Serum Thyroglobulin helps in the diagnostic confirmation of congenital hypothyroidism (CH) detected by neonatal screening

A.CHIESA,; P.PAPENDIECK,; G. BALLERINI,; G.ROPELATO,; L. GRUÑEIRO-PAPENDIECK

Rotterdam Holanda

Congreso; 45| Annual Meeting of th e European Society for Pediatric Endocinology; 2006

ESPE

Thyroglobulin, the most abundant thyroid specific protein, is a key precursor in the production of thyroid hormone. In the absence of thyroid damage the major determinants of its serum concentration are thyroid cell mass and TSH stimulation. So, it has been proposed as a tool for  ethiological diagnostic approach of congenital hypothyroidism. To assess the usefulness of serum TG measured by a  sensible method in the ethiologic evaluation of CH, TSH , T4, T3 by ECLIA, thyroid antibodies and  TG by IFMA (detection limit 0,9 ng/ml)  were determined in 63 newborns detected by screening. They were classified according to their Tc 99 thyroid scan and ultrasound in 1) ectopic (n:28)  2) athyreotic a) with coincident ultrasound (n:12) b) with discordant ultrasound (n:5) 3) eutopics a) with goiter (n:13) b) without goiter (n:5) For reference age values TG was determined in 32 normal children control aged 7 to 50 days.. Initial TG levels (ng/ml) in  CH were: 1) ectopic  Median (M): 135.5 range (r) 17.9 - 492, 2) athyreotic: a) with coincident ultrasound M:0.58 r:0.03 - 6, b) with discordant ultrasound M: 65.2 r: 13.7- 150 y 3) eutopics: a) with goiter M: 1218 r: 0.9 - 2186, b) without goiter M:98.6 r: 40.3 - 330. Control group M: 41.5, Pc3 11.5 y Pc97 99.4 Conclusion: TG was useful to evaluate CH  at the moment of diagnostic confirmation The finding of normal circulating TG levels in patients with discordant thyroid scan / ultrasound suggests a better sensitivity of TG with respect to the scan in detecting thyroid tissue. TG appears to be a useful complement in the study of CH at diagnosis allowing a better rational genetic approach  to disorders of thyroid formation and differentiation