B S Schütt1, K Weber, M W Elmlinger, M B Ranke. 1. Paediatric Endocrinology Section, University Children's Hospital, Hoppe-Seyler Strasse 1, D-72076 Tübingen, Germany.
Abstract
OBJECTIVE: The aim of this study is to adapt measurements of IGF-I, IGFBP-2 and IGFBP-3 to dried blood filter disk assays. METHODS: Measurements of the three analytes in serum samples and in the corresponding blood spotted onto filter paper were compared by applying standard radioimmunoassays. RESULTS: In paired experiments, the quantity of all antigens measured on dried filter spots showed an excellent correlation to that in serum (R>0.88) and in addition this correlation was independent of the whole blood hematocrit value. Recovery of IGF-I, IGFBP-2 and IGFBP-3 in experiments using recombinant standards mixed with whole blood was well correlated with the recovery of the plasma fraction on the filter paper. All of the blood spot assays showed a inter- and intra-assay variation of less than 10% and the blood spots were stable over a period of more than 5 months stored at -20 degrees C. CONCLUSIONS: Taken together, these data clearly demonstrate that such a filter paper assay is a reliable procedure to monitor changes of IGF-I, IGFBP-2 and IGFBP-3 content in blood. The obvious advantages of this methods concerning storage, handling and shipping of blood probes helps to solve the logistics of centralised measurements of these three analytes.
OBJECTIVE: The aim of this study is to adapt measurements of IGF-I, IGFBP-2 and IGFBP-3 to dried blood filter disk assays. METHODS: Measurements of the three analytes in serum samples and in the corresponding blood spotted onto filter paper were compared by applying standard radioimmunoassays. RESULTS: In paired experiments, the quantity of all antigens measured on dried filter spots showed an excellent correlation to that in serum (R>0.88) and in addition this correlation was independent of the whole blood hematocrit value. Recovery of IGF-I, IGFBP-2 and IGFBP-3 in experiments using recombinant standards mixed with whole blood was well correlated with the recovery of the plasma fraction on the filter paper. All of the blood spot assays showed a inter- and intra-assay variation of less than 10% and the blood spots were stable over a period of more than 5 months stored at -20 degrees C. CONCLUSIONS: Taken together, these data clearly demonstrate that such a filter paper assay is a reliable procedure to monitor changes of IGF-I, IGFBP-2 and IGFBP-3 content in blood. The obvious advantages of this methods concerning storage, handling and shipping of blood probes helps to solve the logistics of centralised measurements of these three analytes.
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