Measuring IGF-I, IGFBP-2 and IGFBP-3 from dried blood spots on filter paper is not only practical but also reliable.
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.
Paediatric Endocrinology Section, University Children's Hospital, Hoppe-Seyler Strasse 1, D-72076 Tübingen, Germany.
B S
BS
Schütt
K
K
Weber
M W
MW
Elmlinger
M B
MB
Ranke
D000328:Adult; D001800:Blood Specimen Collection / Q000379:methods*; D002648:Child; D006403:Hematologic Tests / Q000379:methods*; D006801:Humans; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000097:blood*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D011863:Radioimmunoassay; D015203:Reproducibility of Results
D018971:Insulin-Like Growth Factor Binding Protein 2; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I