title: Spuriously high thyrotropin values due to anti-thyrotropin antibodies in adult patients.
abstract: BACKGROUND
  Three adult patients presented with unexpectedly high thyrotropin (TSH) concentrations that were discordant with clinical and biochemical findings of euthyroid or hyperthyroid status.
  
  
  METHODS
  Antibody interference in the TSH immunoassay (Roche) was investigated by polyethylene glycol (PEG)-pretreatment, heterophilic blocking tube (HBT)-pretreatment, rheumatoid factor (RF) testing, immunofixation, protein A adsorption, and gel filtration chromatography (GFC).
  
  
  RESULTS
  PEG-precipitation yielded<20% recovery of serum TSH, whereas HBT-pretreatment did not decrease TSH test results. RF-testing and immunofixation were negative. Protein A adsorption and GFC demonstrated the presence of TSH-immunoglobulin complexes in serum.
  
  
  CONCLUSIONS
  Interference by TSH-immunoglobulin complexes should be ruled out in euthyroid and hyperthyroid patients presenting with inappropriately increased or non-suppressed TSH values.
authors.affiliation: Department of Clinical Chemistry, AZ St-Jan, Bruges, Belgium.
authors.forename: Eline
authors.initials: E
authors.lastname: Verhoye
authors.forename: Annick
authors.initials: A
authors.lastname: Van den Bruel
authors.forename: Joris R
authors.initials: JR
authors.lastname: Delanghe
authors.forename: Evi
authors.initials: E
authors.lastname: Debruyne
authors.forename: Michel R
authors.initials: MR
authors.lastname: Langlois
mesh_terms: D000328:Adult; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods* / Q000592:standards; D018828:Immunoglobulins, Thyroid-Stimulating / Q000097:blood*; D008875:Middle Aged; D011092:Polyethylene Glycols / Q000737:chemistry; D011233:Precipitin Tests; D011989:Receptors, Thyrotropin / Q000276:immunology; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000097:blood*; D055815:Young Adult
chemical_list: D018828:Immunoglobulins, Thyroid-Stimulating; D011989:Receptors, Thyrotropin; D011092:Polyethylene Glycols; D013972:Thyrotropin