Serum thyroglobulin in thyroid cancer

Plasma cell-free DNA as predictor of disease status in patients with differentiated thyroid cancer - a prospective study from a tertiary care institution

Introduction

Plasma cell-free DNA (cfDNA) estimation offers a non-invasive method to potentially diagnose, monitor, and prognosticate patients with malignancy. This prospective study aimed to assess plasma cfDNA levels in patients with differentiated thyroid cancer (DTC) to determine its role in predicting disease status in the post-operative setting.

Materials and methods

This was a single-center prospective observational study conducted at a public medical research university and hospital in New Delhi, India. 254 patients with DTC in the post-operative setting were included: 95 in Group 1 (active structural disease) and 159 in Group 2 (disease-free). Blood samples were collected for plasma separation and cfDNA extraction. The cfDNA concentrations were quantified and compared across various disease states.

Results

Median values of plasma cfDNA (ng/µL) in groups 1 and 2 were found to be 0.272 (IQR: 0.137-0.442) and 0.222 (IQR: 0.123-0.398), respectively with no significant difference (p=0.122). cfDNA levels were significantly higher in patients in the age group ≥55 years (p=0.016). However, the cfDNA levels were not significantly associated with any of the other known prognostic markers of DTC.

Discussion

Based on the results of this study, plasma cfDNA levels did not significantly predict disease status in patients with DTC in the post-operative setting.

The role of a new polyclonal competitive thyroglobulin assay in the follow-up of patients with differentiated thyroid cancer with structural disease but low levels of serum thyroglobulin by immunometric and LC-MS/MS methods

PURPOSE

The aims of this study were to assess the role of an in-house competitive thyroglobulin assay (Tg-c) in the follow-up of metastatic differentiated thyroid carcinoma (DTC) patients who presented underestimated Tg measurements by immunometric assays (Tg-IMA) and to compare the results with IMA and LC-MS/MS Tg methods.

METHODS

This prospective study included 40 patients. Twenty-one with metastatic disease: 14 had Tg-IMA levels inappropriately low or undetectable (eight patients with positive and six with borderline TgAb) and seven had high Tg-IMA levels. Nineteen had an excellent response to therapy. The competitive assay employs a polyclonal antibody produced in rabbits immunized with human Tg, Tg labeled with biotin, and for the solid phase separation, a monoclonal anti-rabbit IgG antibody adsorbed to microtiter plates.

RESULTS

All 14 patients with structural disease and underestimated levels of Tg-IMA presented detectable Tg-c levels. The median Tg-c level in the group with positive TgAb was 183 µg/L (range: 22-710 µg/L), and 58 µg/L (range 23-148 µg/L) in the borderline TgAb group. The levels of Tg-LC-MS/MS were detectable in some patients (range < 0.5-18 µg/L). All seven patients with high Tg-IMA presented also high levels of Tg-c. Only 2/19 patients with excellent response had Tg-c levels above the functional sensitivity.

CONCLUSIONS

The competitive assay was able to detect Tg in all patients, even in the presence of serum TgAb, and may be an option in patients with underestimated Tg-IMA and relevant structural disease.

Value of post-therapeutic ¹³¹I scintigraphy in stimulated serum thyroglobulin-negative patients with metastatic differentiated thyroid carcinoma

Metastatic differentiated thyroid carcinoma (DTC) with positive (131)I scintigraphy, but negative stimulated Tg (sTg) is relatively rare in clinical practice. The clinical characteristics of these patients were analyzed in the current study. A total of 3367 consecutive histologically proven DTC patients were analyzed retrospectively from January 2007 to June 2013. Tg negativity was defined as a sTg level of <2 ng/mL without positive anti-Tg antibody (TgAb level of <100 IU/mL) under thyroid-stimulating hormone stimulation (TSH level of ≥30 mIU/L). Analyses were performed using the Statistical Package for the Social Sciences, version 20.0 (SPSS, Chicago, IL, USA). Seventy-one patients (median age 45 years, range 17-68 years) were post-therapeutic (131)I-SPECT/CT positive and sTg negative (PTP-TN) constituting 2.1 % of all patients. Of these 71 patients, 2 (2.8 %) had bone metastasis, 11 (15.5 %) had lung metastasis, and 59 (83.1 %) had lymph node metastasis. Fifty-six patients had cervical lymph node metastasis (cLNM), and US was positive in 15 patients (26.8 %), while negative in 41 patients (73.2 %). When compared to patients with concordant positive results for sTg and (131)I scintigraphy, US showed a relatively lower positive rate in the detection of cLNM in PTP-TN patients (28.8 vs. 53.8 %; χ (2) = 6.70; P = 0.01). In conclusion, even with sTg <2 ng/mL, there is a low risk of metastatic DTC. US had limitations in PTP-TN patients, while post-therapy (131)I-SPECT/CT demonstrated an advantage in the detection of functioning metastasis despite low sTg levels in patients with metastatic DTC.

Value of 18F-FDG PET negativity and Tg suppressibility as markers of prognosis in patients with elevated Tg and 131I-negative differentiated thyroid carcinoma (TENIS syndrome)

AIMS

The aim of the study was to investigate the prognostic value of fluorine-18 fluorodeoxyglucose (18F-FDG) PET negativity and thyroglobulin (Tg) suppressibility in differentiated thyroid carcinoma patients with elevated Tg and a negative radioiodine scan.

MATERIALS AND METHODS

The study population was selected from thyroid cancer patients registered at a large tertiary cancer care center for management and consisted of patients with metastatic thyroid cancer with elevated Tg on follow-up, negative 131I whole-body scan and negative 18F-FDG PET/computed tomography (CT) study. Patients with thyroid carcinoma were subjected to a thyroid-stimulating hormone-stimulated assessment on the basis of a 131I whole-body scan, serum Tg level and whole-body 18F-FDG PET/CT scan for evaluation of metastatic disease burden. The same patients were subjected to a follow-up evaluation of serum Tg and whole-body 18F-FDG PET/CT scan under thyroid-stimulating hormone suppression while on thyroxine sodium. Comparison was also made between the findings of 18F-FDG PET/CT in patients demonstrating suppressible Tg.

RESULTS

A total of 40 (25 male and 15 female) patients were included in the study. All patients had a negative whole-body 18F-FDG PET/CT study but had stimulated Tg more than 5 ng/dl (range: 5.1-> 250 ng/ml), indicating the presence of disease. The patients demonstrated variable Tg suppressibility and were classified on the basis of the extent of Tg suppressibility (%Tg suppressibility > 90% in 21 patients; %Tg suppressibility 65-90% in 12 patients; and %Tg suppressibility < 65% in five patients; and no suppressibility in two patients). 18F-FDG PET was normal in all of these patients both on stimulation and on suppression. All patients were asymptomatic during this period. No definite correlation could be established between the status of metastasis or the histopathology and suppressibility of Tg. The average follow-up data available were for more than 3 years in 26 patients (two patients had no Tg suppressibility in this group), for 1-3 years in 10 patients and for less than 1 year in four patients. At the time of analysis in this study the patients were asymptomatic during the aforementioned follow-up periods (based upon follow-up data available).

CONCLUSION

In this study, we observed that 'elevated Tg but normal 18F-FDG PET' exists as a definitive entity in differentiated thyroid carcinoma. On the basis of the studied follow-up, a negative 18F-FDG PET in the setting of elevated Tg level could be regarded as a favorable prognostic indicator to predict symptom-free status during the follow-up period in this group of patients. Suppressibility of Tg (> 65%) is observed in a significant fraction of these patients, which appears to be independent of the status of metastasis or the histopathology. Also patients who show no Tg suppressibility but had a negative 18F-FDG PET/CT scan still had a better prognosis indicated by the disease-free interval in these patients as indicated in our study. Whether there exists any relation between the extent of suppressibility and their long-term outcome requires to be further examined in future prospective studies.

