Comparison of PEG precipitation and ultrafiltration treatment for serum macroprolactin in Chinese patients with hyperprolactinemia

Macroprolactinemia is a common cause of hyperprolactinemia (HPRL), with an average worldwide incidence of 18.9 %. This study aimed to explore the feasibility of ultrafiltration (UF) and polyethylene glycol (PEG) precipitation for macroprolactin screening, as well as the incidence and clinical characteristics of Chinese patients with macroprolactinemia. In this study, 94 patients with HPRL and 206 healthy individuals were included. Gel filtration chromatography (GFC), PEG precipitation, and UF were used to screen for macroprolactin, and chemiluminescence was used to determine the prolactin levels. The detected incidence of macroprolactinemia in the patients with HPRL was 7.45% (7/94, GFC) and 5.32% (5/94, PEG precipitation). Patients with macroprolactinemia usually present with atypical clinical symptoms, moderately increased prolactin levels, and negative or microadenoma-positive pituitary images. In addition, the recovery of monomeric prolactin by PEG precipitation and UF was significantly correlated to that of GFC (r PEG = 0.493, P < 0.001; r UF = 0.226, P = 0.014), with a higher correlation coefficient between PEG precipitation and GFC. Furthermore, PEG precipitation had a smaller variation (95% confidence interval [CI]: −35.77% to 18.34%) than UF in monomeric prolactin recovery and substantial diagnostic consistency with GFC (Cohen's kappa coefficient = 0.647). The proportion of monomeric prolactin in patients with HPRL did not change significantly between the two visits within one year (P > 0.05). The incidence of macroprolactinemia in Chinese patients with HPRL is low in the present study. Based on our analysis, we recommend that only patients who are clinically suspected of having macroprolactinemia should be screened using PEG precipitation.