Thyroglobulin Antibodies and Tumor Epitope-Specific Cellular Immunity in Papillary Thyroid Cancer

Papillary thyroid carcinoma (PTC) is characterized by T cell infiltration and frequently by the presence of anti-thyroglobulin antibodies (TgAbs). The role of cellular immunity and of TbAbs in this context is a matter of debate. The aim of our study was to correlate the presence of TgAbs, tumor epitope-specific T cells and the clinical outcome of PTC patients. We studied n=183 consecutive patients with a diagnosis of PTC which were treated with total thyroidectomy plus 131I ablation. During a follow-up of in mean 97 months, most of the PTC patients had no signs of tumor relapse (n=157 patients). In contrast, one patient had serum Tg levels above the detection limit and<1 ng/ml, two patients Tg serum levels≥1 ng/ml and<2 ng/ml and n=23 patients had Tg serum levels≥2 ng/ml. Morphological signs of tumor recurrence were seen in 14 patients; all of these patients had serum Tg levels≥2 ng/ml. Importantly, with the exception of one patient, all TgAb positive PTC patients (n=27) had no signs of tumor recurrence as the serum Tg levels were below the assays functional sensitivities. Tetramer analyses revealed a higher number of tumor epitope-specific CD8+T cells in TgAb positive patients compared to TgAb negative PTC patients. In summary, we show that the occurrence of TgAbs may have an impact on the clinical outcome in PTC patients. This might be due to a tumor epitope-specific cellular immunity in PTC patients.

Prognostic value of postoperative anti-thyroglobulin antibody in patients with differentiated thyroid cancer

Purpose

Postoperative thyroglobulin (Tg) generally serves as a biomarker to monitor the recurrence or persistence of differentiated thyroid cancer (DTC), whereas it constrains to interference from anti-thyroglobulin antibody (TgAb). This study aimed to determine the value of postoperative TgAb as a surrogate for monitoring tumor status in DTCs with positive TgAb after successful radioactive iodine (RAI) remnant ablation.

Methods

We retrospectively enrolled DTC patients with positive (≥40 IU/mL, Roche) postoperative TgAb measurements. An index of TgAb change (ΔTgAb) was defined to describe the TgAb decrease rate. DTC status was defined as either no evidence of disease (NED) or persistent/recurrent disease (PRD). Univariate and multivariate binary logistic analyses were used to identify the independent risk factors of PRD. Receiver operating characteristic (ROC) curves were performed to determine the optimal cutoff values of each risk factor, and DeLong's test was conducted to compare their predictive powers. Kaplan-Meier curves were used to assess the impact of different TgAb trends in the first year on progression-free survival.

Results

Of the 232 patients enrolled, the median diagnosis age was 34 years (range, 18-62 years), with a male-to-female ratio of 1:4.66 (41/191). Among them, after a median follow-up of 44 months (range, 4-128 months),183 (78.87%) patients were evaluated as NED, while the other 49 (21.12%) had either persistent (n = 25) or recurrent disease (n = 24). Multivariate regression showed that ΔTgAb (P < 0.001) and lymph node metastasis (LNM) rate (P = 0.009) were independently relevant to the presence of PRD, with optimal cutoff values of 47.0% and 35.1%, respectively. It is important to note that there is a high negative predictive value (96.93%) of ΔTgAb with the cutoff of 47.0%. DeLong's test showed that ΔTgAb alone and the combination of ΔTgAb and LNM rate were significantly greater than the isolated LNM rate (both P < 0.001) in predicting NED, while there was no statistical difference of the predictive power between ΔTgAb and the combination (P = 0.203). Additionally, patients with ΔTgAb >47.0% had longer progression-free survival than those with ΔTgAb ≤47.0% (not reached vs. 50 months, P < 0.001), and those with ΔTgAb >47.0% or negative conversion within the first year after RAI ablation had longer progression-free survival.