Diagnostic Value of Preoperative Serum Thyroglobulin Measurement for the Diagnosis of Malignancy in Follicular or Hürthle Cell Neoplasms of the Thyroid Gland

<title>Abstract</title><sec><title>Objectives</title><p>The aim of this retrospective study was whether serum Tg predicts malignancy in follicular or Hürthle-cell neoplasms on fine needle aspiration.</sec><sec><title>Methods</title><p>A chart review of 111 patients (90 females, 21 males; mean age 46.8 ± 11.9 years) with follicular or Hürthle-cell neoplasms on fine needle aspiration, who were surgically treated between Sep. 2001 and Sep. 2011, was performed. Predictive factors for malignancy were identified by the chi-squared test and multivariate logistic regression.</sec><sec><title>Results</title><p>There were no differences between 41 malignant and 70 benign lesions in serum Tg or any of the normalized indexes. Receiver-operator characteristic analysis revealed no cutoff value. Lesions with serum Tg levels greater than 500 g/L had no significant difference. And also there were no independent predictors of malignancy by multivariate logistic regression.</sec><sec><title>Conclusions</title><p>In this study, the author found that serum Tg has poor accuracy for predicting malignancy in follicular or Hürthle cell neoplasms on fine needle aspiration.</sec>

Discordance in thyroglobulin measurements by radioimmunoassay and immunometric assay: a useful means of identifying thyroglobulin assay interference

Background

Serum thyroglobulin (Tg) is useful for monitoring patients with differentiated thyroid cancer (DTC) but is limited by interference from anti-Tg antibodies (TgAb). We determined Tg assay discordance between a radioimmunoassay (RIA) and one of two immunometric assays (IMA) in DTC patients over a 9-year period to gauge assay performance against evidence of recurrent/progressive DTC.

Methods

Patients with DTC monitored for >1 year attending local clinics between September 2000 and January 2010 were included. All samples were analysed for Tg using both RIA and IMA. TgAb were measured on all Tg requests made after May 2006. Bias plots comparing RIA against IMA were established to calculate a 2-SD outlier limit. Clinical records were viewed to compare discordant Tg results against clinical evidence of recurrent/progressive DTC.

Results

Discordant Tg results were observed in 53/433 patients (12.2%). Four were discordant owing to a higher IMA result, one of which demonstrated recurrence. The remaining 49 patients demonstrated a disproportionately higher RIA result, of which four had recurrent/persistent disease. Twelve patients with a higher RIA result but no evidence of recurrence underwent thyrogen stimulation testing, which was negative in all 12. In many cases, assay discordance appeared more sensitive at indicating interference than direct measurement of TgAb.

Conclusions

Interference was evident with both Tg assays, such that neither could be solely relied upon to provide the correct result in the presence of TgAb. The concomitant measurement of Tg by RIA and IMA methods should be considered as an alternative to monitoring TgAb status.

Application of post-surgical stimulated thyroglobulin for radioiodine remnant ablation selection in low-risk papillary thyroid carcinoma

BACKGROUND

We present our ongoing experience in the use of postsurgical stimulated serum thyroglobulin (Stim-Tg) to assist in radioiodine remnant ablation (RRA) decision-making.

METHODS

Patients with low-risk well-differentiated thyroid carcinoma (WDTC) with undetectable anti-Tg antibodies were prospectively followed after total thyroidectomy and therapeutic central compartment neck dissection, when indicated.Stim-Tg was performed 3 months postoperatively and used to base RRA selection.

RESULTS

Of 104 patients, 59 patients (56.7%) had an undetectable Stim-Tg after thyroidectomy, 35 (33.7%) had Stim-Tg values of 1-5 microg/L, and 10 (9.6%) had Stim-Tg values >5 microg/L. RRA was administered to 1 patient (1.7%) with undetectable Stim-Tg, 6 patients (17.1%) with Stim-Tg1-5 microg/L, and 9 patients (90%) with Stim-Tg >5 microg/L, for a total of 16 patients (15.4%) receiving RRA. When compared to current RRA selection guidelines, the proposed protocol achieved a significantly lower RRA administration rate.

CONCLUSION

Stim-Tg measurement performed several months after total thyroidectomy is a useful objective parameter in assisting RRA decision-making for patients with low-risk WDTC. (

Clinical importance of anti-thyroglobulin auto-antibodies in patients with differentiated thyroid carcinoma: Comparison with 99mTc-MIBI scans

AIMS

(1) To investigate whether elevated serum anti-thyroglobulin antibody (ATG) reflects the recurrence of cancer in patients with differentiated thyroid carcinoma (DTC) in whom thyroglobulin was undetectable after radioiodine ablation. (2) To assess the sensitivity of disease detection for (99m)Tc-MIBI whole-body scans (WBSs) in these patients and investigate the correlation between MIBI WBS results and high serum ATG levels.

MATERIALS AND METHODS

In this retrospective study, we evaluated 14 patients (13 women and 1 man; mean age 44 +/- 19 years) with DTC who underwent total or near-total thyroidectomy followed by an ablative dose of I at various time intervals. According to histopathological findings, 10 patients (71.4%) who were diagnosed as having papillary carcinoma and four patients (28.6%) as having follicular cell carcinoma, had high serum ATG concentrations (> 40 IU x ml(-1); range, 62-2000 IU x ml(-1)), but low serum thyroglobulin concentrations (< 1.6 ng x ml). Post-therapeutic and diagnostic (131)I WBSs and (99m)Tc-MIBI WBSs were performed. Scans were visually evaluated for detecting recurrence. If necessary, bone scans, chest X-rays, computerized tomography, ultrasonography and histopathological evaluation were performed.

RESULTS

Recurrent and/or persistent disease was found in 12 of the patients. This was confirmed pathologically in four patients and by using other imaging methods in eight (bone scans, computerized tomography, ultrasonography). The sensitivity and specificity of disease detection for MIBI WBSs was 66.7% and 100%, respectively. For (131)I WBSs, the sensitivity of disease detection was 55.6%. Among these 12 patients, 10 responded to treatment (three underwent surgery, seven received radioiodine therapy, and two had surgery + radioiodine therapy). ATG levels decreased in eight of the 10 patients, but remained persistently elevated in two despite treatment.

CONCLUSIONS

(1) Persistently elevated ATG levels appear to serve as a useful marker for recurrent or persistent DTC in patients with undetectable serum tyroglobulin levels. Thus, the routine measurement of ATG antibody in such patients is of great value. (2) In these patients, (99m)Tc-MIBI has a relatively high sensitivity in the diagnosis of a recurrence of thyroid cancer or metastases. So, in patients with elevated ATG but undetectable serum thyroglobulin levels, (99m)Tc-MIBI can be used to determine whether there is a recurrence of DTC or metastases.

Differentiated thyroid carcinoma with distant metastases at presentation: prognostic factors and outcome

BACKGROUND

Differentiated thyroid cancer (DTC) presenting with distant metastases is uncommon. Prognostic factors that affect survival remain unclear.

AIM

To evaluate factors influencing the survival of patients with DTC presenting with distant metastases.

METHOD

A retrospective study of 111 patients (62 F, 49 M) with DTC who presented with distant metastases (M1) treated at the Royal Marsden Hospital from 1940 to 2002.

