Low Growth Hormone-Binding Protein in Infants with Congenital Hypothyroidism

• Published in: The journal of clinical endocrinology and metabolism 1998-10, Vol.83 (10), p.3643-3646
• Main Authors: Cassio, Alessandra, Cacciari, Emanuele, Balsamo, Antonio, Colli, Cristina, Pasini, Andrea, Salvioli, Gian Paolo, Lanari, Marcello, de Iasio, Rosaria, Boschi, Stefano, Pirazzoli, Piero
• Format: Article
• Language: English
• Subjects: Congenital diseases; Fetuses; Growth hormones; High-performance liquid chromatography; Hypothyroidism; Infants; Insulin-like growth factor I; Insulin-like growth factor-binding protein 3; Insulin-like growth factors; Neonates; Proteins; Thyroxine
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jcem.83.10.5173

We evaluated the circulating levels of GH, insulin-like growth factor I (IGF-I), GH-binding protein (GHBP), and IGF-binding protein-3 (IGFBP-3) before l-T4 therapy in 19 infants with congenital hypothyroidism (CH), aged 12–29 days, diagnosed by neonatal screening and in a group of age- and sex-matched control infants. The same parameters were reevaluated after several months of treatment. Serum GHBP was measured by the high performance liquid chromatography-gel filtration method; serum GH, IGF-I, and IGFBP-3 levels were determined by commercial kits. The hypothyroid patients, before beginning therapy, presented significantly lower GHBP values than controls (P < 0.0001); during treatment, these values increased significantly; however, after 6 months they were still significantly lower than control values (P < 0.01). The pretreatment levels of GH were not significantly different from control values; after 1 month of treatment, GH did not show the decrease observed in controls and, therefore, was significantly higher (P < 0.01). The pretreatment levels of IGF-I were not significantly different from control values, but were lower in patients with severe than in those with mild hypothyroidism. They decreased at about 4 months of life and became significantly lower than control values at about 7 months of age (P < 0.05). In conclusion, it may be hypothesized that the condition of CH induces a change in GHBP expression, perhaps beginning in fetal life. The intrauterine production of IGF-I seems to be independent of the levels of GHBP and partially affected by fetal thyroid function.