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Insulin‐like growth factor‐I and IGF binding protein‐3 remain high after GnRH analogue therapy in girls with central precocious puberty
Author(s) -
Kanety Hannah,
Karasik Avraham,
Pariente Clara,
Kauschansky Arieh
Publication year - 1996
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1996.tb02053.x
Subject(s) - immunoradiometric assay , medicine , endocrinology , insulin like growth factor binding protein , precocious puberty , insulin like growth factor , somatomedin , central precocious puberty , growth factor , radioimmunoassay , receptor , hormone
Summary OBJECTIVE IGF‐I rises in normal adolescence and in central precocious puberty (CPP), secondary to a rise in sex steroids and GH. The aim of this study was to examine changes in serum IGF‐I and its major binding protein IGFBP‐3 after pharmacological arrest of puberty. PATIENTS AND MEASUREMENTS Ten girls diagnosed for CPP were evaluated before and during the first 3 months of GnRH analogue (GnRHa) therapy aimed at Suppression of the gonadal axis. Serum IGF‐I was measured by immunoradiometric assay (IRMA) and IGFBP‐3 by both IRMA and Western ligand blotting (WLB). RESULTS Serum IGF‐I was markedly higher in patients with CPP as compared with age matched controls (48.8 ± 6.5 vs 23.1 ± 4.9 nmol/l, P < 0.01). While GnRHa therapy caused serum oestradiol levels to return to pre‐pubertal levels in all 10 patients, serum IGF‐I levels decreased only minimally after 1, 2 or 3 months of therapy (43.2 ± 5.6, 42.3 ± 6.4 and 44.1 ± 7.2 nmol/l respectively). Serum IGFBP‐3 levels as determined using IRMA were also higher in CPP compared with age matched controls (4.70 ± 0.37 vs 3.71 ± 0.42mg/l, P < 0.01). These differences were also evident when measured by WLB. GnRHa therapy caused a small and insignificant decrease in serum IGFBP‐3 levels after 1, 2 or 3 months of therapy (4.57 ± 0.33, 4.48 ± 0.4 and 4.42 ± 0.3 mg/l respectively). CONCLUSIONS The lack of suppression of both IGF‐I and IGFBP‐3, despite therapy which halts puberty and slows growth velocity, suggests that steroids may be involved In the Induction of changes in the GH/IGF‐I axis but not in their subsequent maintenance.