RESULTS

The median follow-up of living patients was 3.9 years (0.3-48) with a 10-year cause-specific survival rate of 31%. Histology identified 46 papillary, 60 follicular and five Hürthle cell cancers. Sites of metastases comprised 54 lung (49%), 27 bone (24%), 21 multiple sites (19%) and nine with other single sites affected (8%). Near-total, total or completion thyroidectomy was performed in 56% of patients, radioiodine ablation in 76% and radioiodine therapy in 67%. External beam radiotherapy was given to 12 patients and the same number received chemotherapy. Univariate analysis was performed with cause-specific survival as the main outcome measure. Age over 70, poorly differentiated tumours and Hürthle cell cancers were associated with worse outcomes (P < 0.01). Patients with multiple organ metastases had a worse survival (P = 0.02). Radical surgery did not significantly improve outcome compared to more conservative forms of surgery (subtotal thyroidectomy, hemi-thyroidectomy or lobectomy) but patients receiving radioiodine ablation and therapy had improved survival (P < 0.01). Multivariate analysis identified age over 70, poorly differentiated tumours and Hürthle cell variant to be the only independent factors associated with worse outcome (P < 0.01). Treatment in the 1991-2002 era was associated with an improved survival compared to all previous decades (P = 0.009).

CONCLUSIONS

Patients with DTC presenting with distant metastases have a worse outcome if aged over 70, have poorly differentiated tumours or have Hürthle cell variant. Despite their unfavourable prognosis, a dramatic improvement in survival was observed in the most recent era (1991-2002).

Gasless Video-assisted Total Thyroidectomy in the Treatment of Low Risk Intrathyroid Papillary Carcinoma

Video-assisted thyroidectomy, although an increasingly used method to treat benign thyroid nodules, is rarely used to treat thyroid cancer. We performed gasless video-assisted total thyroidectomy for the treatment of papillary carcinoma of the thyroid. The patients were two men and five women with ages ranging from 29 to 52 years (median 35 years). Tumor size ranged from 0.7 to 3.8 cm (median 1.8 cm). The remnants of functional thyroid tissues were ablated with 1110 MBq of 131I following total thyroidectomy. One year after radioiodine ablation uptake of 74 MBq 131I shown by scintigraphy ranged from 0.29% to 0.70% (median 0.57%), and the serum thyroglobulin level was less than 1 microg/L. No perioperative complications occurred. The follow-up period ranged from 1 year 5 months to 3 years 7 months (median 2 years 10 months). In conclusion, gasless video-assisted total thyroidectomy is a feasible means for treating relatively small, non-invasive, clinically solitary, differentiated thyroid carcinomas.

PET in the follow-up of differentiated thyroid cancer

Fluorine-18-fluorodeoxyglucose (FDG) PET has become an increasingly important functional imaging modality in clinical oncology. This article will focus primarily on the role of FDG PET during treatment and follow-up of thyroid cancer. The major role of FDG PET is in patients with elevated thyroglobulin (Tg) levels where thyroid cancer tissue does not concentrate radioiodine rendering false-negative results on I-131 scanning. FDG PET imaging takes advantage of the increased uptake of FDG in cancer cells and is sensitive (60-94%) to the detection of recurrent or metastatic cancer in patients who have negative radioiodine scans. The specificity (25-90%) of PET imaging is relatively less than its sensitivity because some inflammatory processes avidly accumulate FDG. PET can fail to localize the tumour sites in some patients with well-differentiated thyroid cancer that retain good iodine ability. This can result the well recognized phenomenon of "flip-flop" depending on the differentiation of the thyroid cancer. Several studies have documented the higher accuracy of PET, compared with other imaging modalities in the evaluation of patients with recurrent or metastatic differentiated thyroid cancer. The value of thyroid stimulating hormone stimulation for FDG PET has recently been reported. Therefore, if available, this method should be considered in all patients of differentiated thyroid cancer with suspected recurrence and/or metastasis.

Serum thyroglobulin measurements with a high sensitivity enzyme-linked immunosorbent assay: is there a clinical benefit in patients with differentiated thyroid carcinoma?

Serial serum thyroglobulin (Tg) measurements with a highly sensitive enzyme-linked immunosorbent assay (ELISA; functional sensitivity 0.03 ng/mL) in 126 patients (Tg autoantibody negative) with treated differentiated thyroid cancer (DTC) are described. At the beginning of the retrospective study, all 126 patients were in remission and Tg was detectable by ELISA in 92 (73%; range, 0.03-0.8 ng/mL). Over the following 4-year period, Tg levels remained essentially unchanged (i.e., any increases were less than 2 times the Tg level at the start of the study) in 121 of 126 (96%) and all 121 patients remained well. In 5 patients, Tg levels increased to more than 2 times the starting Tg level over the study period and in 4 of these 5, there was recurrence of DTC. The fifth patient in this group remains well as evidenced by extensive diagnostic imaging, although his serum Tg level continues to increase and can be stimulated by thyrotropin (TSH). Our results suggest that serial measurements of low levels of Tg by ELISA in treated patients with DTC enable detection of recurrence (without using TSH stimulation) 6-12 months earlier than would have been possible using a conventional Tg immuno-radiometric assay (IRMA). A prospective study is now needed to confirm these observations.

Discordant serum thyroglobulin results generated by two classes of assay in patients with thyroid carcinoma: correlation with clinical outcome after 3 years of follow-up

BACKGROUND

Serum thyroglobulin measurement is an integral part of monitoring patients with thyroid carcinoma, but analytic problems pose serious difficulties in the utility of this test.

METHODS

Between 1997 and 1998, serum samples from 83 patients with differentiated thyroid carcinoma were collected. Serum thyroglobulin was assayed by both radioimmunoassay and by an immunoradiometric assay. The disease status of patients with discordant serum thyroglobulin results was assessed in June 2001. Therefore, the predictive value of a single thyroglobulin measurement was assessed by evaluating the clinical status of patients 3 years later.

RESULTS

Discordant serum thyroglobulin results were noted in 17 (20.4%) patients. Of the 17 patients with discordant results, 16 had adequate clinical follow-up data. Of these 16 patients, 11 patients had detectable levels of serum thyroglobulin by immunoradiometric assay (range, 1.4-350 microg/L) whereas levels were undetectable by radioimmunoassay (< 1 microg/L). All 11 patients had evidence of metastases 3 years later. Two patients had undetectable serum thyroglobulin levels using the immunoradiometric assay (< 1 microg/L), whereas they had detectable levels using radioimmunoassay (serum thyroglobulin 7.2-30 microg/L). The serum samples from both patients had normal recoveries and positive antithyroglobulin antibodies. Both patients developed metastases 3 years later.

CONCLUSIONS

False-negative serum thyroglobulin results were significantly higher with the radioimmunoassay method compared with the immunoradiometric assay. The immunoradiometric assay is more reliable than the radioimmunoassay, particularly in patients who have no thyroglobulin antibodies. This finding is novel in that traditional immunoradiometric assay systems compared with radioimmunoassays usually have a higher incidence of false-negative results when assessed against clinical status. The immunoradiometric assay is subject to false-negative results in some patients with thyroglobulin antibodies, even when recovery experiments indicate the absence of interference. Thyroglobulin antibodies should be measured in all patients with differentiated thyroid carcinoma and if positive, results should be interpreted with extreme caution.

Measurement of thyroglobulin mRNA in peripheral blood as an adjunctive test for monitoring thyroid cancer

AIMS

Monitoring treated patients with thyroid cancer for recurrent or metastatic disease is currently based upon the serial measurement of circulating plasma thyroglobulin (Tg) concentrations. However, the clinical usefulness of Tg immunoassays is limited by poor sensitivity and interference from anti-Tg antibodies. This study investigated whether the detection of Tg mRNA in peripheral blood, using reverse transcriptase polymerase chain reaction (RT-PCR), is of value in the biochemical surveillance of patients with thyroid cancer.

