Growth hormone binding proteins and various forms of growth hormone: implications for measurements.

GH measurements are complicated by numerous physiologically occurring GH forms, by the lack of availability of completely specific reagents for the various GH isoforms, and by interference of the circulating BP in some assays. The discrepancies between assay results are partly due to these factors, with monoclonal immunoassays or RRAs being more affected than polyclonal immunoassays.