Clinical Chemistry, Vol 42, 766-770, Copyright © 1996 by American Association for Clinical Chemistry

ELISA for thyroglobulin in serum: recovery studies to evaluate autoantibody interference and reliability of thyroglobulin values

M Erali, RB Bigelow and AW Meikle
Associated Regional and University Pathologists, Salt Lake City, UT, USA.

An ELISA for measuring thyroglobulin (Tg) in serum was developed with polyclonal antibodies to Tg on the solid phase and two monoclonal antibodies to Tg as the second antibodies. The assay has a detection limit of 1 microgram/L, a within-run imprecision (CV) of <7%, and a between-run CV of < 10%. Parallelism of the assay was shown in dilution studies, in which the percent observed/expected values for n = 5 autoantibody-containing samples gave a mean of 99% (SD 13.1 %); for n = 5 samples with undetectable autoantibody concentrations, the mean was 103% (SD 11.8%). The correlation of the ELISA with an RIA for Tg in 46 normal samples was ELISA = 1.11(RIA) + 0.52, S y/x = 2.23, SD intercept = 0.54, SD slope = 0.03, range = 0 to 53 micrograms/L, r = 0.980. Comparison of the ELISA with a reference laboratory RIA for 29 clinical samples gave a correlation of: ELISA = 1.53(RIA) - 0.48, S y/x = 9.00, SD intercept = 2.19, SD slope = 0.10, range = 0 to 98 micrograms/L, r = 0.950. To provide additional information concerning the reliability of the Tg measurement in samples containing autoantibodies to Tg, we developed a procedure for determining the percent recovery. A percent recovery greater than or equal to 80% indicates minimal interference by autoantibodies in this assay. The assay is straightforward to perform, results can be posted within 8 h, and the routinely good recovery of Tg in the presence of Tg autoantibodies indicates minimal autoantibody interference in this assay.

The following articles in journals at HighWire Press have cited this article:

				C. Massart and D. Maugendre Importance of the Detection Method for Thyroglobulin Antibodies for the Validity of Thyroglobulin Measurements in Sera from Patients with Graves Disease Clin. Chem., January 1, 2002; 48(1): 102 - 107. [Abstract] [Full Text] [PDF]

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