Pitfalls in the determination of human acylated ghrelin plasma concentrations using a double antibody enzyme immunometric assay.

OBJECTIVES To investigate the effect of hemolysis and protease inhibitors on acylated ghrelin (AG) concentrations measured with a double antibody enzyme immunometric assay that uses an acetylcholinesterase (AChE)-Fab' conjugate. DESIGN AND METHODS Samples were hemolysed or treated with PHMB (p-hydroxymercuribenzoate), PMSF (phenylmethanesulfonylfluoride) or AEBSF (4-(2-Aminoethyl) benzenesulfonyl fluoride) to prevent AG degradation. RESULTS Hemolysis decreased AG concentrations. PHMB or PMSF did not affect the assay. The standard curve was abolished by AEBSF but rescued by addition of a washing step prior to the AChE-Fab' conjugate. CONCLUSIONS Hemolysis and AEBSF may affect AG determination.