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...

Macroprolactin is usually biologically in active so if the patient has symptoms of hyperprolactinemia, further work up may be needed.