Valores de referencia para proteína transportadora de hormona de crecimiento en una población pediátrica normal / Normative values of growth hormone binding protein, GHBP, for a chilean pediatric population

Circulating concentrations of the high affinity growth hormone binding protein (GHBP) may be a marker of GH receptor density as well as GH sensiffvity. Goal: To determine values of GHBP for a normal Chilean pediatric population. Methods : We determined GHBP levels in 73 males and 73 females between 4 to 15.5 years and 4 to 16.8 years respectively, divided in 7 groups according to age and puberal status. Results: The population was normally distributed in weight, height and body mass index (BMI). GHBP activity increased up to Tanner IV in males and Tanner III in females, and decreased slightly thereafter in Tanner V and IV respectively. There was a significant difference between GHBP levels of preschool children and those found in Tanner II to V in both sexes (p<0.05). In adition, we found a positive correlation between GHBP vs weight, height and BMI (p<0.001) in males and females. Conclusion : The availability of this methodology allows us to establish the normative value of GHBP in our population and provides useful information to interpret GH circulating levels in children with growth disorders

Utilidad de la determinación del factor de crecimiento insulino-simil tipo I (IGF-I) y de su proteína ligante tipo 3 (IGFBP-3) en el diagnóstico de la deficiencia de hormona de crecimiento en niños / Usefulness of the measurement of insulin-like growth factor 1 (IGF-I) and IGF-1 binding protein-3 (IGFBP-3) for the diagnosis of growth hormone (GH) deficiency in children

Background: The diagnosis of GH deficiency (GHD) is based upon the results of GH stimulation tests, which have several drawbacks. Aim: To evaluate the usefulness of IGF-1 and IGFBP-3 for the diagnosis of GHD in prepuberal children. Material and methods: We measured IGF-I and IGFBP-3 in three group of subjects: I. GHD (n:24), height <-2SD for age (Z score, average ñ SD: -4.2 ñ 1.2), growth velocity 7 ng/ml (15.3 ñ 6.9 ng/ml), y III. Normal school children (n:35) with normal heights (-0.17 ñ 0.12 SD) were studied as controls. Results: IGF-1 and IGFBP-3 were significantly lower in GHD than in NGHD and controls (p <0.001), and in NGHD than in C (p <0.001). We defined the normal range of both proteins as ñ 2 SD of the mean of the control group. Using this criteria, IGF-I was low in 21/24 GHD, and in 12/32 NGHD. IGFBP-3 was low in 22/24 GHD, and in 6/32 NGHD. Only 1 GHD patient had both exams in the normal range, suggesting that he is probably NGHD. 4/32 of the NGHD had both exams below normal range, suggesting that they are probably GHD. Conclusions: IGF-1 and IGFBP-3 are important tools for the diagnosis of GHD