high prevalence of severe congenital hypothyroidism: a necessity for an effective strategy of detection and treatment in the national screening program for neonatal hypothyroidism

ABSTRACT

The high prevalence of congenital hypothyroidism [CH] has been reported previously, however the severity of CH has not been evaluated yet. This report illustrates the severity of CH in Tehran and Damavand.From February 1998 to May 2003, 31 hypothyroid neonates [>37 weeks gestation] were detected during the CH screening program in Tehran and Damavand. Neonates were grouped in permanent [n=25] and transient CH [n=6]. Those in the permanent CH were assigned in Dysgenetic [n=18] and dyshormonogenetic [n=5] groups. Dysgenetic cases were further classified in ectopic-hypoplastic [n=13] and athyroitic [n=5] cases. Serum thyroxine values and frequency distribution of sever hypothyroidism [T4<42.8nmol/L] were compared among the groups.Mean [ +/- SD] of T4 of permanent CH [38.0 +/- 42.2 nmol/l] was significantly lower than transient CH [101.9 +/- 46.5 nmol/l] [p < 0.01]. It was similar in dysgenetic [41.9 +/- 47.5 nmol/l] and dyshormonogenetic [27.8 +/- 23.7 nmol/l]. Both latter groups shoed significantly lower T4 values than transient CH [p < 0.05]. Athyreotic cases [11.1 +/- 5.9 nmol/l] had lower T4 levels than transient CH [p < 0.05]. Severe CH was present in 18[72%] permanent, 1[16.7%] transient, 8[61.5%] ectopic-hypoplastic, 5[100%] athyroitic, and 5[71.4%] dyshormonogenetic CH cases. Odds ratio of severe CH occurrence in permanent CH as compared to transient CH was 12.9[95% CI 1.27-130.54].The high prevalence of severe CH warrants an effective national CH screening program for early detection of CH cases and sufficient replacement therapy