Comparison of six radioimmunoassay kits for human follitropin in serum.

Six commercially available radioimmunoassay (RIA) kits for human follitropin (follicle-stimulating hormone; hFSH) were compared with respect to precision, "accuracy", specificity and performance. The intra- and interassay coefficients of variation ranged from 4.7 to 8.3% and from 6.5 to 13.3%, respectively. The recovery of added follitropin ranged from 88 to 176%. The most important conclusion of this study is that an accurate calibration of the kit standard by the manufacturer is essential for minimizing the variation between kits.