Conclusion

Our study suggested that ΔTgAb could serve as a valuable indicator of disease status in DTC patients with positive TgAb. A ΔTgAb of >47.0% is conducive to identify those with NED and may help to obviate their overtreatment. The decrease rate and negative conversion of TgAb in the first year were good predictors of disease-free survival in patients.

Predicting clinical outcomes of patients with serum thyroglobulin antibodies after thyroidectomy for differentiated thyroid cancer: a retrospective study from a UK regional center

BACKGROUND

Twenty-twenty-five percent of patients with differentiated thyroid cancer (DTC) can have elevated thyroglobulin antibodies (TgAb). The study aimed to find any prognostic significance of elevated TgAb during follow-up.

METHODS

Ten-year retrospective study from a tertiary center including 79 patients with raised TgAb after total/staged thyroidectomy for DTC. We identified patients with stable (7.6%), increasing (15%) and decreasing levels of TgAb (77.2%); groups 1, 2 and 3 respectively. During follow-up we analyzed TgAb in subcategories by TgAb trend (>50% rise, <50% rise, >50% decline, <50% decline, positive to negative/normalization, negative to positive and stable levels), gender, age, surgery, autoimmune disease, histology, RAI uptake, distant metastases, and recurrence.

RESULTS

The incidence of raised TgAb levels was 33.2%, with female predominance. No connection was identified regarding other parameters. 11.4% had distant metastases. The highest mean maximum levels of TgAb was in group 2 (1918.75 IU/mL) and the lowest in group 3 (412.70 IU/mL). The recurrence rate changed significantly between the 3 groups: 50% in group 1, 75% in group 2, and 25% in group 3 (P=0.002). Recurrence rates decreased to 15% in the subcategory where TgAb became negative/normal from positive (P=0.0001). In patients with a negative to positive TgAb level trend or >50% rise, recurrence rates were 100% (P=0.041) and 70% (P=0.012) respectively.

CONCLUSIONS

Patients with increasing TgAb levels during follow-up have a higher rate of recurrence, distinctly for those with negative to positive trend and >50% rise in TgAb. These patients need closer follow-up, and TgAb may be used as a dynamic follow-up marker.

Stimulated thyroglobulin and pre-ablation antithyroglobulin antibody products can predict the response to radioiodine therapy of TgAb-positive differentiated thyroid cancer patients: a retrospective study

Objective

We aimed to explore the predictive value of stimulated thyroglobulin (sTg) and pre-ablation antithyroglobulin (pa-TgAb) products for the effect of radioiodine therapy (RAIT) on TgAb-positive differentiated thyroid cancer (DTC) patients.

Methods

In this study, we enrolled 265 patients with TgAb-positive DTC who underwent RAIT after total thyroidectomy (TT). Based on the last follow-up result, the patients were divided into two groups: the excellent response (ER) group and the non-excellent response (NER) group. We analyzed the factors related to the effect of RAIT.

Results

The ER group consisted of 197 patients. The NER group consisted of 68 patients. For the univariate analysis, we found that the maximal tumor diameter, whether with extrathyroidal extension (ETE), bilateral or unilateral primary lesion, multifocality, preoperative TgAb (preop-TgAb), pa-TgAb, sTg × pa-TgAb, initial RAIT dose, N stage, and surgical extent (modified radical neck dissection or not), showed significant differences between the ER group and NER group (all p-values <0.05). The receiver operating characteristic (ROC) curves showed that the cutoff value was 724.25 IU/ml, 424.00 IU/ml, and 59.73 for preop-TgAb, pa-TgAb, and sTg × pa-TgAb, respectively. The multivariate logistic regression analysis results indicated that pa-TgAb, sTg × pa-TgAb, initial RAIT dose, and N stage were independent risk factors for NER (all p-values <0.05). For the Kaplan-Meier analysis of disease-free survival (DFS), the median DFS of the patients with sTg × pa-TgAb < 59.73 and initial RAIT dose ≤ 100 mCi was significantly longer than that of the patients with sTg × pa-TgAb ≥ 59.73 (50.27 months vs. 48.59 months, p = 0.041) and initial RAIT dose >100 mCi (50.50 months vs. 38.00 months, p = 0.030).

