title: Rapid elimination by glomerular filtration of free prostate specific antigen and human kallikrein 2 after renal transplantation.
abstract: OBJECTIVE
  The low molecular mass and short half-life of free (f) prostate specific antigen (PSA) implies elimination from blood by glomerular filtration. In addition, patients with terminal renal failure have increased fPSA in serum but there have been sparse data reported on the rates and pathways of elimination of PSA complexes and human kallikrein 2 (hK2). We studied glomerular filtration dependent elimination of fPSA and hK2 in patients with renal insufficiency undergoing successful renal transplantation.
  
  
  METHODS
  We studied 14 patients with immediate onset of renal function after renal transplantation. Blood samples were obtained before and at regular intervals up to 160 hours after transplanted kidney reperfusion. Measurements of fPSA, total PSA and hK2 were performed with immunofluorometric assays and complexed PSA was determined by a chemiluminiscence assay. Glomerular filtration rates were monitored by analyzing serum creatinine and cystatin C. NONMEM, a multivariate pharmacokinetic approach, was used to determine the elimination rates of fPSA and hK2 after renal transplantation.
  
  
  RESULTS
  Serum fPSA and hK2 but not PSA complexes, decreased rapidly after renal transplantation. Significant reductions in fPSA and hK2 were observed after only 16 and 8 hours, respectively. fPSA and hK2 showed similar elimination patterns, decreasing to 42% and 44% of their original levels compared to cystatin C, which was at 44% after 160 hours. The median half-lives of fPSA and hK2 were 17.4 and 11.5 hours, respectively.
  
  
  CONCLUSIONS
  These results verify the hypothesis that fPSA and hK2 are eliminated from the blood circulation by glomerular filtration and severe renal failure influences the levels of the 2 proteins in serum.
authors.affiliation: Department of Nephrology and Transplantation, Lund University, University Hospital, Malmö, Sweden. laila.bruun@klkemi.mas.lu.se
authors.forename: Laila
authors.initials: L
authors.lastname: Bruun
authors.forename: Henrik
authors.initials: H
authors.lastname: Ekberg
authors.forename: Thomas
authors.initials: T
authors.lastname: Bjørk
authors.forename: Hans
authors.initials: H
authors.lastname: Lilja
authors.forename: Peter
authors.initials: P
authors.lastname: Høglund
authors.forename: Anders
authors.initials: A
authors.lastname: Christensson
mesh_terms: D000368:Aged; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D013997:Time Factors; D020840:Tissue Kallikreins / Q000097:blood*
chemical_list: D020840:Tissue Kallikreins; D017430:Prostate-Specific Antigen