism (P<0.001). The most common etiology of permanent CH was dyshormonogenesis (57%). TRBAb was found in 6.8% of the total 43 cases. Conclusion: Congenital hypothyroidism in Iran may have different etiologies. Due to higher rate of transient CH than other similar researches, it is reasonable to follow these patients for a longer period to rule out the possibility of permanent hypothyroidism. _H [ABSTRACT FROM AUTHOR]

Introduction: A large number of congenital hypothyroidism (CH) cases in Iran are transient. This study was designed to investigate the aetiology of permanent CH (PCH) by thyroid scintigraphy (TS) and its relationship with the first diagnostic thyrotropin (TSH)., Material and Methods: During 12 years (2005-2017) of CH screening in southwest Iran, all infants referred with the diagnosis of CH were followed until their third birthday, when they were re-evaluated for serum T4, TSH after discontinuing the treatment for 3-4 weeks. If the last test indicated a PCH state (TSH >10 mU/L with any levels of T4), TS was performed, and, based on the results, the patients were categorised as agenesis, dysgenesis (sublingual, thyroglossal cyst), and normal/diffuse goitre (indicating dyshormonogenesis)., Results: After excluding all transient CH subjects, 224 permanent CH cases were enrolled (52.7% female). Seasonal distributions were as follows: spring: 25.7%, summer: 27.9%, autumn: 20.3%, and winter: 26.1%. No significant differences were found between females and males and the different modes of delivery (55.4% were delivered by caesarean section) regarding T4, TSH (p > 0.05). Of a total of 213 performed scans, 20.7% had agenesis, 36.2% had dysgenesis, and 43.2% were normal or goitrous. Those with agenesis/dysgenetic thyroid had a lower T4 and a higher TSH than those with normal scans. However, the differences were not significant. Compared to those who had TSH < 40 mU/L, patients with TSH ≥ 40mU/L had 46% (95% CI: 1.06-2.02) more risk of agenesis or dysgenesis in TS., Conclusions: More than 40% of PCH are caused by dyshormonogenesis in Iran. Having a TSH ≥ 40 mU/L after the first week of life significantly raises the probability of thyroid agenesis/dysgenesis as the cause.