Conclusion

We found the sTg and pa-TgAb conducts is a good predictor of the efficacy of RAIT in TgAb-positive DTC patients. It can play a very positive and important role in optimizing treatment, improving prognosis, and reducing the burden of patients.

Thyroglobulin and thyroglobulin antibody: an updated clinical and laboratory expert consensus

OBJECTIVE

Thyroglobulin measurement is the cornerstone of modern management of differentiated thyroid cancer, with clinical decisions on treatment and follow-up based on the results of such measurements. However, numerous factors need to be considered regarding measurement with and interpretation of thyroglobulin assay results.

DESIGN

The present document provides an integrated update to the 2013 and 2014 separate clinical position papers of our group on these issues.

METHODS

Issues concerning analytical and clinical aspects of highly-sensitive thyroglobulin measurement will be reviewed and discussed based on an extensive analysis of the available literature.

RESULTS

Thyroglobulin measurement remains a highly complex process with many pitfalls and major sources of interference, especially anti-thyroglobulin antibodies, need to be assessed, considered and, when necessary, dealt with appropriately.

CONCLUSIONS

Our expert consensus group formulated 53 practical, graded recommendations for guidance on highly-sensitive thyroglobulin and TgAb in laboratory and clinical practice, especially valuable where current guidelines do not offer sufficient guidance.

Evolution of thyroid cancer biomarkers: from laboratory test to patients’ clinical management

Over the past three decades, laboratory medicine has significantly evolved thanks to technological advances made possible by new materials and evidence. Clinicians’ ongoing requests for powerful, rapid, and minimally invasive tests has led manufacturers to develop rapid, accurate, and sensitive tests that can increase diagnostic accuracy and improve follow-up, bringing laboratory medicine ever closer to personalized medicine. The aim of this study was to critically review the main problems of the current Tg and CT biomarkers for the diagnosis/monitoring of DTC and MTC, respectively, and to identify the advantages and challenges of using the new laboratory biomarkers in the clinical management of patients with differentiated and medullary thyroid cancer. Insufficient harmonization of Tg and CT assays and lack of interchangeability of laboratory results and cutoff values pose challenges for comparability and standardization of procedures and methods. New diagnostic and monitoring approaches such as PCT or the Tg doubling time have proven to be effective. Close collaboration between clinicians and laboratory specialists remains essential to translate the advantages and limitations of current assays into appropriate clinical interpretation criteria. Over the years, the journal Clinical Chemistry and Laboratory Medicine (CCLM) has taken many steps to develop advanced research and technology in the diagnosis and monitoring of tumor cancer and to help clinicians translate it into clinical practice.

Thyroglobulin antibodies: Trend over time and clinical impact in differentiated thyroid carcinoma with and without radioiodine ablation

INTRODUCTION

Thyroglobulin antibodies (TgAb) trend may be considered a surrogate marker for thyroglobulin in differentiated thyroid carcinoma. The aim of this study is to analyse, in cases with positive TgAb, trend over time and its relationship with response to treatment.

MATERIAL AND METHODS

Retrospective and descriptive study of 100 patients with differentiated thyroid carcinoma and positive TgAb (measured by electrochemoluminiscense) after thyroidectomy. Assessment of response to initial treatment was performed 6-24 months after surgery. Status at last follow-up was evaluated.