METHODS

RNA was extracted from peripheral blood of five normal controls, six patients with abnormal thyroid function tests, and 28 patients who had undergone thyroidectomy for well differentiated thyroid cancer. From each, an 87 bp product from base pair 262 to 348 in the cDNA sequence of the thyroglobulin gene was amplified by RT-PCR.

RESULTS

Tg mRNA was detected in normal individuals and patients with thyroid cancer. In the group of patients studied, identification of metastatic thyroid tissue by radioiodine scanning correlated better with Tg mRNA assay results than with serum Tg concentrations (accuracy 84% v 75%). No interference from circulating Tg antibodies was apparent. In patients studied prospectively over a 12 month period, there was a significant correlation between detectable Tg mRNA in peripheral blood and the presence or absence of metastatic disease, as demonstrated by radioiodine scanning.

CONCLUSIONS

These results suggest that detection of Tg mRNA in blood is a more sensitive marker for metastatic thyroid disease than Tg immunoassay, and appears to be unaffected by the presence of circulating anti-Tg antibodies.

Predictive value of serum thyroglobulin after surgery for thyroid carcinoma

OBJECTIVE

To determine the relationship between stimulated serum thyroglobulin levels (taken 3 months after total thyroidectomy) and tumor stage and recurrence in patients with well-differentiated thyroid carcinoma.

STUDY DESIGN

Retrospective chart review in a tertiary care institution.

METHODS

Two hundred thirteen consecutive patients with well differentiated thyroid carcinoma treated between 1983 and 1998 were identified. Data were collected on clinicopathological variables, stimulated serum thyroglobulin levels obtained 3 months after total thyroidectomy prior to 131I therapy and recurrence.

RESULTS

A high postoperative thyroglobulin level was significantly associated with advanced-stage disease at presentation (P =.005, Kruskall-Wallis) but not with any of the other clinicopathological variables. Patients with a thyroglobulin level greater than 20 pmol/L had a significantly increased risk of disease recurrence on univariate analysis (n = 213 [P =.0001, log rank test]), and in the Cox proportional-hazards model, both advanced tumor stage (P =.001, relative hazard, 3.4 [95% confidence interval [CI]: 2.4-4.9]) and a thyroglobulin level greater than 20 pmol/L (P =.001, relative hazard, 5.1 [95% CI: 2.0-13.1]) were significant predictors of recurrence. No other variables significantly altered the hazards model.

CONCLUSIONS

Advanced tumor stage at diagnosis and a stimulated thyroglobulin level greater than 20 pmol/L taken 3 months after total thyroidectomy were independent predictors of disease recurrence. Patients with a thyroglobulin level greater than 20 pmol/L are at increased risk of recurrence and may be candidates for more intensive follow-up or additional treatment.

Clinical significance of elevated level of serum antithyroglobulin antibody in patients with differentiated thyroid cancer after thyroid ablation

OBJECTIVE

This study was designed to investigate whether an elevated serum antithyroglobulin antibody (TgAb) reflects cancer recurrence in thyroglobulin (Tg)-undetectable patients with differentiated thyroid carcinoma (DTC) after thyroid ablation.

DESIGN

We measured serum TgAb level and evaluated the disease status in 226 DTC patients who had undergone remnant ablation and showed an undetectable Tg result as assessed by immunoradiometric assay.

MEASUREMENTS

Radioligand assay of TgAb was performed. Recurrence was assessed by 131I scan, 18F-fluorodeoxyglucose positron emission tomography, sonography, computed tomography, or by surgical operation.

RESULTS

Fifty-one patients (22.6%) of the Tg-undetectable patients showed positive TgAb, and 25 (49.0%) of these were confirmed with recurrence. The recurrence rate of TgAb-positive patients was higher than that of TgAb-negative patients (3.4%; P < 0.0001). During follow-up, 73.1% of the disease-free patients showed spontaneously decreased TgAb levels. A total of 71.4% of patients with recurrent cancer, who showed responses to surgical operation or radio-iodine treatment, also showed a decreased TgAb level.

CONCLUSIONS

Persistently elevated TgAb levels appear to serve as a useful marker for recurrent or persistent DTC in patients with undetectable serum Tg results. Thus, the routine measurement of TgAb in such patient populations may be indicated.

A high-sensitivity enzyme-linked immunosorbent assay for serum thyroglobulin

A sensitive enzyme-linked immunosorbent assay (ELISA) for measuring serum thyroglobulin (Tg) is described. The assay has a functional sensitivity of 0.03 ng/mL and values obtained in sera from patients with treated differentiated thyroid cancer (DTC; n = 24, 17 of whom showed some evidence of recurrence) and from healthy blood donors (n = 48) were in agreement with those obtained by Tg immunoradiometric assay (IRMA) (functional sensitivity = 0.6 ng/ml) (r = 0.99 and 0.98 for the two groups, respectively). The Tg levels measured by ELISA in 47 of the healthy blood donor sera ranged from 2.3 to 139 ng/ml with 1 serum giving a value of 0.03 ng/mL. The mean +/- standard deviation (SD) Tg concentration for the healthy blood donors was 20.3+/-23 ng/mL. Studies with a recovery test suggest that Tg measurements by ELISA were not always reliable when Tg autoantibodies were present. Analysis of samples from 167 patients treated successfully for DTC (papillary carcinoma, 94; follicular carcinoma, 73) showed that 139 were negative for Tg autoantibodies and of these 106 (76%) had Tg levels measurable by ELISA (0.03 ng/mL or greater). In contrast, only 7 (5%) of these 139 sera had Tg levels measurable by IRMA (0.6 ng/mL or greater). It is possible that this ability to measure Tg simply and easily in most treated DTC patients will have significant advantages for patient care. In particular, the Tg level after initial ablative treatment will usually be measurable rather than undetectable. Furthermore, any increases in serum Tg levels which may herald relapse will be detectable earlier.

An audit of management of differentiated thyroid cancer in specialist and non-specialist clinic settings

OBJECTIVE

Thyroid cancer is the most common endocrine malignancy but is none the less rare. Some aspects of its management remain controversial. Previous audits of patient management in the United Kingdom have revealed deficiencies, especially in communication between specialists. We have audited patient management in a large university-associated teaching hospital, assessing points of good practice identified from published guidelines and reviews, and have compared findings in groups of patients managed jointly by specialists with an interest in thyroid cancer (including surgeon, endocrinologist and oncologist) with a group managed by other clinicians outside that setting.

DESIGN AND PATIENTS

Retrospective case-note review of 205 patients with differentiated (papillary or follicular) cancer including group A (n = 134; managed in a specialist multi-disciplinary clinic setting) and group B (n = 71; managed in other clinic settings). Points of good practice investigated were adequacy of surgery, surgical complications, prescription and adequacy of T4 treatment, adequacy of monitoring by measurement of serum thyroglobulin and action taken and appropriate administration of ablative radioiodine.

RESULTS

Deficiencies in management of the cohort as a whole were identified, including inadequate surgery and inadequate TSH suppression in approximately one-fifth of the cases. Monitoring with thyroglobulin measurements and action when serum thyroglobulin was high were also inadequate in some cases and ablative radioiodine was not given, despite being indicated in 11.7% of the cohort. Inadequate surgery and failure to administer radioiodine were less common in those managed in a specialist clinic setting than in those managed in other clinic settings.

