title: Levothyroxine requirement in congenital hypothyroidism: a 12-year longitudinal study.
abstract: The aim of the replacement therapy with levothyroxine in congenital hypothyroidism (CH) is to correct hypothyroidism and ensure normal growth and neuropsychological development. Few data are available about the appropriate dose during childhood and early adolescence; therefore, we performed a multicenter observational study in a large population of patients with CH to assess the required levothyroxine dose to obtain euthyroidism. We recruited 216 patients with permanent CH classified into three groups (agenesia, ectopia, and in situ gland) on the basis of the thyroid imaging. The levothyroxine dose was recorded at 6 and 12 months and then yearly until 12 years of age. The daily levothyroxine requirement progressively decreased during the follow-up, irrespective of etiology. It was significantly lower in patients with in situ gland than in patients with athyreosis during the entire study period and with ectopic gland from the age of 1 year. The levothyroxine requirement at 6 months of age was correlated with the requirement at each later time-point. The daily dose was modified less frequently in patients with in situ thyroid (36 %) than in patients with ectopic gland (41.4 %) or with athyreosis (43.6 %). Patients with in situ gland required a lower dose than the other two subgroups. The dose at 6 months seems predictive of the requirement until 12 years of age. Euthyroidism may be achieved in pre-school and in-school patients by 3-4 and 2-3 µg/kg/day (70-90 and 60-80 µg/m(2)/day) of levothyroxine, respectively.
authors.affiliation: Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro, Bari, Italy. mdelvecchio75@gmail.com.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Delvecchio
authors.affiliation: Pediatric Section-Department of Translational Medical Sciences, University of Naples Federico II, Naples, Italy.
authors.forename: Mariacarolina
authors.initials: M
authors.lastname: Salerno
authors.affiliation: Department of Pediatrics Endocrinology, IRCCS Vita-Salute San Raffaele University, Milan, Italy.
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Vigone
authors.affiliation: Department of Pediatrics, University of Messina, Messina, Italy.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Wasniewska
authors.affiliation: Department of Pediatrics, University of Foggia, Foggia, Italy.
authors.forename: Pietro Pio
authors.initials: PP
authors.lastname: Popolo
authors.affiliation: Department of Pediatrics, University of Foggia, Foggia, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Lapolla
authors.affiliation: Division of Pediatric Endocrinology, Department of Pediatrics, University of Turin, Turin, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Mussa
authors.affiliation: Department of Pediatrics Endocrinology, IRCCS Vita-Salute San Raffaele University, Milan, Italy.
authors.forename: Giulia Maria
authors.initials: GM
authors.lastname: Tronconi
authors.affiliation: Pediatric Section-Department of Translational Medical Sciences, University of Naples Federico II, Naples, Italy.
authors.forename: Ida
authors.initials: I
authors.lastname: D'Acunzo
authors.affiliation: Pediatric Section-Department of Translational Medical Sciences, University of Naples Federico II, Naples, Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Di Mase
authors.affiliation: Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro, Bari, Italy.
authors.forename: Rosa Maria
authors.initials: RM
authors.lastname: Falcone
authors.affiliation: Division of Pediatric Endocrinology, Department of Pediatrics, University of Turin, Turin, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Corrias
authors.affiliation: Department of Pediatrics, University of Messina, Messina, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: De Luca
authors.affiliation: Department of Pediatrics Endocrinology, IRCCS Vita-Salute San Raffaele University, Milan, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Weber
authors.affiliation: Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro, Bari, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Cavallo
authors.affiliation: Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro, Bari, Italy.
authors.forename: Maria Felicia
authors.initials: MF
authors.lastname: Faienza
mesh_terms: D003409:Congenital Hypothyroidism / Q000188:drug therapy* / Q000209:etiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D050033:Thyroid Dysgenesis / Q000150:complications; D013974:Thyroxine / Q000008:administration & dosage*
chemical_list: D013974:Thyroxine
keywords: Congenital hypothyroidism; Congenital hypothyroidism etiology; Congenital hypothyroidism severity; Replacement therapy; Thyroxine requirement