Permanent and Transient Congenital Hypothyroidism in Fayoum, Egypt: A Descriptive Retrospective Study

Abstract

BackgroundCongenital hypothyroidism (CH) is one of the most common preventable causes of mental retardation. One important challenge in understanding the epidemiology of CH is that some newborns will have transient CH, a temporary depression of thyroid hormone concentrations that can last from several days to several months. Studies from other countries have reported that 10 to 15% of children treated for CH ultimately prove not to need treatment past 3 years of age to maintain normal hormone concentrations, and thus have transient hypothyroidism. The purpose of this study was to determine the prevalence of permanent and transient congenital hypothyroidism in Fayoum, Egypt.MethodsCases detected by Fayoum neonatal screening program (NSP) between January 2003 and December 2011, and followed up at health insurance center were included. Permanent or transient CH was determined using results of thyroid function tests.ResultsOf the 248 patients diagnosed primarily with CH by NSP; 204 (82.3%) patients were diagnosed to have permanent CH (prevalence 1/3587 live birth), and 44 (17.7%) patients were diagnosed to have transient CH (prevalence 1/16667 live birth). Initial TSH levels were higher in permanent CH cases than transient cases (p<0.004). Female to male ratio was 0.8 and 0.7 in permanent and transient CH respectively. 161 (65%) patients had thyroid dysgenesis (107 ectopic thyroid gland, 28 athyreosis and 26 thyroid hypoplasia). 87 (35%) patients had intact gland in thyroid scan and were considered to have dyshormonogenesis. Of these 87 patients 44 proved to have transient CH and 43 had permanent CH.ConclusionThe preliminary data from our study revealed that the incidences of CH as well as the permanent form were similar to worldwide reports. Although the high incidence of transient CH in our study could be explained by iodine deficiency further studies are needed to confirm the etiology and plan the treatment strategies.

Permanent and Transient Congenital Hypothyroidism in Hamadan West Province of Iran

“…Our findings on the high frequency of transient hypothyroidism are also consistent with those of Hashemipour et al, Dorrea and Ordookhani et al (16, 23, 24). Nevertheless, our findings are not in agreement with the results from other countries which have reported that 10 to 15% of children treated for CH ultimately have transient hypothyroidism (8, 20, 22). In alignment with previous studies carried out in Iran (17, 25-28), we assume that the high frequency of transient CH in Iran may be due to iodine deficiency or overload, although Iran is no longer recognized as an iodine deficient area.…”

“…Since the most common etiology of CH was dyshormonogenesis as indicated in the studies conducted by Hashemipour et al (9) and Karamizadeh et al (19) in Iran, a relatively high rate of parental consanguinity (25%) among infant with congenital hypothyroidism could account for the increased incidence of CH in our region. In support of the previous data, we also propose that the inclusion of infants of transient hypothyroidism increased the reported incidence rate of CH (8, 20). However, the effects of genetic background, autoimmune and environmental factors cannot be omitted.…”

“…Whereas, the transient type of the disease is less likely to be observed, attributed to the trans placental passage of maternal anti-thyroidal medication, Trans placental passage of a maternal thyrotropin receptor blocking antibody (TRB-Ab), gene mutation (heterozygote nonsense DUOX2 mutations), iodine deficiency or excess and immaturity of thyroidal iodine organification (4-6). The very low birth weight (< 1500 gm) and premature (< 37 weeks gestation) infants are especially at risk of hypothyroidism due to iodine deficiency (7, 8). …”

Transient hypothyroidism in the newborn: to treat or not to treat

“…In Korea, a total of 13 laboratories perform the NBS TSH, and the cutoff levels of TSH vary from 10.0 to 22.5 mIU/mL according to each laboratory protocol (8). Another recent study from Korea showed that nearly 80% of preterm infants with CH treated for 3 years with thyroxine were later diagnosed with transient hypothyroidism (9 (11). Infants with trisomy 21 (Down syndrome) have a higher incidence of hypothyroidism detected by NBS programs, occurring as commonly as 1:50 newborns but they rarely have transient hypothyroidism (12).…”

Higher Incidence Rates of Hypothyroidism and Late TSH Rise in Preterm Very-Low-Birth-Weight Infants at a Tertiary Care Center

“…Data from another large screening program in Lebanon report a prevalence of 1: 1,700 [27]. These rates are comparable to those reported from the United Arab Emirates (1: 1,873) [28], and from the Greek Cypriot population (1: 1,800) [29] but higher than some of the reported rates from Turkey (1: 2,326) [22], Egypt (1: 3,587) [23], and from different regions in Saudi Arabia (1: 2,759 [24] and 1: 4,208 [25]). Nevertheless, this apparently higher rate in the overall incidence of congenital hypothyroidism in Lebanon does not explain the magnitude of the increase in the rates detected in our population of VLBW infants.…”