Aims: To determine the factors which influence the suppression of thyroid-stimulating hormone (TSH) in infants with congenital hypothyroidism (CH) following treatment. Methods: We examined retrospectively the patterns of thyroid function tests from diagnosis to 3 years of age in 140 infants diagnosed with CH from screening. Patients were classified into 3 groups: athyreosis, ectopia and presumed dyshormonogenesis on the basis of thyroid scans. Adequate TSH suppression was defined as plasma TSH concentration <6 mU/l. The factors affecting the suppression of TSH at 6 months and 1 year of age which were evaluated were: initial confirmatory plasma TSH, initial plasma thyroxine (T4), mean age of starting treatment with L-T4, dose of L-T4 at diagnosis, 6 weeks, 3 months and 6 months, and aetiology of the congenital hypothyroidism. Variables were then entered in a stepwise logistic regression model for TSH suppression at 6 months and 1 year of age. Results: All infants had radionuclide scans prior to treatment: athyreosis (n = 39), ectopia (n = 78) and dyshormonogenesis (n = 23). 58% of patients had persistently raised TSH at 6 months of age while 31% of patients had a persistently raised TSH at 1 year of age. There was a significant delay in the normalisation of plasma TSH in athyreosis and ectopia groups compared with dyshormonogenesis. Multiple regression analysis for TSH suppression at 6 months of age found plasma T4 levels and aetiology of CH as independent factors affecting the timing of TSH suppression. Aetiology of CH was the only independent factor affecting TSH suppression at 1 year of age. Conclusion: At 6 months of age, plasma T4 levels at 6 weeks and 3 months, and aetiology of CH were independent factors affecting timing of TSH suppression. However, by 1 year of age, the aetiology of CH was the only independent factor affecting suppression of TSH.

American Academy of Pediatrics: Newborn screening for congenital hypothyroidism: Recommended guidelines. Pediatrics 1993;91:1203–1209.
Law WY, Bradley DM, Lazarus JH, John R, Gregory JW: Congenital hypothyroidism in Wales (1982–1993): Demographic features, clinical presentation and effects on early neurodevelopment. Clin Endocrinol 1998;48:201–207.
Hulse JA: Outcome for congenital hypothyroidism. Arch Dis Child 1984;59:23–30.
Grant DB: Growth in early treated congenital hypothyroidism. Arch Dis Child 1994;70:464–468.
Salerno M, Militerni R, Bravaccio B, Micillo M, Capalbo D, di Maio S, Tenore A: Effect of different starting doses of levothyroxine on growth and intellectual outcome at four years of age in congenital hypothyroidism. Thyroid 2002;12:45–52.
Heyerdahl S, Kase BF: Significance of elevated serum thyrotropin during treatment of congenital hypothyroidism. Acta Paediatr 1995;84:634–638.
Touati G, Leger J, Toublane JE, Farriaux JP, Stuckens C, Ponte C, David M, Rocchicoli P, Porquet D, Czernichow P: A thyroxine dosage of 8 mcg/kg/day is appropriate for initial treatment of the majority of infants with congenital hypothyroidism. Eur J Pediatr 1997;156:94–98.
Abusrewil SSA, Tyfield L, Savage DCL: Serum thyroxine and thyroid stimulating hormone concentrations after treatment of congenital hypothyroidism. Arch Dis Child 1988;63:1368–1371.
Grant DB, Fuggle PW, Smith I: Increased plasma thyroid stimulating hormone in treated congenital hypothyroidism: Relation to severity of hypothyroidism, plasma thyroid hormone status and daily dose of thyroxine. Arch Dis Child 1993;69:555–558.
Redmond GP, Soyka LF: Abnormal TSH secretory dynamics in congenital hypothyroidism. J Pediatr 1981;98:83–85.
Brown J, Datta V, Sutton AJ, Swift PGF: Suppression of TSH in congenital hypothyroidism is significantly related to serum levels and dosage of thyroxine. Horm Res 2003;59:85–90.
Grant DB: Monitoring TSH concentrations during treatment for congenital hypothyroidism. Arch Dis Child 1991;66:669–671.
Eldar D, Kaiserman I, Sack J: Early identification of congenital hypothyroid infants with abnormalities in pituitary setpoint for T4-induced TSH release. Horm Res 1993;40:194–200.
Muir A, Daneman D, Daneman A, Ehrlich R: Thyroid scanning, ultrasound and serum thyroglobulin in determining the origin of congenital hypothyroidism. Am J Dis Child 1988;142:214–216.
Sfakianakis GN, Ezuddin SH, Sanchez JE, Eidson M, Cleveland W: Pertechnetate scintigraphy in primary congenital hypothyroidism. J Nucl Med 1999;40:799–804.
Germak JA, Foley TP: Longitudinal assessment of L-thyroxine therapy for congenital hypothyroidism. J Pediatr 1990;2:211–219.
Hanakoglu A, Perlman K, Shamis I, Brnjac L, Rovet J, Daneman D: Relationship of etiology to treatment in congenital hypothyroidism. J Clin Endocrinol Metab 2002;86:186–191.
Ng SM, Wong SC, Didi M: Head circumference and linear growth during the first 3 years in treated congenital hypothyroidism in relation to aetiology and initial biochemical severity. Clin Endocrinol 2003;61:155–159.
Raza J, Hindmarsh PC, Brook CGD: Factors involved in the rate of fall of thyroid-stimulating hormone in treated hypothyroidism. Arch Dis Child 1997;77:526–527.
Hulse JA, Grant DB, Jackson D, Clayton BE: Growth, development and reassessment of hypothyroid infants diagnosed by screening. BMJ 1982;284:1435–1437.
Chiovato L, Giusti L, Tonacchera M: Evaluation of L-thyroxine replacement therapy in children with congenital hypothyroidism. J Endocrinol Invest 1991;14:957–964.
LaFranchi S: Congenital hypothyroidism: Etiologies, diagnosis and management. Thyroid 1999;9:735–740.
Song S, Daneman D, Rovet J: Influence of aetiology and treatment factors on intellectual outcome in congenital hypothyroidism. J Dev Behav Pediatr 2001;22:376–384.
Rovet JF, Ehrlich RM: Long term effects of L-thyroxine therapy for congenital hypothyroidism. J Pediatr 1995;126:380–386.
Selva KA, Mandel SH, Rien L, Sesser D, Miyahira R, Skeels M, Nelson JC, LaFranchi SH: Initial treatment dose of L-thyroxine in congenital hypothyroidism. J Pediatr 2002;141:786–792.
Schultz RM, Glassman MS, Macgillivary MH: Elevated threshold for thyrotropin suppression in congenital hypothyroidism. Am J Dis Child 1980;134:19–20.
Working group on neonatal screening of the European Society of Paediatric Endocrinology: Revised guidelines for neonatal screening programmes for primary congenital hypothyroidism. Horm Res 1999;52:49–52.
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.