Clinical utility of an automated immunochemiluminometric thyroglobulin assay in differentiated thyroid carcinoma.
BACKGROUND
Thyroglobulin (Tg) measurements are important in the follow-up of patients with differentiated thyroid carcinoma (DTC). We evaluated the analytical and clinical performance of a new automated immunochemiluminometric assay for Tg (Tg-ICMA; Nichols Advantage Tg; Nichols Institute Diagnostics).


METHODS
We used the Tg-ICMA to measure Tg concentrations in serum samples from 110 Tg antibody-negative DTC patients undergoing thyroid-hormone suppression therapy. Disease state at the time of measurement was assessed on the basis of routine follow-up data. We compared the clinical performance of this assay with the routinely used IRMA (ELSA-hTG; CIS Bio International).


RESULTS
The detection limit and functional sensitivity of the Tg-ICMA, based on direct calibration to CRM-457, were 0.05 and 0.6 microg/L, respectively. No Tg-IRMA-positive cases were missed by the Tg-ICMA. Tg was measurable by Tg-ICMA (0.6-8.6 microg/L) but undetectable by Tg-IRMA (<1.5 microg/L) in 12 patients (11%). Clinical data showed evidence of disease in 4 of 12 patients (33%).


CONCLUSIONS
The Tg-ICMA is a sensitive and reproducible assay for identifying patients in follow-up for DTC with evidence of disease, but uncertainty remains with regard to interpreting findings of measurable serum Tg in patients with no evidence of disease. Follow-up data are required to determine the predictive value of these isolated Tg results. New concepts, i.e., serial Tg measurements and risk stratification of patients, need to be tested to confirm the applicability of this assay for clinical practice.
Persoon
Adrienne C M
AC
Department of Endocrinology, University Medical Centre Groningen, University of Groningen, The Netherlands.
Van Den Ouweland
Johannes M W
JM
Wilde
Juergen
J
Kema
Ido P
IP
Wolffenbuttel
Bruce H R
BH
Links
Thera P
TP
D001322:Autoanalysis; D005260:Female; D006801:Humans; D007118:Immunoassay; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000473:pathology
D013954:Thyroglobulin