Discrepancies In Gh Deficiency Diagnosis Using Different Commercial Kits

GH levels obtained with three different assay systems [immunoradiometric assay-IRMA (A), radioimmunoassay-RIA (B) and immunofluorometric assay-IFMA (C)] were compared. The results from assays A, B and C were highly correlated. However the relationships between the values obtained with A or C varied considerably from those obtained with B. Our data suggest the following: 1) the differences between IRMA and IFMA methods on one hand and RIA method on the other are more evident evaluating spontaneous GH secretion rather than stimulated GH peaks, 2) the different results obtained may be consistent with either a different variability of the three methods in measuring high GH (stimulation tests) or low GH levels (spontaneous secretion), or with the existence of various circulation forms of GH.