Prevalence and causes of abnormal PSA recovery

Clin Chem Lab Med. 2018 Jan 26;56(2):341-349. doi: 10.1515/cclm-2017-0246.

Abstract

Background: Prostate-specific antigen (PSA) test is of paramount importance as a diagnostic tool for the detection and monitoring of patients with prostate cancer. In the presence of interfering factors such as heterophilic antibodies or anti-PSA antibodies the PSA test can yield significantly falsified results. The prevalence of these factors is unknown.

Methods: We determined the recovery of PSA concentrations diluting patient samples with a standard serum of known PSA concentration. Based on the frequency distribution of recoveries in a pre-study on 268 samples, samples with recoveries <80% or >120% were defined as suspect, re-tested and further characterized to identify the cause of interference.

Results: A total of 1158 consecutive serum samples were analyzed. Four samples (0.3%) showed reproducibly disturbed recoveries of 10%, 68%, 166% and 4441%. In three samples heterophilic antibodies were identified as the probable cause, in the fourth anti-PSA-autoantibodies. The very low recovery caused by the latter interference was confirmed in serum, as well as heparin- and EDTA plasma of blood samples obtained 6 months later. Analysis by eight different immunoassays showed recoveries ranging between <10% and 80%. In a follow-up study of 212 random plasma samples we found seven samples with autoantibodies against PSA which however did not show any disturbed PSA recovery.

Conclusions: About 0.3% of PSA determinations by the electrochemiluminescence assay (ECLIA) of Roche diagnostics are disturbed by heterophilic or anti-PSA autoantibodies. Although they are rare, these interferences can cause relevant misinterpretations of a PSA test result.

Keywords: autoantibodies; heterophilic antibodies; immunoassay; prostate; prostate-specific antigen (PSA); recovery.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Autoantibodies / blood*
  • Cell Line, Tumor
  • Diagnostic Errors
  • Enzyme-Linked Immunosorbent Assay / methods
  • Humans
  • Male
  • Middle Aged
  • Prostate-Specific Antigen / blood*
  • Prostatic Neoplasms / diagnosis

Substances

  • Autoantibodies
  • Prostate-Specific Antigen