Abstract 5

Aiming to evaluated the role of thyroid hormones in the regulation of IGFBPs serum levels we studied 35 hypothyroid children prior to and during Levothyroxine (LT) treatment (time interval between samples: 1-16 months) TSH, T4, IGF-1 were measured by RIAS (IGF-1 after acid-ethanol extraction). Serum total IGF-II binding capacity (TBC) was measured according to Cailleau et al (Mol. Cell. Endocrinol. 69:79, 1990). IGFBP3 was measured by IRMA (DSL). IGFBP2 was measured by immunoblot after SDS-PAGE and transfer to a nitrocellulose membrane. Before treatment all patients had TSH > 35 µg/ml. During treatment all patients showed normal T4 and 31/35 normal TSH. RESULTS (mean ± SEM, Wilcoxon test). Table CONCLUSIONS: we found age-related differences in the TBC & IGFBP2 responses to LT. Under LT treatment IGF-1 & IGFBP3 increased independently of age, but TBC & IGFBP2 decreased significantly only in patients with CA < 5 yr. In this age group all the changes found are compatible with an increase in GH secretion under LT treatment. The increase in IGF-I and IGFBP3 in patients with CA > 5yr supports the same GH changes in this age group, but accompanied by a different behaviour of the low molecular weight IGFBPs. The lack of modifications in TBC & IGFBP2 suggests possible compensatory variations of other/s IGFBP/s.

Table 1 No caption available.
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