[IGF-I sensitivity in small for gestational age children]. / Sensibilidad a IGF-I en niños pequeños para la edad gestacional.

BACKGROUND: The lack of catch up growth (CUG) in small for gestational age (SGA) children may be related to a reduced sensitivity to insulin growth factor 1 (IGF-I). AIM: To assess the sensitivity to IGF-I in small for gestational age children, measuring basal and post IGF-I nocturnal profile of growth hormone (GH). PATIENTS AND METHODS: We studied 34 prepubertal SGA children aged 4 to 11 years. Twenty three had CUG and 11 did not have CUG. As an IGF-I sensitivity test, nocturnal GH levels were measured every 20 minutes from 23:00 h to 07:00 h, both under baseline conditions and after the administration of a subcutaneous bolus of 1 mg/kg/body weight of the IGF-I + IGFBP-3 complex (Somatokine). RESULTS: At the time of the study, the Z scores for height among children with and without CUG were -1.55 +/- 0.22 and -3.24 +/- 0.28, respectively (p <0.0001). There were no statistical differences between CUG + vs CUG- patients in mean basal GH (6.6 +/- 0.5 and 5.6 +/- 0.6 ng/ml, respectively). After Somatokine administration, mean GH, and the mean GH area under the curve (AUC) decreased significantly in both groups. However, mean overnight GH AUC decreased in all SGA children with CUG, after Somatokine administration, whereas 3 out of 11 SGA children without CUG had an increase in their mean GH AUC in response to Somatokine. CONCLUSIONS: These findings suggest that pituitary sensitivity to IGF-I may be decreased in some SGA children without CUG.

Sensibilidad a IGF-I en niños pequeños para la edad gestacional / IGF-I sensitivity in small for gestational age children

Background: The lack of catch up growth (CUG) in small for gestational age (SGA) children may be related to a reduced sensitivity to insulin growth factor 1 (IGF-I). Aim: To assess the sensitivity to IGF-I in small for gestational age children, measuring basal and post IGF-I nocturnal profile of growth hormone (GH). Patients and methods: We studied 34 prepubertal SGA children aged 4 to 11 years. Twenty three had CUG and 11 did not have CUG. As an IGF-I sensitivity test, nocturnal GH levels were measured every 20 minutes from 23:00 h to 07:00 h, both under baseline conditions and after the administration of a subcutaneous bolus of 1 mg/kg/body weight of the IGF-I + IGFBP-3 complex (Somatokine®). Results: At the time of the study, the Z scores for height among children with and without CUG were -1.55 ± 0.22 and -3.24 ± 0.28, respectively (p <0.0001). There were no statistical differences between CUG + vs CUG- patients in mean basal GH (6.6 ± 0.5 and 5.6 ± 0.6 ng/ml, respectively). After Somatokine® administration, mean GH, and the mean GH area under the curve (AUC) decreased significantly in both groups. However, mean overnight GH AUC decreased in all SGA children with CUG, after Somatokine® administration, whereas 3 out of 11 SGA children without CUG had an increase in their mean GH AUC in response to Somatokine®. Conclusions: These findings suggest that pituitary sensitivity to IGF-I may be decreased in some SGA children without CUG.

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

Efectos de la terapia con fenobarbital en pacientes pediátricos con diferente estado nutricional / Phenobarbital therapy effects on pediatric patients with different nutritional status

El objetivo del presente trabajo fue estudiar si los efectos adversos del fenobarbital en relación a metabolismo fosfocálcico y hepatotoxicidad se acentúan cuando se agrega al cuadro clínico un déficit nutricional. También se determinó la fracción de droga libre del fármaco y su relación con los niveles de albúmina sérica. Se encontró un número importante de niños con estado nutricional normal que presentaba hipoalbuminemia (24,1%), hipofosfatemia (20,7%) y actividad aumentada de las fosfatasas alcalinas (44,8%) y de la transaminasa glutámico oxaloacética (32,1%). Al comparar este grupo con el de los pacientes con déficit nutricional avanzado, se encontró diferencia significativa sólo en relación a fósforo (p<0,025), encontrando un 46,2% con hipofosfatemia y un 42,8% con hipoalbuminemia. Ambos estados nutricionales no mostraron cambios significativos en la fracción de droga libre, no constituyéndose así en otro factor de riesgo