Comparison of two immunoassays in the determination of IGF-I levels and its correlation with oral glucose tolerance test (OGTT) and with clinical symptoms in acromegalic patients |
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Authors: | Laura Boero Marcos Manavela Karina Danilowicz Analia Alfieri Maria Carolina Ballarino Alberto Chervin Natalia García-Basavilbaso Mariela Glerean Mirtha Guitelman Monica Graciela Loto Jose Alberto Nahmías Amelia Susana Rogozinski Marisa Servidio Nicolas Marcelo Vitale Débora Katz Patricia Fainstein Day Graciela Stalldecker Maria Susana Mallea-Gil |
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Affiliation: | Departamento de Neuroendocrinología (Neuroendocrinology Department), Sociedad Argentina de Endocrinología y Metabolismo, Diaz Velez 3889, (1200), Buenos Aires, Argentina, lauraboero@fibertel.com.ar. |
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Abstract: | The aim of our study was to evaluate two different methodologies in IGF-I levels determination, its correlation with GH nadir in OGTT <1 and <0.4?ng/ml and with clinical symptoms in acromegalic patients. We analyzed 37 patients. Sixteen patients had not undergone any kind of treatment (Group 1). Twenty-one patients underwent surgery as primary treatment, and after that, some of them another kind of treatment (except pegvisomant) (Group 2). Serum IGF-I levels were measured by Immulite-1000 (IMM) and by an immunoradiometric assay (DSL) and, GH by immunochemiluminometric assay. IGF-I levels by IMM and by DSL showed a significant difference. When we analyzed in both groups the concordance by crosstabs-Kappa coefficients, between different parameters, GH nadir <1 and <0.4?ng/ml with IGF-I by DSL and IMM showed concordance in group 1, but in group 2 only GH nadir <1 and <0.4?ng/ml had a weak concordance with IGF-I by IMM. When we analyzed clinical symptoms in the patients and, GH nadir <1 and <0.4?ng/ml and IGF-I levels by both methodologies, more than 90% of clinically active patients had abnormal GH response or/and elevated IGF-I levels in group 1, but less than 70% in group 2. In the 8 patients under medical treatment, GH nadir was higher than 0.4?ng/ml in all patients, and IGF-I levels were elevated in 8/8 by DSL and in 6/8 by IMM. In conclusion, discrepant GH and IGF-I levels in the diagnosis and follow-up of patients with acromegaly requires consideration of many factors that influence these parameters. |
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