CONCLUSIONS

The findings highlight the need for locally agreed protocols in managing relatively rare endocrine disorders such as thyroid cancer and argue in favour of centralization of expertise and patient management in multi-disciplinary specialist clinic settings.

Serum thyroglobulin measurement. Utility in clinical practice

Serum thyroglobulin measurement has greatly facilitated the clinical management of patients with differentiated thyroid cancer and a variety of other thyroid disorders. Thyroglobulin autoantibodies remain a significant obstacle to the clinical use of thyroglobulin measurement. The interpretation of any given thyroglobulin value requires the careful synthesis of all pertinent clinical and laboratory data available to the clinician. The diagnostic use of rhTSH-stimulated thyroglobulin levels has greatly facilitated the follow-up of low-risk patients with thyroid cancer. Although the measurement of thyroglobulin mRNA from peripheral blood is likely to affect the future management of these patients, it is expected that serum thyroglobulin measurement will continue to have a principal role in the care of patients with differentiated thyroid cancer.

Value of protein-bound radioactive iodine measurements in the management of differentiated thyroid cancer treated with (131)I

Measurement of the protein-bound radioactive iodine level (PBI(131)) in the plasma of patients following (131)I-iodide administration for thyroid cancer has been re-examined in a retrospective study of 171 patient episodes. It is shown that whereas the previously used threshold value for the measurement at 6 days does not correlate well with the 3-day whole body scan, there is good agreement between the scan and the temporal changes in PBI(131) from 1-6 days: an increasing PBI(131) correlates with a positive scan, and a decreasing PBI(131) with a negative scan. The area under the curve (AUC) for the PBI(131)-time curve is related to the absorbed dose for the tumour. For a small group of 11 patients, dosimetry estimates were made from serial scans, quantified with phantoms; these absorbed doses correlated with the AUC and the 6-day PBI(131). Therefore, it is suggested that these parameters may be useful in predicting absorbed radiation dose in these patients.

The thyroid and parathyroid glands. CT and MR imaging and correlation with pathology and clinical findings

Thyroid imaging approach is based on the preliminary clinical evaluation. Lesions that are smaller than 2 cm should be assessed with US, which is capable of discriminating masses as small as 2 mm and distinguishing solid from cystic nodules. US-guided FNAB provides tissue for cytologic examination of thyroid nodules. CT and MR imaging are indicated for larger tumors (greater than 3 cm diameter) that extend outside the gland to adjoining structures, including the mediastinum, and retropharyngeal region. Metastatic lymph nodes in the neck and invasion of the aerodigestive tract are also in the realm of CT and MR imaging. Thyroid nodules are categorized on scintigraphy as hot or cold nodules. Hot nodules are rarely malignant, whereas cold nodules have an incidence of 10% to 20% of malignancy. Calcifications (amorphous, globular, nodular, and linear) occur in adenomas and carcinomas and have no differential diagnostic features except for psammomatous calcifications, which are a pathognomonic finding in papillary carcinomas and a small percentage of medullary carcinomas. Papillary carcinoma is the most common malignant tumor (80%) followed by follicular (20% to 25%); medullary (5%); undifferentiated; anaplastic carcinomas (< 5%); lymphoma (5%); and metastases. Lymph node metastases are common in papillary carcinoma, 50% at presentation, and less common in follicular carcinomas. The metastatic nodes in papillary carcinoma may enhance markedly (hypervascular); show increased signal intensity on T1-weighted images (increased thyroglobulin content or hemorrhage); and reveal punctate calcifications. Localized invasion of the larynx, trachea, and esophagus occurs predominantly in papillary and follicular carcinomas; the incidence is less than 5%. Ectopic thyroid tissue may be encountered in the tongue (foramen cecum); along the midline between posterior tongue and isthmus of thyroid gland; lateral neck; mediastinum; and oral cavity. Goiter and malignant tumors, notably papillary carcinoma, may develop in ectopic thyroid tissue. Carcinomas may also arise in thyroglossal duct cysts, which develop from duct remnants between the foramen cecum and thyroid isthmus. Infectious disease of the thyroid gland is not common and the CT and MR imaging findings are similar as described under neck infection. Other types of inflammatory disorders including Hashimoto's thyroiditis, granulomatous thyroiditis, and Riedel's struma display no specific imaging features. Imaging studies may, however, be indicated to confirm a suspected clinical diagnosis and assess compromise of the airway (Riedel's struma). HPT is a clinical diagnosis in which hypercalcemia is the most important finding. Parathyroid hyperplasia, adenoma, and carcinoma represent underlying lesions. To relieve the patient's symptoms surgical extirpation is indicated. The surgical success rate without imaging is 95%. The indications for imaging studies vary but it is generally agreed that reoperation after a previous failed surgical attempt and suspicion of an ectopic parathyroid adenoma should be investigated by imaging. These consist of US, nuclear medicine studies, CT and MR imaging. US and technetium sestamibi scanning have the highest accuracy rate for localizing an adenomatous gland at and near the thyroid gland. Ectopic adenomas, particularly if they are located in the mediastinum, are preferrably investigated with CT and MR imaging with gadolinium and fat suppression. Carcinomas and parathyroid cysts are optimally evaluated by CT and MR imaging. On MR imaging adenomas are low in signal intensity on T1-weighted images, high in signal intensity on T2-weighted images, and enhance post introduction of gadolinium.

False positive 131I whole body scans in thyroid cancer

Well differentiated thyroid cancer is a rare disease in the UK. It is the only cancer which, having metastasized, remains curable by radioisotope therapy with 131I. The main indication for administering repeat doses of 131I is the appearance of abnormal uptake in a whole body scan following diagnostic or therapeutic 131I administration. False positive scans, showing the presence of 131I uptake in the absence of residual thyroid tissue or metastases can occur, although they are uncommon. Unless recognized as a false positive, 131I uptake may result in diagnostic error and lead to administration of an unnecessary therapy dose. We describe a series of nine patients in whom the scans showed false positive uptake of 131I, including cases where the cause of the uptake is still uncertain. We demonstrate the common sites of false positive uptake, discuss the underlying mechanisms and suggest a systematic approach to the interpretation of whole body scans in order to prevent unnecessary treatment with 131I.

Thyroid cancer in children: the Royal Marsden Hospital experience

The first child with well-differentiated thyroid cancer treated at the Royal Marsden Hospital presented in 1917. Since that time 30 children under the age of 16 years have been treated over a period during which many new treatments have been introduced. We have reviewed their management and outcome. The median follow-up is 22.5 years (range: 1-66). The median time to recurrence was 7 years (range: 2-44). There were events up to 44 years after presentation. The risk of recurrence was higher in children aged 10 years or younger [HR 3.45, 95% CI (1.04-11.11) P = 0.03]. Thyroid stimulating hormone (TSH) suppression was the only intervention to be shown to reduce the recurrence rate [HR 11, 95% CI (2.27-50) P = 0.0003]. The median overall survival is 53 years. The only presenting feature predictive of poorer survival was the presence of metastases (HR 28.96, 95% CI 2.51-334, P < 0.001). Patients who developed recurrence had a higher risk of death (HR 9.90, 95% CI 0.98-100, P = 0.02) and a shorter median survival of 30 years. No therapeutic intervention could be shown statistically to impact on survival. Our recommendation for treatment is total or near-total thyroidectomy for all patients and radioiodine ablation for all except those with early T stage node-negative disease aged over 10 years. Modified neck dissection is recommended for children with clinically positive neck nodes and TSH suppression for all. Follow-up with serial thyroglobulin measurement should be lifelong.

