Do you pursue further workup for a coexisting cause of true hyperprolactinemia, or attribute the elevation to macroprolactin and observe, when PEG precipitation confirms macroprolactinemia but the post-PEG monomeric prolactin remains above the normal range?

Macroprolactinemia can coexist with real hyperprolactinemia. The post-PEG precipitation monomeric prolactin value, rather than percent recovery alone, is the most informative parameter for distinguishing isolated macroprolactinemia from coexisting true hyperprolactinemia. If monomeric prolactin is e...