The natural history of macroprolactinaemia

Abstract

Objective: Macroprolactinaemia is a condition in which serum prolactin (PRL) consists mainly of large molecular weight PRL (macroPRL). The aim of this study was to examine the natural history of macroprolactinaemia. Design and participants: Six hundred and fifty-four hospital workers participated in this study, including 27 subjects with macroprolactinaemia and 627 controls. MacroPRL and serum PRL concentrations were evaluated over a 4-year period. The ratio of macroPRL was examined by the polyethylene glycol (PEG) method and gel filtration chromatography. IgG-bound PRL and anti-PRL autoantibodies were examined by protein G and 125 I-PRL binding studies respectively. Results: Over the 4 years of the study, all 27 macroprolactinaemic subjects had persistent macroprolactinaemia without the development of raised free PRL, while none of the 627 controls developed macroprolactinaemia. The ratios of PEG-precipitable PRL and IgG-bound PRL did not significantly change, but 125 I-PRL binding ratios significantly increased. As a whole, total and free serum PRL concentrations did not significantly change in subjects with macroprolactinaemia over the 4-year period. However, hyperprolactinaemia developed in five of the 18 macroprolactinaemic subjects who were initially normoprolactinaemic along with an increase in anti-PRL autoantibody titres. One of the remaining nine macroprolactinaemic subjects who were initially hyperprolactinaemic showed a decrease in serum PRL concentrations, which occurred concomitantly with a decrease in the anti-PRL autoantibody titre. Conclusions: Macroprolactinaemia may develop before middle age and is likely a chronic condition leading to hyperprolactinaemia.

The effect of oral contraception on macroprolactin levels in women with macroprolactinemia: A pilot study

“…This observation is in agreement with the previous findings of other authors [18,19] and indicates that big-big prolactin levels remain stable over time.…”

Serum Prolactin and Macroprolactin Levels among Outpatients with Major Depressive Disorder Following the Administration of Selective Serotonin-Reuptake Inhibitors: A Cross-Sectional Pilot Study

“…Macroprolactinemia is defined as a condition in which macroprolactin—which has a molecular mass of >150 kDa and, unlike monomeric PRL, has no action in the human body—is predominantly present in the serum [a PEG-precipitated PRL level greater than 52.8% (mean+2SD) was defined as macroprolactinemia in this study] [15,19]. The prevalence of macroprolactinemia has been estimated at 10–46% in patients with hyperprolactinemia [20–26].…”

Importance of macroprolactinemia in hyperprolactinemia

“…A number of studies have shown that PEG induced precipitation of macroprolactin in serum sample represents a simple, inexpensive, accessible, rapid and reproducible screening technique for hyperprolactinemic sera [19,26,27]. The method is based on different precipitation of proteins according to their molecular weight and solubility in different concentrations of PEG solution.…”

“…It has been generally accepted that a PEG-precipitation ratio greater than 60% (recovery less than 40%) is the cut-off value for the diagnosis of macroprolactinemia. This is because there is no a clear-cut value of "substantial increase", but conventionally a diagnosis of macroprolactinemia is made when more than 30-60% of PRL is in 11 the macroprolactin form of GFC [6,9,24,[26][27][28]. Precipitation with PEG is a widely used screening test for macroprolactin and is easily performed in clinical laboratories.…”