Commercial immunoassays for human relaxin-2

Several different immunoassays have been used in the commercial pharmaceutical development of serelaxin. These assays have been well validated for submission of GLP preclinical and clinical studies to the FDA and EU regulatory bodies. The requirements for these assays exceed that of most research assays commonly developed in academic research but have been and are currently available to academic researchers. Additionally, many human relaxin immunoassays are commercially available from a variety of vendors. Validation procedures for immunoassays are well understood and documented, however validation of these assays is often lacking or completely absent. The data derived from these assays must be questioned if the investigator does not supply information on the validation of the assay used, either from the supplier or through their own efforts. Many recent papers on determination of serum relaxin in clinical settings have recently been published. The assay used for this determination varies but generally is one of two commercially available. These manuscripts and the assay used is discussed. Direct comparisons of assays are lacking but some general conclusions can be drawn by comparing results from similar studies using different assays. There is disagreement among the results of the concentrations of serum relaxin from the use of different assays that raise questions on assay reliability. The differences in the quality of immunoassays used for detection of serum relaxin should be part of the decisions making process in choosing an assay. While the end user bears the ultimate responsibility to demonstrate the assay is valid for the stated claims, reviewers and editors also share responsibility for quality of published results. •Many commercial immunoassays for relaxin-2 are available but only two are widely used for clinically relevant publications.•Assay validation varies widely from well characterized to none and authors do not further characterize their assay.•Direct comparisons of assays is lacking but similar studies using different assays have produced very different results.•Using unvalidated relaxin assays leads to unfounded conclusions regarding the role of relaxin in important clinical conditions.