Serum somatomedin activity (SSA) in children with operated craniopharyngioma and paradoxical growth

Abstract

SSA was measured by bioassay in 27 sera from 15 children aged 5 to 15 operated for craniopharyngioma (CP). All had complete GH deficiency, none received hGH. Plasma T4 was normalized by administration of thyroid powder. 14 received hydrocortisone (HC) 8-25 mg/m2/day, 13 did not. Growth velocity (GV) ranged 0 to 7.5 cm/year. SSA ranged 0.18 to 1.5 U/ml. No correlation was found between SSA and : daily dose of HC, insulin peak after arginine, delay from surgery, % of weight excess. A positive correlation was found between SSA and GV (r = 0.81, p < 0.001). Moreover, in patients receiving no HC therapy, GV correlated negatively to plasma HC (r = -0.656, p < 0.02). These data demonstrate 1/ that the generation of SSA after removal of CP is independant from GH secretion and is not related to insulin secretion nor to weight excess or to the therapeutic dose of HC ; 2/ that the paradoxical growth in these patients is closely parallel to SSA and negatively correlated to endogenous plasma HC.