ORIGINAL ARTICLES 

The Quarterly Journal of Nuclear Medicine 2002 December;46(4):319-22

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

High-sensitive 2nd generation thyroglobulin immunoradiometric assay. Clinical application in differentiated thyroid cancer management

Giovanella L., Ceriani L., Garancini S

Laboratory of Endocrinology and Thyroid Unit Department of Nuclear Medicine University Hospital “Ospedale di Circolo e Fondazione Macchi” Varese, Italy

Back­ground. Cir­cu­lating ­human thy­ro­glob­ulin (hTG) meas­ure­ments ­have a piv­otal ­role in the man­age­ment of ­patients ­affected by dif­fer­en­tiated thy­roid ­cancer (DTC). The ­present ­study was under­taken by ­employing a new devel­oped ­high-sen­si­tive hTG immu­nor­a­di­o­metric ­assay to eval­uate its diag­nostic per­for­mance in ­patients ­affected by rad­i­cally ­cured and ­relapsing DTC and to set the ­most appro­priate cut-off ­point for DTC man­age­ment.
­Methods. We ret­ro­spec­tively ­selected 172 ­patients ­without ­signs of recur­rence ­after pri­mary treat­ment and 45 ­patients ­with recur­rences ­from DTC. ­Serum sam­ples ­were col­lected ­during l-thy­roxine (T4) sup­pres­sive ­therapy (onT4) and 4 ­weeks ­after T4 with­drawal (­offT4) and hTG meas­ured by a spe­cific ­high-sen­si­tive ­IRMA ­assay (­DYNOtest® Tg-­plus, ­BRAHMS Diag­nos­tica ­GmbH, ­Berlin, Ger­many). ­Sera ­showing the pres­ence of ­AbhTG or hTG-­recovery ­less ­than 80% ­were ­excluded ­from the ­study. ROC ­curve anal­ysis was per­formed to ­select the ­best cut-off ­levels and diag­nostic per­for­mance of the ­marker eval­u­ated.
­Results. By ­using onT4 cut-off ­level of 0.2 ng/mL and ­offT4 cut-off ­level of 0.5 ng/mL we ­obtained a sen­si­tivity/spec­i­ficity/accu­racy pro­file of 0.91/0.98/0.96 and 0.98/0.97/0.97, respec­tively. We ­found onT4-hTG ­false-neg­a­tive ­results in 4 ­patient ­with ­local recur­rence (n=2) or cer­vical ­lymph-­node metas­tasis (n=2) ­while ­only 1 ­patient ­with ­local recur­rence ­showed neg­a­tive ­offT4-hTG. How­ever, onT4 and ­offT4-hTG ­false-neg­a­tive ­results ­were ­observed in 9 and 5 ­patients ­when 1.0 ng/mL cut-off ­level was ­employed.
Con­clu­sions. On the ­basis of our ­data, we con­clude ­that ­DYNOtest® Tg-­plus ­assay is ­very effec­tive and accu­rate in the eval­u­a­tion of ­patients ­with DTC.