ESPE Abstracts (2014) 82 P-D-2-1-459

Comparison Between GH assay: serum GH Cut-off Levels by ECLIA Performed in Pharmacological Estimulation Tests in Children With Short Stature

Cecilia Aguirrea, Gabriela Sobreroa, Giselle Schvabb, Liliana Silvanoa, Julia Alvarezb, Mariana Ochettia, Maria Lescurata, Alejandra Paezb, Liliana Muñoza, Silvia Martina & Mirta Mirasa,b

aHospital de Niños Santísima Trinidad, Córdoba, Argentina; bCentro de Endocrinología Pediátrica, Córdoba, Argentina

Background: The diagnosis of GH deficiency in children is based on clinical, auxological, radiographic and biochemical criteria which include response to Pharmacological Estimulation Tests (PhT). It is well known that GH concentrations vary according to the assay method used. Currently in our population, the proposed cut-off value of serum GH PhT is 4.7 ng/ml measured by ICMA using the IRP 98/574.

Objective and hypotheses: The aims of this study were to define GH cut-off level by ECLIA in our population and to compare the concentrations measured by ECLIA and ICMA.

Method: We analyzed 245 PhT performed with arginine n: 175 and clonidine n: 70 (71 F, and 174 M) from 190 children with short stature aged 0.8–16 years. GH concentrations was determined by ICMA (Immulite 2000) and ECLIA (Cobas e 601) using the IRP 98/574.

Results: Linear regression analysis was performed on the 1120 samples measured by ICMA vs ECLIA showing highly significant linearity (y=0.28+0.98 x; R2=0.95). The ECLIA cut-off of 4.65±0.22 ng/ml is the best match with the proposed by ICMA (association coefficient phi=0.88).

Conclusion: Using uniform standardization and the establishment of the cut lines for each methodology and population allows a consistent interpretation of the results.