A New Method of Using Polyethylene Glycol (PEG) Precipitation of Macroprolactin to Detect Genuine Hyperprolactinemia

Abstract

The most commonly used method of polyethylene glycol (PEG) precipitation for macroprolactinemia (MP) screening has some significant drawbacks. The aim of this study was to establish a new method using PEG for precipitation of macroprolactin (macroPRL) to detect genuine hyperprolactinemia (genuine HP). The optimal PEG concentration for precipitation and the effect of PEG on the precipitation of PRL were analyzed to establish and optimize our PEG precipitation method. The PRL recovery rate and genuine HP detection rate were compared between our method and MP screening method. About 25% PEG6000 was determined to be the optimal PEG concentration for precipitation. Along with an increase in protein concentration in the PRL calibration solution, the PRL recovery rate after precipitation decreased gradually. The PRL recovery rate increased when the precipitation was carried out with diluted PRL calibration solution; the recovery rate reached greater than 90% after a 5-fold dilution of the calibration solution. The genuine HP detection rate and PRL recovery rate using our diluted serum PEG precipitation method were significantly higher than those obtained with the MP screening method. Our method successfully detected 31 cases of genuine HP, which was significantly higher than the detection rate obtained using the MP screening method (25 cases; P < 0.001). Precipitation using 5-fold diluted serum with 25% PEG6000 can effectively reduce the macroPRL concentration, increasing the PRL recovery rate and detection rate of genuine HP after precipitation, which is an effective and convenient method for the detection of genuine HP.