Value of stimulated serum thyroglobulin levels for detecting persistent or recurrent differentiated thyroid cancer in high- and low-risk patients

BACKGROUND

Serum thyroglobulin determination has been reported to be a sensitive indicator of persistent or recurrent differentiated thyroid cancer of follicular cell origin (DTC) after total thyroidectomy. The purpose of this investigation was to determine the accuracy of serum thyroglobulin levels in predicting persistent or recurrent DTC in euthyroid and hypothyroid patients.

METHODS

One hundred ninety consecutive patients with DTC of follicular cell origin who had 4 or more thyroglobulin levels measured after total thyroidectomy were retrospectively evaluated. One hundred fifteen patients had serum thyroglobulin levels measured when hypothyroid for radioiodine scanning or ablation. Serum thyroglobulin levels were determined by commercial assays. One hundred twenty-two patients less than 45 years old were considered at low risk, whereas 68 patients more than or equal to 45 years old were considered at high risk on the basis of TNM classification. The mean follow-up period was 62 months.

RESULTS

After thyroidectomy with or without central or modified radical neck dissection 120 patients had normal thyroglobulin levels (< or = 3 ng/mL) while receiving thyroid hormone. One hundred thirteen of the 120 patients (94%) with normal serum thyroglobulin levels had no evidence of recurrent tumor, whereas 6% (7 patients) had persistent or recurrent disease. Among 76 patients with persistent (28 patients) or recurrent (48 patients) disease, 70 had a serum thyroglobulin level > 3 ng/mL while receiving thyroid hormone. Overall, 14 of 115 patients, including 2 of 61 (3%) in the high-risk group and 12 of 54 (22%) in the low-risk group, only had elevated serum thyroglobulin levels when hypothyroid with high serum thyroid-stimulating hormone (TSH) levels documenting persistent or recurrent disease. In 1 patient the serum thyroglobulin level (240 ng/mL) was falsely elevated probably as a result of interfering antibodies because no tumor was identified surgically or pathologically, and the thyroglobulin concentration was < 3 ng/mL when analyzed in 3 other laboratories.

CONCLUSION

Serum thyroglobulin testing is sensitive (91%) and specific (99%) for identifying patients with persistent or recurrent differentiated thyroid cancer. Serum thyroglobulin levels are most precise when patients are hypothyroid (high TSH) and may be unreliable in patients with antithyroglobulin antibodies. We recommend TSH-stimulated thyroglobulin testing for all patients after total thyroidectomy for differentiated thyroid cancer of follicular cell origin regardless of patient age or risk group.

Brain metastases in patients with differentiated thyroid carcinoma

We present a retrospective review of six patients who developed brain metastases in our series of 649 with differentiated thyroid carcinoma seen at the Royal Marsden Hospital between 1936 and 1991. Prognosis was poor, with survival 1-19 months from the diagnosis of brain metastases in five patients. One patient remains alive at 18 months. A dosimetric approach may help to individualize and optimize treatment.

Thyroid antibodies in association with thyroid malignancy II: Qualitative properties of thyroglobulin antibodies

Qualitative properties of thyroglobulin (Tg) antibodies, in association with thyroid malignancy, suspected malignancy or other thyroid diseases, were studied in 177 patients. Retrospective clinical analysis revealed 137 patients to have thyroid carcinoma and 40 to have other thyroid diseases. Serum Tg was assayed by an immunoradiometric method. Thyroid microsomal (AMC) and Tg antibodies were measured by the particle agglutination method and the avidity of Tg antibodies by enzyme immunoassay (EIA). Assessment of the qualitative properties of Tg antibodies revealed that the high-avidity antibodies especially seem to bind circulating Tg. Thus any Tg value from a sample with detectable Tg antibodies is unreliable and should be interpreted with caution.

Serum thyroglobulin: an early indicator of autoimmune post-partum thyroiditis

OBJECTIVE

The aim of this study was to assess whether autoimmune thyroid damage in post-partum thyroiditis was accompanied by a significant rise in the concentration of thyroglobulin in the serum and whether its measurement could be useful in the prediction of the risk and severity of an episode of post-partum thyroid dysfunction.

PATIENTS

Fifty-one women, who had taken part in a larger survey of post-partum thyroiditis, were selected at random for this study. Fourteen women without elevated circulating thyroid autoantibodies and 21 with raised thyroid autoantibodies remained euthyroid throughout the post-partum year. A third group of 14 women had raised thyroid autoantibody levels and showed one or more episodes of thyroid dysfunction during the course of the first year post partum.

MEASUREMENTS

Thyroid autoantibodies were measured by ELISA, free T3 and free T4 by the Amerlex M method and TSH by an immunoradiometric method. Serum thyroglobulin was measured by a method free from interference by circulating endogenous thyroglobulin autoantibodies. Thyroid ultrasonography was performed using a General Electric RT3600 scanner operating at 7.5 MHz.

RESULTS

Fourteen control women had a mean serum thyroglobulin concentration of 3.3 micrograms/l (SD 4.4; range < 1-12 micrograms/l; 95% confidence interval up to 6.0 micrograms/l). Twenty-one thyroid autoantibody positive euthyroid women had a mean serum thyroglobulin level of 5.8 micrograms/l (SD 6.2; range < 1-36 micrograms/l) which was not significantly different from that seen in the control group. Sixteen thyroid autoantibody positive women who showed one or more episodes of thyroid dysfunction during the post-partum period had a mean serum thyroglobulin of 31 micrograms/l (SD 24.8; range up to 88 micrograms/l) and this was significantly elevated compared with both the control and antibody positive groups (P < 0.001). Serum thyroglobulin concentrations at 3 months post partum correlated with the degree of post-partum hypothyroidism (as indicated by the maximum TSH and the minimum free thyroxine concentrations post partum) and, in those cases where thyroid ultrasound examinations were performed, with the degree of lymphocytic infiltration of the thyroid gland.

CONCLUSIONS

The data presented in this paper confirm the destructive nature of post-partum thyroiditis and indicate that the measurement of serum thyroglobulin concentration could assist in the identification of those women at risk of post-partum thyroiditis.

Diagnosis, treatment, and outcome of follicular thyroid carcinoma

BACKGROUND

There have been numerous studies concerning the diagnosis, treatment, and prognosis of patients with papillary thyroid carcinoma, but relatively few addressing patients with follicular carcinoma.

METHODS

The authors analyzed their experience with 65 patients who underwent 96 thyroid operations for pure follicular thyroid carcinoma from 1956 to 1990.

RESULTS

The patients were 43 women and 22 men with a mean age of 45 years who were followed postoperatively for a mean of 10.4 years. Fifty-two patients (80%) were seen initially with a solitary thyroid nodule, and 24 (37%) had symptoms at presentation. Median tumor size was 2.2 cm. Fine-needle aspiration biopsy was performed in 20 patients, revealing a follicular neoplasm in 18 patients (90%) and an inadequate specimen in 2 patients. Nineteen patients received thyroid-stimulating hormone (TSH)-suppressive thyroid hormone therapy for an average of 4.5 months before surgery; tumor size remained the same in 10 patients (53%), increased in 5 (26%), and decreased in 2 (11%). At presentation, six patients had lymph node involvement, three had locally invasive tumors, and two had distant metastases. Initial operative treatment was lobectomy in 32 patients (49%), total thyroidectomy in 15 patients (23%), lobectomy plus contralateral partial or subtotal lobectomy in 11 patients (17%), and lesser procedures in 7 patients (11%). Twenty-nine patients had a completion total thyroidectomy, so that final surgical treatment consisted of total thyroidectomy in 44 patients (68%). Among 39 patients having intraoperative frozen section, only 3 (8%) were correctly diagnosed as having cancer. Permanent complications occurred during 3 of the 96 operations. Three patients (5%) have died of thyroid cancer (one with anaplastic transformation) since thyroidectomy, and two are living with distant metastatic disease.

