Macroprolactin and macroprolactinaemia: A narrative review

Abstract

Background: Macroprolactin is a heteropolymeric complex of monomeric prolactin and immunoglobulin G (IgG) with little or no biological activity in vivo. Macroprolactinaemia is a notable cause of misdiagnosis and unnecessary treatment of patients with biochemical hyperprolactinaemia. Hence, it needs to be excluded in all patients with laboratory-established increase in serum prolactin levels. The polyethylene-glycol (PEG) precipitation method is commonly used for the routine laboratory screening for macroprolactinaemia. Objective: To review the concept of macroprolactinaemia and its impact on the clinical manifestations, biochemical features, laboratory and radiological evaluations, and management of patients with hyperprolactinaemia. Method: Review of available literature and selected references on macroprolactinaemia and its contribution to the aetiology of biochemical hyperprolactinaemia. Conclusion: Macroprolactinaemia is diagnostically and clinically important in reproductive endocrinology practice. Routine laboratory screening of macroprolactinaemia using the PEG-precipitation method is highly recommended for all cases of hyperprolactinaemia.