Background/Aims: Over the years a rise in the incidence of congenital hypothyroidism (CH) has been described worldwide. The aim of our study was to investigate trends in the incidence of CH in Italy over the period 1987-2008, and to investigate which factors may have influenced the CH incidence in our country. Methods: Data were derived from the Italian National Registry of Infants with Congenital Hypothyroidism. Since 1998 the laboratory procedures related to neonatal screening for CH have changed drastically. Accordingly, we estimated the CH incidence during the period 1987-1998 (period 1) and the period 1999-2008 (period 2). Results: The incidence of CH confirmed at birth (including transient hypothyroidism) has increased from 1:3,000 liveborn infants in period 1 to 1:1,940 in period 2 (+54%), whereas the incidence of purely permanent CH increased from 1:3,200 to 1:2,320 (+38%). Lowering of the TSH cutoff was the most important factor contributing to the increase of CH incidence in Italy. Moreover, an increment of 58% of preterm babies with permanent CH was found in period 2 compared with period 1. Conclusion: Our results suggest that more than one cause is responsible for the rise in the increasing CH incidence, with lowering of the screening TSH cutoff and an increased survival rate of a growing number of preterm babies both playing an important role.

Keywords:
Congenital hypothyroidism, Incidence, Prematurity, Cutoff levels, Ethnicity
1.
Fisher DA, Dussault JH, Foley TP Jr, et al: Screening for congenital hypothyroidism: results of screening one million North American infants. J Pediatr 1979;94:700-705.
2.
Mitchell ML, Hsu HW, Sahai I; Massachussetts Pediatric Endocrine Work Group: The increased incidence of congenital hypothyroidism: fact or fancy? Clin Endocrinol (Oxf) 2011;75:806-811.
3.
Mengreli C, Kanaka-Gantenbein C, Girginoudis P, et al: Screening for congenital hypothyroidism: the significance of threshold limit in false-negative results. J Clin Endocrinol Metab 2010;95:4283-4290.
4.
Deladoey J, Ruel J, Giguere Y, Van Vliet G: Is the incidence of congenital hypothyroidism really increasing? A 20-year retrospective population-based study in Quebec. J Clin Endocrinol Metab 2011;96:2422-2429.
5.
Albert BB, Cutfield WS, Webster D, et al: Etiology of increasing incidence of congenital hypothyroidism in New Zealand from 1993-2010. J Clin Endocrinol Metab 2012;97:3155-3160.
6.
Kurinczuk JJ, Bower C, Lewis B, Byrne G: Congenital hypothyroidism in Western Australia 1981-1998. J Paediatr Chlid Health 2002;38:187-191.
7.
Medda E, Olivieri A, Stazi MA, et al: Risk factors for congenital hypothyroidism: results of a population case-control study (1997-2003). Eur J Endocrinol 2005;153:765-773.
8.
Abdelmoktader AM: Risk factors for congenital hypothyroidism in Egypt: results of a population case-control study (2003-2010). Ann Saudi Med 2013;33:273-276.
9.
Rezaeian S, Poorolajal J, Moghimbegi A, Esmailnasab N: Risk factors of congenital hypothyroidism using propensity score: a matched case-control study. J Res Health Sci 2013;13:151-156.
10.
Ford G, LaFranchi S: Screening for congenital hypothyroidism: a worldwide view of strategies. Best Practice Res Clin Endocrinol Metab 2014;28:175-187.
11.
Corbetta C, Weber G, Cortinovis F, et al: A 7-year experience with low blood cutoff levels for neonatal screening reveals an unsuspected frequency of congenital hypothyroidism (CH). Clin Endocrinol (Oxf) 2009;71:739-745.
12.
Parks JS, Lin M, Grosse SD, et al: The impact of transient hypothyroidism on the increasing rate of congenital hypothyroidism in the United States. Pediatrics 2010;125:S54-S63.
13.
Hetzberg V, Mei J, Therrell BL: Effect of laboratory practices on the incidence rate of congenital hypothyroidism. Pediatrics 2010;125:S48-S53.
14.
Hinton CF, Harris KB, Borgfeld L, et al: Trends in incidence rates of congenital hypothyroidism related to select demographic factors: data from the United States, California, Massachusetts, New York and Texas. Pediatrics 2010;125:S37-S47.
15.
Nakamizo M, Toyabe S, Asami T, Akazawa K: Seasonality in the incidence of congenital hypothyroidism in Japan. J Pediatr Child Health 2005;41:390-391.
16.