RESULTS

After the first year nearly half of the patients showed a reduction in TgAb levels ≥50%, in 91% of these patients, status at last follow up was excellent response (65%) or indeterminate response due to decreasing TgAb levels (26%). At first assessment, indeterminate responses were found in 49% of cases, without significant differences among initial risk of recurrence category or whether radioiodine ablation was performed. At last evaluation (median 53.5 months), 15% of ablated low-risk patients had an indeterminate response (due to declining TgAb), vs 62% in the non-ablated low-risk group (p 0.03). Median time to negativization for post-surgical TgAb levels<100UI/ml was 11 months [3-94] vs 31 months [8-119] for patients with TgAb≥100UI/ml (p 0.0003).

CONCLUSION

A reduction of ≥50% in TgAb levels during the first year correlated with favourable outcomes. Non-ablated patients and patients with higher levels of post-surgical TgAb may need a longer time to achieve negative conversion.

Indication for radioactive iodine in patients with papillary thyroid carcinoma without apparent disease after total thyroidectomy but with elevated antithyroglobulin antibodies

OBJECTIVE

To evaluate a criterion for the selective indication of radioactive iodine (RAI) based on the short-term behaviour of antithyroglobulin antibodies (TgAb) in patients with papillary thyroid carcinoma (PTC) who have negative thyroglobulin (Tg) and neck ultrasonography (US) without abnormalities after total thyroidectomy but elevated TgAb.

DESIGN

This was a prospective study that evaluated 216 patients with low- or intermediate-risk PTC who had nonstimulated Tg ≤ 0.2 ng/ml and no US abnormalities but elevated TgAb 3 months after thyroidectomy. RAI was not indicated in patients with negative TgAb or a >50% reduction in TgAb concentrations 6 months after initial assessment followed by a negative test or an additional reduction (also >50%) after 12 months.

RESULTS

Only two of the 114 patients who did not receive RAI developed recurrences; another 108 patients met the criterion of an excellent response to therapy in the last assessment and TgAb persisted in four patients but there was an additional reduction in their concentration during follow-up. Among the 102 patients who received RAI, post-therapy whole-body scanning (RxWBS) detected persistent disease in 8 (8%). Two of the 94 patients without persistent disease on RxWBS developed recurrences. In the last assessment, in the absence of additional treatment, 54/92 patients (58.7%) without structural recurrence had negative TgAb.

CONCLUSIONS

The indication for RAI can be based on the short-term behaviour of TgAb in patients with PTC and elevated TgAb after thyroidectomy who are not high risk and who do not have apparent disease (nonstimulated Tg ≤ 0.2 ng/ml and no US abnormalities).

Awareness of thyroid cancer among medical students: A questionnaire-based study

To investigate whether medical students acquire enough knowledge about thyroid cancer (TC). It was a cross-sectional study in a Chinese medical college based on a questionnaire about the knowledge of TC and thyroid self-examination. Medical students enrolled were grouped into preclinical medical students (PMS) and clinical medical students (CMS) according to their grades. A total of 337 questionnaires were distributed and 274 effective responses were collected with 129 from PMS and 145 from CMS. The percentage of thyroid self-examination in CMS was higher than that of PMS (55.8% vs 11.6%, p < 0.001). Generally, CMS had better comprehension of TC, including prognosis (97.2% vs 64.5%, p < 0.001), diagnosis (95.6% vs 33.1%, p < 0.001), and surgery indications (82.1% vs 58.1%, p = 0.001). There was no significant difference between PMS and CMS on the acquaintance of the risk factors. However, more CMS stated that the below 5% of thyroid nodules might turn malignant (45.5% vs 6.5%, p < 0.001), and more CMS suggested that people without nodules should receive TC screening tests (62.1% vs 41.9%, p = 0.001). Medical education on TC was effective in teaching clinical knowledge. Medical school should focus more on preclinical general health education and clinical practices education in the future.

