We are attempting to measure isomers of growth hormone other than the standard 22 kDa variant. It would appear that the antibodies used in standard ELISAs are not appropriate for this. Kraemer et al. have used the Nichol's IRMA, but the Nichols Institute appears to have been bought out by Quest, and we have not been able to make contact with the appropriate people. We are curious as whether others have successfully secured antibodies which might be appropriate to detect higher MW variants of growth hormone.