Interference in triiodothyronine (T3) analysis on the Immuno 1 Analyzer.
OBJECTIVE
To evaluate the interference in Triiodothyronine (T3) analysis on the Immuno 1 Analyzer.


METHODS
We analyzed 686 samples for T3 using the Miles Technicon Immuno 1 Analyzer. We compared the results of 318 samples with those given by radioimmunoassay (RIA) and the remaining 368 results with those given by the Ciba-Corning ACS 180 analyzer.


RESULTS
On the Immuno 1 correlated with those by RIA or chemiluminescence immunoassay. However, results on eight patients by the Immuno 1 method were anomalously elevated. We attempted to find and eliminate the cause of the interference on the Immuno 1. Although the method uses an alkaline phosphatase labelled T3 analog and fluoresceinated monoclonal antibody, serum binding of fluorescein or alkaline phosphatase did not appear to be the major causes of the interference. Ethanol extraction of samples followed by reconstitution in zero calibrator was the only reliable way to eliminate the interference.


CONCLUSIONS
The Immuno 1 assay was more prone to interference than other methods. Until it is reformulated, we recommend that users assay ethanol extracts of samples with unexpectedly high T3.
Wang
T
T
Department of Clinical Biochemistry, University of Toronto, Ontario, Canada.
Wan
B S
BS
Makela
S K
SK
Ellis
G
G
D000469:Alkaline Phosphatase / Q000737:chemistry; D000818:Animals; D000906:Antibodies / Q000737:chemistry; D005069:Evaluation Studies as Topic; D005189:False Positive Reactions; D006801:Humans; D006854:Hydrocortisone / Q000737:chemistry / Q000276:immunology; D007118:Immunoassay / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D007202:Indicators and Reagents; D007457:Iodine Radioisotopes; D051379:Mice; D013972:Thyrotropin / Q000737:chemistry; D014284:Triiodothyronine / Q000032:analysis* / Q000737:chemistry / Q000276:immunology*
D000906:Antibodies; D007202:Indicators and Reagents; D007457:Iodine Radioisotopes; D014284:Triiodothyronine; D013972:Thyrotropin; D000469:Alkaline Phosphatase; D006854:Hydrocortisone