Serum prolactin measurement is a routine test in several conditions in every day clinical practice, and the finding of hyperprolactinemia can induce complex and expensive imaging studies. Circulating prolactin is a heterogeneous hormone and, from a molecular weight point of view, there are three main forms: the 23kDa monomer, the 45kDa dimer (big prolactin) and the higher than 150kDa macroprolactin, or big-big prolactin. In normal conditions, or in patients with symptomatic hyperprolactinemia, the monomeric form is the predominant. Macroprolactin is […]