Gu YH, Kato T, Harada S, Inomata H, Saito T, Aoki K: Seasonality in the incidence of congenital hypothyroidism in Japan: gender-specific patterns and correlation with temperature. Thyroid 2007;17:869-874.
17.
Deladoey J, Belanger N, Van Vliet G: Random variability in congenital hypothyroidism from thyroid dysgenesis over 16 years in Quebec. J Clin Endocrinol Metab 2007;92:3158-3161.
18.
Reijneveld SA, Verkerk PH: No evidence for seasonality of congenital hypothyroidism in the Netherlands. Acta Paediatr 1993;82:212-213.
19.
Olivieri A, The Study Group for Congenital Hypothyroidism: The Italian National Register of infants with congenital hypothyroidism: twenty years of surveillance and study of congenital hypothyroidism. Ital J Pediatr 2009;35:2.
20.
Cassio A, Corbetta C, Antonozzi I, et al: The Italian screening program for primary congenital hypothyroidism: actions to improve screening, diagnosis, follow-up, and surveillance. J Endocrinol Invest 2013;36:195-203.
21.
Bijarnia S, Wilcken B, Wiley VC: Newborn screening for congenital hypothyroidism in very-low-birth-weight babies: the need for a second test. J Inherit Metab Dis 2011;34:827-833.
22.
Clinical and Laboratory Standards Institute (CLSI): Newborn Screening for Preterm, Low Birth Weight, and Sick Newborns; Approved Guideline (No. 24, CLSI Document I/LA31-A). Wayne, CLSI, 2009, vol 29.
23.
Fisher DA: Thyroid system immaturities in very low birth weight premature infants. Semin Perinatol 2008;32:387-397.
24.
Olivieri A, Medda E, De Angelis S, et al: High risk of congenital hypothyroidism in multiple pregnancies. J Clin Endocrinol Metab 2007;92:3141-3147.
25.
Goldsmit GS, Valdes M, Herzovich V, et al: Evaluation and clinical application of changes in thyroid hormone and TSH levels in critically ill full-term newborns. J Perinat Med 2011;39:59-64.
26.
Re RN, Kourides IA, Ridgway EC, Weintraub BD, Maloof F: The effect of glucocorticoid administration on human pituitary secretion of thyrotropin and prolactin. J Clin Endocrinol Metab 1976;43:338-346.
27.
Filippi L, Pezzati M, Poggi C, Rossi S, Cecchi A, Santoro C: Dopamine versus dobutamine in very low birthweight infants: endocrine effects. Arch Dis Child Fetal Neonatal Ed 2007;92:F367-F371.
28.
Williams FL, Ogston SA, van Toor H, Visser TJ, Hume R: Serum thyroid hormones in preterm infants: associations with postnatal illnesses and drug usage. J Clin Endocrinol Metab 2005;90:5954-5963.
29.
Golombek SG: Nonthyroidal illness syndrome and euthyroid sick syndrome in intensive care patients. Semin Perinatol 2008:32:413-418.
30.
Leger J, Olivieri A, Donaldson M, et al: European Society for Paediatric Endocrinology Consensus Guidelines on screening, diagnosis, and management of congenital hypothyroidism. Horm Res Paediatr 2014;81:80-103.
31.
Elminger MW, Kuhnel W, Lambrecht HG: Reference intervals from birth to adulthood for serum thyroxine (T4), triiodothyronine (T3), freeT3, freeT4, thyroxine binding globuline (TBG) and thyrotropin (TSH). Clin Chem Lab Med 2001;39:973-979.
32.
Williams FL, Simpson J, Delahunty C, et al: Developmental trends in cord and postpartum serum thyroid hormones in preterm infants. J Clin Endocrinol Metab 2004;89:5314-5320.
33.
Olivieri A, Corbetta C, Weber G, et al: Congenital hypothyroidism due to defects of thyroid development and mild increase of TSH at screening: data from the Italian National Registry of Infants with Congenital Hypothyroidism. J Clin Endocrinol Metab 2013;98:1403-1408.
34.
Beck S, Wojdyla D, Say L, et al: The worldwide incidence of preterm birth: a systematic review of maternal mortality and morbidity. Bull World Health Organ 2010;88:31-38.
35.
Wassner AJ, Brown RS: Hypothyroidism in the newborn period. Curr Opin Endocrinol Diabetes Obes 2013;20:449-454.
36.
International Council for Control of Iodine Deficiency Disorders: Global Iodine Nutrition Scorecard. http://www.iccidd.org/cm_data/Scorecard_ICCIDD_website_18_12_2012_updated_MCD.pdf.
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2015
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