title: 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.
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.
authors.affiliation: Departamento de Neuroendocrinología, Sociedad Argentina de Endocrinología y Metabolismo, Diaz Velez 3889, 1200 Buenos Aires, Argentina. lauraboero@fibertel.com.ar
authors.forename: Laura
authors.initials: L
authors.lastname: Boero
authors.forename: Marcos
authors.initials: M
authors.lastname: Manavela
authors.forename: Karina
authors.initials: K
authors.lastname: Danilowicz
authors.forename: Analia
authors.initials: A
authors.lastname: Alfieri
authors.forename: Maria Carolina
authors.initials: MC
authors.lastname: Ballarino
authors.forename: Alberto
authors.initials: A
authors.lastname: Chervin
authors.forename: Natalia
authors.initials: N
authors.lastname: García-Basavilbaso
authors.forename: Mariela
authors.initials: M
authors.lastname: Glerean
authors.forename: Mirtha
authors.initials: M
authors.lastname: Guitelman
authors.forename: Monica Graciela
authors.initials: MG
authors.lastname: Loto
authors.forename: Jose Alberto
authors.initials: JA
authors.lastname: Nahmías
authors.forename: Amelia Susana
authors.initials: AS
authors.lastname: Rogozinski
authors.forename: Marisa
authors.initials: M
authors.lastname: Servidio
authors.forename: Nicolas Marcelo
authors.initials: NM
authors.lastname: Vitale
authors.forename: Débora
authors.initials: D
authors.lastname: Katz
authors.forename: Patricia
authors.initials: P
authors.lastname: Fainstein Day
authors.forename: Graciela
authors.initials: G
authors.lastname: Stalldecker
authors.forename: Maria Susana
authors.initials: MS
authors.lastname: Mallea-Gil
mesh_terms: D000172:Acromegaly / Q000378:metabolism*; D000328:Adult; D005260:Female; D005951:Glucose Tolerance Test; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged
chemical_list: D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone