title: Macroprolactin does not contribute to elevated levels of prolactin in patients on renal replacement therapy.
abstract: 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.
  
  
  METHODS
  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.
  
  
  METHODS
  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 < 50% were identified as having macroprolactin isoforms.
  
  
  RESULTS
  The serum and supernatant PRL levels of CRF patients were significantly higher than those of the control group (P < 0.001). The serum PRL levels of HD and CAPD patients were significantly higher than those of the RT patients (P < 0.001). The serum PRL levels of the RT patients and the control group did not differ significantly (P > 0.05). A moderate correlation was found between PRL and creatinine levels (r = 0.609, P < 0.001).
  
  
  CONCLUSIONS
  The hyperprolactinaemia seen in renal replacement therapy is not associated with the presence of macroprolactin isoforms but with the decline in renal function.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Marmara University School of Medicine, Istanbul, Turkey.
authors.forename: Dilek
authors.initials: D
authors.lastname: Yavuz
authors.forename: Güler
authors.initials: G
authors.lastname: Topçu
authors.forename: Cetin
authors.initials: C
authors.lastname: Ozener
authors.forename: Sema
authors.initials: S
authors.lastname: Akalin
authors.forename: Onder
authors.initials: O
authors.lastname: Sirikçi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000097:blood; D005260:Female; D006801:Humans; D007118:Immunoassay; D007676:Kidney Failure, Chronic / Q000378:metabolism* / Q000628:therapy; D016030:Kidney Transplantation; D049449:Luminescence; D008297:Male; D008875:Middle Aged; D010531:Peritoneal Dialysis, Continuous Ambulatory; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D006435:Renal Dialysis; D018709:Statistics, Nonparametric
chemical_list: C060678:prolactin, polymeric; D011388:Prolactin; D003404:Creatinine