Antithyroglobulin Antibody Variation During Follow-Up Has a Good Prognostic Value for Preoperative Antithyroglobulin Antibody-Positive Differentiated Thyroid Cancer Patients: A Retrospective Study in Southwest China

OBJECTIVE

Antithyroglobulin antibody (TgAb) is a potential tumour marker for detecting differentiated thyroid cancer (DTC) recurrence, but insufficient data have supported its clinical applications. Our study aimed to describe the changing trend of TgAb after surgery and identify the relationship between this trend and clinical outcomes.

PATIENTS AND METHODS

We reviewed the electronic records of 1,686 DTC patients who had undergone total thyroidectomy (TT) and radioactive iodine (¹³¹I) therapy at West China Hospital of Sichuan University from January 2015 to December 2017. Finally, 289 preoperative TgAb-positive DTC patients were included and divided into four subgroups depending on the clinical outcome: Group A (tumour free), Group B (uncertain), Group C (incomplete biochemical response), and Group D (structural disease). The patient demographics, tumour characteristics, operations, pathology reports, and all serological biomarkers were reviewed and compared, and the prognostic efficacy of TgAb was evaluated.

RESULTS

Among all 1,686 patients, 393 (23.65%) were TgAb positive (>40 IU/ml) preoperatively. The TgAb level in Group A decreased significantly after surgery and ¹³¹I therapy and stabilised at a low level after 1-2 years of ¹³¹I therapy. However, in the other three groups, the decrease in TgAb was not significant after treatment. Conversely, TgAb declined slowly and remained stable or increased. The variations in TgAb relative to the preoperative level of Group A were significantly larger than those of Groups B, C, and D at most time points of follow-up (p < 0.001). By receiver operating characteristic (ROC) analyses, the variations of TgAb > -77.9% at 6 months after ¹³¹I therapy (area under the curve (AUC) = 0.862; p < 0.001) and TgAb > -88.6% at 2 years after ¹³¹I therapy (AUC = 0.901; p < 0.001) had good prognostic efficacy in tumour-free survival. When the variation in TgAb > -88.6% at 2 years after ¹³¹I therapy was incorporated as a variable in the American Thyroid Association (ATA) categories, both intermediate- and high-risk patients also had a significantly increased chance of being tumour free (from 75.68% to 93.88% and 42.0% to 82.61%, respectively).

CONCLUSIONS

For preoperative TgAb-positive DTC patients, variations in TgAb > -77.9% at 6 months after ¹³¹I therapy and TgAb > -88.6% at 2 years after ¹³¹I therapy had good prognostic efficacy. Their incorporation as variables in the ATA risk stratification system could more accurately predict disease-free survival.

Investigating Antithyroglobulin Antibody As a Prognostic Marker for Differentiated Thyroid Cancer: A Meta-Analysis and Systematic Review

Background: Serum thyroglobulin (Tg) is used in the follow-up of patients with differentiated thyroid cancers (DTC), but the presence of antithyroglobulin antibodies (TgAbs) makes Tg measurements unreliable. TgAb decline after total thyroidectomy and persistent/increasing levels may indicate cancer persistence/recurrence. Hence, we aimed to determine whether TgAb might be a reliable prognostic marker for DTC. Methods: We conducted a meta-analysis and systematic review. A comprehensive literature search was performed to identify studies of patients with DTC with known TgAb status and prognostic outcomes in five databases (Medline, Embase, PubMed, Google Scholar, and Scopus). We used a random-effects model to calculate pooled odds ratios (ORs) and 95% confidence intervals (CIs) for TgAb status and its association with DTC prognosis. Results: After analysis of 34 studies, we found that TgAb+ patients have a higher risk of lymph node metastasis (OR = 1.18 [CI 1.47-2.25]) and cancer persistence/recurrence (OR = 2.78 [CI 1.55-4.98]) than TgAb- patients. However, no significant differences in mean/median tumor size, risk of extrathyroidal extension, tumor multifocality, and cancer mortality were found between the two groups. In a comparison of TgAb trends, patients with persistent/increasing TgAb levels were found to have a higher risk of cancer persistence/recurrence (OR = 9.90 [CI 4.36-22.50]) and cancer mortality (OR = 15.18 [CI 2.99-77]) than patients with decreasing TgAb levels. Conclusions: TgAb positivity and persistent/increasing trends were associated with compromised DTC prognosis. These results suggest that TgAb may be used as a prognostic marker in the follow-up of patients with DTC.

