This kit uses enzyme-linked immune sorbent assay (ELISA) based on the Biotin double antibody sandwich technology to assay the Human Ghrelin (GHRL). Add Ghrelin(GHRL)to the wells, which are pre-coated with Ghrelin(GHRL)monoclonal antibody and then incubate. After that, add anti GHRL antibodies labeled with biotin to unite with streptavidin-HRP, which forms immune complex. Remove unbound enzymes after incubation and washing. Add substrate A and B. Then the solution will turn blue and change into yellow with the effect of acid. The shades of solution and the concentration of Human Ghrelin (GHRL) are positively correlated.