Macroprolactin does not contribute to elevated levels of prolactin in patients on renal replacement therapy

Summary Objective Three molecular forms of PRL with molecular weights of 23, 50–60 and > 100 kDa have been defined. The high‐molecular‐weight forms are called macroprolactin. Different immunoassays produce varyingly elevated results with macroprolactin‐containing sera. The kidneys are reported to clear 25% of PRL from the circulation. Hyperprolactinaemia is seen in 20–75% of patients with chronic renal failure (CRF). PRL clearance rate has been reported to be reduced in CRF and the resulting hyperprolactinaemia is due to reduced renal function. Patients To determine the contribution of macroprolactinaemia to elevated PRL levels in CRF, 91 patients receiving haemodialysis (HD), continuous ambulatory peritoneal dialysis (CAPD) and renal transplantation (RT) therapies and 72 control subjects were included in the study. Measurements Serum PRL levels were measured by a sandwich immunoassay with electrochemical detection. Following polyethylene glycol (PEG) precipitation, recovery ratios were calculated and samples with a recovery of