High Expression of Interleukin-12A and Its Association with the Clinicopathology and Prognosis of Differentiated Thyroid Cancer

BACKGROUND

The inflammatory microenvironment is closely related to the occurrence and development of cancer. Members of the interleukin-12 (IL-12) cytokine family play synergistic or antagonistic roles in the tumor microenvironment, in the form of classic heterodimers or newly discovered monomers or homodimers.

OBJECTIVE

The purpose of this study was to investigate the association between IL-12A and the clinicopathology and prognosis of differentiated thyroid cancer (DTC).

METHODS

A total of 101 pathologically confirmed DTC patients were included in this study. Immunohistochemistry was performed to assess IL-12A expression in DTC and corresponding paracancerous tissues. The associations of IL-12A with clinicopathology and prognosis were evaluated.

RESULTS

IL-12A was expressed in both normal thyroid tissues and DTC, but its expression level was significantly higher in DTC than in normal thyroid tissues (p < 0.001). IL-12A was positively correlated with tumor size (p = 0.027), risk stratification (p = 0.020), and TNM (Tumor-Node-Metastasis) stage (p = 0.024), but not with age, sex, pathological type, multifocality, extrathyroid extension, lymph node metastasis, and distant metastasis (all p > 0.05). Lymphocytic thyroiditis was found in 26/101 patients (25.7%), which was negatively associated with IL-12A expression (p = 0.018). Multivariate logistic regression analysis showed that risk stratification was the significant independent predictor of IL-12A expression. The rate of disease persistence or recurrence (P&R) was 13/101 (12.9%), and a positive relationship was found between IL-12A expression and P&R (p = 0.020). Disease-free survival was affected by factors such as tumor size, extrathyroid extension, tumor stage (T stage), and IL-12A expression, with p values of 0.006, 0.048, 0.002, and 0.012, respectively. Multivariate Cox proportional-hazards analysis showed that tumor size ≥2 cm (hazard ratio [HR] = 4.041 [95% CI: 1.144-14.274], p = 0.031) and high IL-12A expression (HR = 4.027 [95% CI 1.014-15.994], p = 0.049) were independent predictors of prognosis of DTC patients.

CONCLUSIONS

IL-12A is highly expressed in DTC and is associated with disease aggressiveness. In addition, IL-12A is an independent predictor of the outcome of DTC.

Positive thyroid antibodies and risk of thyroid cancer: A systematic review and meta-analysis

Previous studies assessing the association between thyroid antibodies and the risk of thyroid cancer (TC) have produced inconsistent results. The present study therefore conducted a meta-analysis of the available data. PubMed, Embase and the Cochrane Library were searched for the retrieval of relevant studies and a meta-analysis was conducted to systematically evaluate the association between positive thyroid antibodies and the risk of TC. This search identified 16 articles containing 17 studies on thyroglobulin antibodies (TgAb), which involved a total of 34,488 patients. Positive TgAb was associated with an increased risk of TC [odds ratio (OR)=1.93, 95% confidence interval (CI)=1.64–2.27, I²=67.2%]. Whether to adjust for confounding factors (gender and thyroid nodule number) was the main cause of heterogeneity. A stronger association between positive TgAb and an increased risk of TC was identified in the studies with an unadjusted thyroid nodule number (OR=2.14, 95% CI=1.82–2.52), as compared to those with an adjusted thyroid nodule number (OR=1.61, 95% CI=1.29–2.00; P=0.04). In addition, 12 studies on thyroid peroxidase antibodies (TPOAb) involving 30,007 patients were included. Positive TPOAb was associated with an increased risk of TC (OR=1.50, 95%CI=1.16–1.95, I²=83.0%). No significant heterogeneity was observed in the PTC group. Positive TgAb is an independent risk factor for TC. The association between positive TPOAb and increased risk of TC needs to be further studied.