CONCLUSIONS

Patients with follicular thyroid cancer, when first examined, usually have solitary thyroid nodules that are follicular neoplasms by aspiration cytology, and these nodules fail to regress in response to TSH-suppressive therapy. Frozen section rarely aids in management. The preferred treatment for follicular neoplasms is lobectomy followed by completion total thyroidectomy for histologically proven carcinomas larger than 1.0 cm. Total thyroidectomy allows use of thyroglobulin and radioiodine scanning to detect and treat metastatic disease. Complications of thyroidectomy were uncommon, and the mortality rate in treated patients was relatively low.

Serum thyroglobulin measurements in thyroid cancer: evaluation of 'false' positive results

OBJECTIVE

Serum thyroglobulin (Tg) should be undetectable in patients successfully treated for thyroid carcinoma. We have examined the course of disease in 19 patients with raised serum Tg (greater than 5 micrograms/l) on initial measurement but no other evidence of residual, recurrent or metastatic cancer.

DESIGN

416 patients from several centres were followed for periods between 1 and 9 years. Serum Tg was measured at 6-12-month intervals.

PATIENTS

All had differentiated thyroid cancer, treated by partial or total thyroidectomy and/or 131I ablation, and were receiving suppressive thyroxine therapy.

MEASUREMENT

Serum Tg was measured and clinical, X-ray and scan assessment made of presence or absence of residual, recurrent or metastatic cancer.

RESULTS

Of 416 patients initially assessed, only 19 had Tg greater than 5 micrograms/l but no clinical or radiological evidence of disease. At follow-up, 11 patients had developed overt signs of malignancy; one had been treated with 131I with a subsequent fall in Tg; five had Tg between 5 and 20 micrograms/l with incompletely suppressed TSH levels; two subjects remained with slightly elevated Tg and undetectable TSH.

CONCLUSION

Patients with elevated Tg require careful follow-up even in the apparent absence of disease. Moderate elevation of serum Tg may be due to inadequate thyroxine suppression therapy, assessed by detectable TSH values measured in a sensitive assay.

Effective laboratory evaluation of thyroid status

This article focuses on recent developments in thyroid-related laboratory tests, including analytical methods, clinical utility, and limitations of TSH, FT4, T4, FT3/T3, thyroglobulin, and thyroid autoantibodies and the effective use of these tests in the diagnosis of various forms of hypothyroidism or hyperthyroidism, and the management of patients undergoing T4 replacement, T4 suppression, or antithyroid drug therapy.

Usefulness of the combined antithyroglobulin antibodies and thyroglobulin assay in the follow-up of patients with differentiated thyroid cancer

A total of 1050 patients with differentiated thyroid cancer (DTC) have been followed in the Thyroid Center of Padua by means of serum thyroglobulin (Tg) measured with IRMA method and anti-Tg antibodies (TgAb) assays. Circulating TgAbs were detected in 102 (9.7%) patients. In 32 of these 102, TgAbs were evaluated before and after total thyroidectomy and 131I ablation. In these patients no relationship was found between preoperative serum TgAb levels on the one hand and tumor stage at diagnosis or outcome of the disease on the other. During the follow-up, TgAb serum levels decreased or disappeared in 21 cases considered tumor-free, while they remained unchanged or even increased, in comparison with the preoperative ones, in 11 patients, 5 with proven metastases and 6 considered tumor-free. Evaluating the whole group of 102 TgAb-positive patients, we observed that TgAb serum levels, measured after thyroid ablation, were significantly higher in cases with metastases than in those considered tumor-free (653.0 +/- 196.9 vs 157.7 +/- 116.5 U/ml, m +/- SD, p less than 0.0001). In the group of patients with metastases and circulating TgAbs, Tg serum levels were elevated in 27% of cases on TSH-suppressive therapy and in 44% off therapy when nodal metastases were present, and in 67% of cases on TSH-suppressive therapy and in 83% off therapy when distant metastases were present.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of serum thyroglobulin is of value in detecting tumour recurrence following treatment of differentiated thyroid carcinoma by lobectomy

Serum thyroglobulin was measured in 243 samples from 84 patients (20 men and 64 women, with a mean age of 48.9(14) years) with differentiated thyroid carcinoma treated by lobectomy, and in 58 patients treated by total thyroidectomy. Both groups were given thyroxine to suppress thyroid stimulating hormone (TSH). Three patients in the lobectomy group and eight in the thyroidectomy group had evidence of tumour recurrence. Serum thyroglobulin concentration was elevated in the presence of known recurrent tumour (P less than 0.001) irrespective of the type of operation, and in its absence tended to be higher in the lobectomy than in the thyroidectomy group (median 4 micrograms/l versus 2 micrograms/l, P less than 0.05). Serum thyroglobulin levels of less than 10 micrograms/l could confirm the absence of otherwise known tumour recurrence in both groups with a specificity of 100 per cent, and sensitivities of 80 per cent and 86 per cent in the lobectomy and thyroidectomy groups respectively. Exclusion of samples liable to spurious elevation of thyroglobulin improved the sensitivity in the lobectomy group to 92 per cent. Despite the presence of residual thyroid tissue, measurement of serum thyroglobulin can exclude the presence of significant metastases in most patients following lobectomy for thyroid carcinoma.

Clinical evaluation of serum thyroglobulin measurement using a commercial kit in the diagnosis of recurrent thyroid cancer

The value of serum thyroglobulin assay employing a kit manufactured by Diagnostic Products Corporation in the detection of recurrence of thyroid carcinoma in patients treated by thyroidectomy and ablative therapy was assessed by clinical follow-up and radioiodine scanning of 122 patients over a 2-year period. A total of 204 specimens were analysed. The assay was found to be sensitive and highly specific for the detection of recurrent thyroid carcinoma provided that lipemic sera are clarified by ultracentrifugation prior to measurement and that results from those patients who demonstrate positive serum antithyroglobulin antibodies are excluded. The predictive value of a serum thyroglobulin level above 20 pmol/L was 96% for recurrence of thyroid carcinoma. The predictive value for non-recurrence was 98% for serum thyroglobulin levels below 10 pmol/L. The specificity and sensitivity of the assay were poor for serum thyroglobulin levels between 10 and 20 pmol/L. In recurrence-free patients, the serum thyroglobulin levels were not changed by withdrawal of thyroid replacement therapy 4-7 weeks prior to sampling.

Serum thyroglobulin--its measurement and clinical use

Radioimmunoassays (RIA) have been shown to be unreliable in measuring serum thyroglobulin levels in patients with antithyroglobulin antibodies. The aim of this study was twofold. Firstly to compare the abilities of two immunoradiometric assays (IRMA), one commercially available, the other an 'in house' assay, with a conventional RIA. In addition the prognostic value of serum thyroglobulin levels in patients likely to relapse following a course of antithyroid drugs for Graves' disease was examined. The results obtained showed both of the IRMA methods to be unaffected by the presence of antithyroglobulin antibodies. Serum thyroglobulin levels were found to be poor predictors of relapse or remission following a 12 month course of antithyroid drugs.

