Document Detail

Undetectable thyroglobulin in patients with differentiated thyroid carcinoma and residual radioiodine uptake on a postablation whole-body scan.
MedLine Citation:
PMID:  21220971     Owner:  NLM     Status:  In-Process    
AIM: To assess the impact of laboratory interferences and pitfalls in producing falsely undetectable Tg in differentiated thyroid carcinoma (DTC) patients with residual iodine-avid thyroid tissue on a posttreatment whole-body scan (PT-WBS).
METHODS: From 298 consecutive patients with histologically proven DTC, 47 patients (16%) with undetectable serum Tg but residual ¹³¹I uptake on a PT-WBS were selected. Interferences from antithyroglobulin antibodies (TgAb), heterophile antibodies, and hook-effects were screened; in the remaining samples, serum Tg was measured in 3 different immunoassays.
RESULTS: Of 47 patients, 11 (23%) showed interference from either thyroglobulin antibodies (n = 10) or heterophile antibodies (n = 1). Among the 36 remaining patients, 18 showed detectable Tg levels after retesting using a different immunoassay, whereas the remaining 18 patients also showed detectable Tg levels in a third Tg immunoassay. However, only 7 patients showed a detectable Tg in both secondarily used assays. Tg levels remained undetectable in all methods in 9 patients (19%) even after extensive laboratory work-up and despite the presence of ¹³¹I-avid tissue found in PT-WBS.
CONCLUSIONS: A careful assessment of interferences in Tg measurement significantly reduced the occurrence of undetectable Tg among patients with ¹³¹I uptake in PT-WBS. However, such extensive assessment is difficult in clinical practice and one-fifth of patients still had undetectable Tg in multiple assays despite an intensive laboratory work-up. A benchmark between ¹³¹I imaging and Tg measurement authenticates the interpretation of Tg measurements and, consequently, remains of pivotal value by authenticating the use of serum Tg during further follow-up of DTC patients.
Luca Giovanella; Sergio Suriano; Luca Ceriani; Frederik Anton Verburg
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Clinical nuclear medicine     Volume:  36     ISSN:  1536-0229     ISO Abbreviation:  Clin Nucl Med     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-01-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7611109     Medline TA:  Clin Nucl Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  109-12     Citation Subset:  IM    
Department of Nuclear Medicine and Thyroid Centre, Oncology Institute of Southern Switzerland, Bellinzona, Switzerland.
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