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J Clin Endocrinol Metab. 2013 Jan;98(1):153-60. doi: 10.1210/jc.2012-2369. Epub 2012 Nov 8.

Serum antithyroglobulin antibodies interfere with thyroglobulin detection in fine-needle aspirates of metastatic neck nodes in papillary thyroid carcinoma.

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1
Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Pungnap-dong, Songpa-gu, Seoul 138-736, Korea.

Abstract

CONTEXT:

It is recommended to measure thyroglobulin (Tg) levels in the needle washout fluids from fine-needle aspirations (FNAs) in patients with papillary thyroid carcinoma (PTC) who have ultrasonographically suspicious metastatic lymph nodes (LNs). However, it is not clear whether serum anti-Tg antibodies (TgAbs) interfere with the detection of Tg in needle washout fluids from FNAs (FNA-Tg).

OBJECTIVE:

The objective of the study was to evaluate the influence of serum TgAbs on FNA-Tg detection.

DESIGN AND SETTINGS:

This retrospective observational cohort study enrolled 207 patients with conventional PTC in whom FNA-Tg values had been measured. All patients initially underwent total thyroidectomy and remnant ablation. FNA-Tg levels were measured from ultrasonographically suspicious metastatic LNs of 0.5 cm or greater in the longest diameter.

RESULTS:

From 207 patients, 263 LNs were evaluated. Final histopathology was available for 92 LNs, of which 88 (96%) were malignant. FNA-Tg levels were lower in the LNs from serum TgAb-positive patients than in those from TgAb-negative patients (P < 0.001). In four of 13 metastatic LNs from TgAb-positive patients, the FNA-Tg levels were below 10 μg/liter including one in which both FNA-Tg and serum-stimulated Tg levels were below 1 μg/liter and stained positively for Tg in pathology. There was also one malignant LN with negative for FNA-Tg, serum-stimulated Tg, and serum TgAb but that nonetheless stained intensely for Tg. However, there were no malignant LNs with both negative cytology and negative FNA-Tg. A diagnosis based on FNA-Tg had a lower sensitivity and negative predictive value in the TgAb-positive group than in the TgAb-negative group.

CONCLUSION:

FNA-Tg measurement is highly reliable in the diagnosis of neck metastases in PTC patients, even in cases of negative-stimulated Tg or positive TgAb. However, high-serum TgAb levels could interfere with FNA-Tg measurements and thereby result in falsely low FNA-Tg levels.

PMID:
23144473
DOI:
10.1210/jc.2012-2369
[Indexed for MEDLINE]

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