Spuriously high thyrotropin values due to anti-thyrotropin antibodies in adult patients.
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.
Verhoye
Eline
E
Department of Clinical Chemistry, AZ St-Jan, Bruges, Belgium.
Van den Bruel
Annick
A
Delanghe
Joris R
JR
Debruyne
Evi
E
Langlois
Michel R
MR
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
D018828:Immunoglobulins, Thyroid-Stimulating; D011989:Receptors, Thyrotropin; D011092:Polyethylene Glycols; D013972:Thyrotropin