The hook effect is not unique to prolactin immunoassays and has been reported with several analytes, particularly tumor markers, where the serum concentrations may become grossly elevated.

Moreover, serial dilution of serum samples should be performed in cases of very large pituitary tumors but only mildly elevated prolactin levels to eliminate the 'hook effect'—an artifact of ...

This high-dose hook effect has been documented with immunoassays for β-hCG, ferritin, prostate-specific antigen, prolactin, thyrotropin, and CA-125. 5 These inaccurate results can be overcome by ...