Clinical Applicability of Low Levels of Thyroglobulin Autoantibodies as Cutoff Point for Thyroglobulin Autoantibody Positivity

BACKGROUND

Thyroglobulin (Tg) is an established tumor marker in differentiated thyroid carcinoma (DTC). However, Tg assays can be subject to interference by autoantibodies against Tg (TgAbs). No clinical consensus exists on the cutoff value of TgAb positivity and its relationship to Tg assay interference. The aims of this study were to investigate the most applicable cutoff value for TgAb positivity in clinical practice and to evaluate whether tumor characteristics differ between TgAb+ and TgAb- patients during ablation therapy using the manufacturer's cutoff (MCO) and institutional cutoff (ICO).

METHODS

This single-center cohort study included 230 DTC patients diagnosed between January 2006 and December 2014. Serum Tg and TgAbs were measured with the Tg-IRMA (Thermo Fisher Scientific) and ARCHITECT Anti-Tg (Abbott Laboratories) assays. Patients were divided into TgAb- and TgAb+ based on the limit of detection (LoD; ≥0.07 IU/mL), functional sensitivity (FS; ≥0.31 IU/mL), MCO (≥4.11 IU/mL), and ICO (≥10 IU/mL).

RESULTS

All patients were TgAb+ based on the LoD; one patient was negative on FS. Fifty-five (23.9%) and 34 (14.8%) patients had TgAbs above the MCO and ICO, respectively. Histology, presence of multifocality, tumor-node-metastasis, and American Thyroid Assocation risk stratification did not differ between TgAb- and TgAb+ patients using MCO and ICO during ablation.

CONCLUSIONS

This study supports the use of a higher cutoff value than that of the FS for TgAb positivity in clinical settings. The LoD and FS are too sensitive to discriminate TgAb positivity and negativity in DTC patients during ablation therapy. The presence of TgAbs during ablation is not related to tumor characteristics and risk profile. This implies that TgAb positivity should not be considered a separate risk factor.

Clinical implications of anti-thyroglobulin antibody measurement before surgery in thyroid cancer

Thyroglobulin antibody (TgAb) is a class G immunoglobulin and a conventional marker for thyroid autoimmunity. From a clinical perspective, TgAb is less useful than thyroid peroxidase antibodies for predicting thyroid dysfunction. However, TgAb is found more frequently in differentiated thyroid cancer (DTC) and can interfere with thyroglobulin (Tg) measurements, which are used to monitor the recurrence or persistence of DTC. Recent studies suggested a small but consistent role for preoperative TgAb in predicting DTC in thyroid nodules, and in reflecting adverse tumor characteristics or prognosis, including lymph node metastasis, but this is still controversial. Postoperative TgAb can serve as a biomarker for remnant thyroid tissue, so follow-up measures of TgAb are useful for predicting cancer recurrence in DTC patients. Since high serum TgAb levels may also affect the fine needle aspiration washout Tg levels from suspicious lymph nodes of DTC patients, it is important to use caution when interpreting the washout Tg levels in patients who are positive for TgAb.

Harmonization in autoimmune thyroid disease diagnostics

In this review we analyze all aspects of total testing process regarding the measurement of antithyroid peroxidase, antithyroglobulin and antithyrotropin receptor autoantibodies. The main critical points related to the preanalytical, analytical and postanalytical steps of autoimmune thyroid disease diagnostics are considered, focusing on harmonization of autoimmune thyroid tests request, retesting intervals, terminology of thyroid autoantibodies, measurement units and definition of reference limits. Harmonization in thyroid autoantibody testing is a relevant example of feasible harmonization in autoimmunology.