As autoimmunity has been related to the prevalence and pathogenesis of hyperprolactinemia,32 the following autoantibodies including ANA, aTPO, and aTG were tested for all the Group 1 and Group 2 patients that were suspected for macroprolactinemia with low PEG recovery rates (<60%) (Figure 1). Here, BTG3 is linked to hyperprolactinemia.