Hormona de crecimiento en sangre de papel filtro para el diagnóstico de deficiencia de hormona de crecimiento / Growth hormone of dried blood spot for the diagnosis of growth hormone deficiency

INTRODUCCIÓN: El diagnóstico de deficiencia de hormona de crecimiento (DHC) es difícil de establecer, y se puede asociar a serias complicaciones, especialmente en el período neonatal. La prueba de estímulo de secreción de hormona de crecimiento (HC) se considera de elección para el diagnóstico, pero presenta complicaciones metodológicas y se asocia a efectos adversos. Los neonatos presentan aumento de la secreción de HC de forma fisiológica, siendo una ventana diagnóstica. OBJETIVO: Evaluar si la muestra de sangre en papel filtro tomada en el período neonatal, en contexto del tamizaje neonatal de hipotiroidismo congénito y fenilcetonuria, permite diferenciar pacientes con DHC, de los que no la presentan. PACIENTES Y MÉTODO: Estudio de casos y controles mediante determinación de concentración de HC en sangre de papel filtro extraída en período neonatal, comparando controles con DHC con casos con deficiencia descartada. Se realizó extracción de la muestra del papel filtro, obteniendo dos discos de 0,125 pulgada por cada uno de los pacientes desde el centro de la mancha de sangre del papel, para un ELISA de HC humana altamente sensible basado en el uso de anticuerpos policlonales dirigidos contra la HC humana recombinante de 22kDa de peso molecular. RESULTADOS: Se obtuvo un total de 7 casos de DHC y 10 controles. La mediana de concentración de HC de papel filtro en los casos es 2,0 ng/ml (Rango intercuartil 3,6 ng/ml) y controles 2,05 ng/mL (RIC 2,0 ng/ml), U de Mann-Withney 30,5 (p = 0,68). Los dos casos con deficiencia de hormonas hipofisarias múltiples (DHHM) presentan concentraciones menores a 1 ng/ml. CONCLUSIÓN: La muestra de papel filtro no permitió diferenciar a los pacientes con DHC de los casos controles, aunque los casos con DHHM presentaron concentraciones mucho menores, en comparación a la deficiencia de hormona de crecimiento aislada (DHCA).

INTRODUCTION: The diagnosis of growth hormone deficiency (GHD) is difficult to determine, and could be associated with severe complications, especially in the neonatal period. The stimulation test of growth hormone (GH) secretion is considered the gold standard for diagnosis, but it has methodological complications and is associated with adverse effects. Neonates present physiological increased secretion of GH, representing a diagnostic window. OBJECTIVE: To evaluate if the dried blood spot on filter paper obtained in the neonatal period, as part of a neonatal screening for con genital hypothyroidism and phenylketonuria, allows differentiating patients with GHD from those who do not have it. PATIENTS AND METHOD: Study of cases and controls by measuring the GH concen tration in dried blood spot on filter paper obtained in the neonatal period, comparing controls with GHD with cases with discarded deficiency. The sample was extracted from the filter paper, obtaining two 0.125 inch discs per each patient from the center of the blood spot on the paper, for a highly sen sitive ELISA assay for human GH based on the use of polyclonal antibodies against 22 kDa recom binant human GH. RESULTS: Seven cases of GHD and ten controls were obtained. The median GH concentration of the dried blood spot in the cases is 2.0 ng/ml (Interquartile range 3.6 ng/ml) and 2.05 ng/ml (Interquartile range 2.0 ng/ml) in the controls, Mann-Whitney U test 30.5 (p = 0.68). The two cases with multiple pituitary-hormone deficiency (MPHD) present concentrations lower than 1 ng/ml. CONCLUSION: The dried blood spot sample did not differentiate GHD patients from control cases, although MPHD cases present much lower concentrations compared to isolated growth hor mone deficiency (IGHD).

Measurement of IGF-1, IGFBP-3 and free IGF-1 levels by ELISA in growth hormone (GH) deficient children before and after GH replacement.

Serum insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) levels reflect the growth hormone (GH) status. A few percent of IGF-1 circulate in a free form which is believed to represent the IGF biological activity. We retrospectively studied the changes of serum IGF-1, serum IGFBP-3, and plasma free IGF-1 levels in growth hormone deficient (GHD) children before and after treatment with recombinant human growth hormone (rhGH) for a period of 6 months and 1 year. Twenty-one GHD children (16 boys and 5 girls) who had the mean chronological and bone ages of 7.7 +/- 0.7 and 4.8 +/- 0.6 years, respectively, were treated with a mean rhGH dose of 11.66 +/- 0.42 U/m2 body surface area/week. Serum IGF-1 level increased from 162.5 +/- 42.9 ng/ml before treatment to 252.8 +/- 49.5 ng/ml (p = 0.007) and 282.7 +/- 86.9 ng/ml after treatment for 6 months and 1 year, respectively. Plasma free IGF-1 also increased from 0.38 +/- 0.30 ng/ml before treatment to 1.21 +/- 0.30 (p = 0.001) and 1.17 +/- 0.42 ng/ml after 6 months and 1 year of treatment. However, serum IGFBP-3 did not significantly increase after treatment. In addition, the free/total IGF-1 ratio decreased after treatment with rhGH. The height velocities at 6 months and 1 year after treatment were negatively correlated with plasma free IGF-1 before treatment. In conclusion, therefore, plasma free IGF-1 levels could serve as a good predictor of growth hormone responses. Furthermore, their circulating levels would be modified by serum IGF-1 status, and possibly, IGFBP-3 protease activity.

Defective growth hormone (GH) secretion and short-term treatment in Noonan syndrome.

Auxological and endocrine data from 12 prepubertal children (3 males, 9 females) with Noonan syndrome (NS) were compared with those of 15 children with constitutional short stature (CSS), 20 children with partial GH deficiency (GHD), and 6 children with Turner syndrome (TS). Four children with NS were treated with human growth hormone (hGH) (n = 4) (25 units/m2 week, divided on daily s.c. doses). In children with NS, the peak serum GH response to clonidine (5.4 +/- 2.7 ug/L) and glucagon (7.4 +/- 3.4 ug/L) were significantly lower than those for children with CSS (14.8 +/- 3.4 and 12.8 +/- 2.8 ug/L respectively). Nine out of the 12 (75%) children with NS did not mount normal GH peak (10 ug/L or more) after provocation. The 12-h integrated GH secretion in the 3 children with NS who had normal GH response to provocation (2.7 +/- 0.7 ug/L) was markedly lower compared to that for children with CSS (6.7 +/- 1.2 ug/L). The serum insulin-like growth factor-1 (IGF-I) concentrations were lower in children with NS (67 +/- 32 ng/ml) vs CSS (165 +/- 35 ng/ml), but not different from those for GHD children (59 +/- 33 ng/ml). In 4 children with NS, hGH therapy for a year increased height growth velocity from 4.1 +/- 0.3 cm/yr to 7.4 +/- 0.6 cm/yr and height standard deviation score (Ht SDS) from -2.2 +/- 0.6 to -1.45 +/- 0.3. This growth acceleration was accompanied by an increase in IGF-I concentration (from 52 +/- 21 ng/ml to 89 +/- 25 ng/ml). In summary, these results prove a defect of the GH secretion in children with NS and suggest that GH therapy has an important role in the management of their short stature.