Differentiated follicle-derived thyroid carcinoma in children

Fifteen patients, 11 females and 4 males, aged 4-16 years with follicle-derived differentiated thyroid carcinoma treated at the Helsinki University Central Hospital during 1953 through 1984 are reported. Histologically 13 carcinomata were papillary, 1 follicular and 1 was suspected to be follicular carcinoma (atypic adenoma). Eleven (73%) had cervical lymphnode metastases and 4 (25%) pulmonary metastases as well. All patients were initially operated on; total thyroidectomy was performed in 11 and subtotal in 4 patients. In 5 patients there was invasion into the thyroid capsule, perithyroid tissues and blood vessels; 4 patients with pulmonary metastases belonged to this group. Postoperatively 5 patients received radioactive iodine, 4 patients external irradiation to the neck and 6 were given both types of radiation. Pulmonary metastases were treated with radioactive iodine. The patients have been given suppressive doses of thyroxine. The follow-up ranged from 3.5 to 33 years. One patient with extensive pulmonary metastases died 6 years after the initial treatment, all others are still alive. Twelve patients have been followed for 9 to 33 years, in 10 serum thyroglobulin was determined. Tg was undetectable in 9 patients when measured during thyroxin therapy; in 1 patient followed for 33 years, the dose was not suppressive, and there were no signs of disease and Tg in the normal range. In 2 patients Tg could not be determined but they had no signs of disease 18 and 22 years after initial treatment. It is, therefore, presumed that these patients, forming 80% of the material, are cured. Two patients followed for 3.5 years are still under treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid nodules and thyroid cancer--diagnostic aspects

The clinical evaluation of patients with thyroid nodules is a common problem confronting the clinician. The vast majority of such nodules are benign, but concern that such a thyroid swelling may harbour malignancy demands prompt and accurate diagnosis. Furthermore, it is clear that properly treated differentiated thyroid carcinoma is associated with an excellent prognosis. The objective of investigating patients presenting with thyroid nodules is to define the small number of malignancies with minimum inconvenience to the patient in the most cost-effective way. There are no laboratory tests which reliably differentiate benign from malignant disease. The traditional approaches of radionuclide and ultrasound scanning have been shown to be poorly specific in the diagnosis of malignancy, resulting in many unnecessary operations for benign lesions. These tests have been replaced in many centres by fine needle aspiration cytology, with surgery for abnormal cytological findings alone. This technique is easily performed in an out-patient clinic and is well tolerated; accuracy in the diagnosis of thyroid neoplasia of up to 97% can be achieved.

Metabolic and thyroidal responses to mild cold are abnormal in obese diabetic women

Mild cold exposure (22 degrees C, with reference to 28 degrees C, thermoneutral) was studied by overnight whole-body indirect calorimetry in euthyroid women. Basal, sleeping, energy expenditure (EE) was significantly increased (+3.8%, P less than 0.05) in six normal weight women but reduced (-3.5%, P less than 0.05) in five obese type II diabetic women. Mixed responses were found in five women with simple obesity. Biochemical measurements were made on fasting blood samples taken at 0900 h after 12 h exposure to the two temperatures. Serum T4, free T3 and TSH were within the normal reference range in all subjects. Serum T4 did not show any differences between the groups, nor any effect from temperature. There was a significant increase in free T3 (P less than 0.05) at 22 degrees C in the control subjects, but no differences in the obese diabetic women. Serum thyroglobulin fell significantly in the diabetic group. Both TSH and free T3 responses to mild cold were significantly different between the groups, but both correlated positively (P less than 0.05) with the changes in sleeping energy expenditure at 22 degrees C with reference to 28 degrees C. Changes in TSH and free T3 were themselves significantly correlated within individuals (P less than 0.01). The normal physiological non-shivering thermogenesis of adult humans on exposure to a cool environment may thus be mediated by a pituitary-thyroid mechanism. The abnormal response of obese diabetic women was associated with impaired TSH and thyroid hormone responses, and may be a factor contributing to weight gain.

Serum thyroglobulin in the investigation of patients presenting with metastases

Serum thyroglobulin (Tg) is often very elevated in patients with metastatic thyroid carcinoma and, in 18 out of 40 patients examined, serum Tg was found to exceed 400 micrograms/l. In only two of 55 patients with benign nodular thyroid disease did serum Tg exceed 400 micrograms/l. In patients presenting with metastases of unknown origin, the finding of a very elevated serum Tg concentration may therefore be of value as an indicator that the metastases are due to thyroid carcinoma. During a period in which 128 new patients with differentiated thyroid carcinoma were seen, in five who presented with metastatic disease the initial estimation of serum Tg had proved useful in suggesting the thyroid origin of the metastases.

Serum thyroglobulin as a preclinical tumour marker in subgroups of thyroid cancer

Serum samples from a biological serum bank taken several years before the diagnosis of cancer, were analysed for S-Tg and S-TSH in 43 patients with thyroid cancer and compared to 128 healthy controls matched for age, sex, geographical region and time of blood sampling. The main finding was the difference in S-Tg between cases and controls, the highest values being found in sera from cases. Relative risk of thyroid cancer increases with increasing S-Tg levels (the global test giving P less than 0.0005). Extremely high levels were found in 4 cases with follicular and 3 with anaplastic cancers. No such statistically significant difference was found in S-TSH concentration. Possible explanations for the elevated S-Tg observed several years before clinically evident malignant tumour are discussed.

Serial serum thyroglobulin measurements in the management of differentiated thyroid carcinoma

Serum thyroglobulin (Tg) was measured on repeated occasions in 416 patients with differentiated thyroid cancer for up to 7 years after initial therapy. All patients had thyroidectomy and/or ablative 131I therapy and all measurements were done while patients were receiving T4 replacement. Tg was measured using a double-antibody radioimmunoassay. Overall correlation between serum Tg concentration and presence or absence of cancer was 95.9%. At the time of initial measurement 295 patients had serum Tg less than 5 micrograms/l, and in latest analysis only 1.7% of these patients showed evidence of disease. Initially there were 19 patients of a total of 121 with serum Tg greater than 5 micrograms/l in whom no cancer was apparent. In eight of these 19 subjects recurrent or metastatic disease has been diagnosed up to 3.5 years after the first measurement indicating that in these cases serum Tg values were 'predictive'. Serum Tg appears to be a sensitive and specific means of detecting residual, recurrent or metastatic thyroid cancer and in most situations can replace routine, expensive and inconvenient radioactive thyroid scans; these should be performed when serum Tg values are elevated or when there is clinical evidence suggesting recurrence.

Thyroglobulin production by malignant thyroid tumors. An immunocytochemical and radioimmunoassay study

Four hundred thirty surgical and biopsy specimens of malignant thyroid tumors of 323 patients were analyzed by histologic and immunocytochemical examination for their thyroglobulin (TG) content. Almost 95% of the differentiated thyroid carcinomas of follicular origin contained immunoreactive TG. The authors could not demonstrate TG in anaplastic carcinomas. Postoperative follow-up and serum TG determinations were available for 111 athyroid patients. Serum TG was elevated in five patients with metastatic or recurrent moderately differentiated follicular carcinoma, in two patients with metastasizing papillary, and in one patient with anaplastic carcinoma. Four patients had detectable serum TG levels without clinical and radiologic evidence of recurrence or metastases. In addition to conventional histologic examination, immunocytochemical demonstration of TG is a reliable and valuable aid in the diagnosis, classification, and determination of the grade of differentiation of malignant thyroid tumors. From this the pathologist can provide a pathologic basis for postoperative patient management.

Critical evaluation of serum thyroglobulin (Tg) levels during thyroid hormone suppression therapy versus Tg levels after hormone withdrawal and total body scan: results in 291 patients with thyroid cancer

Serum thyroglobulin (Tg) levels were measured during thyroid-hormone suppressive therapy in 291 patients who had been treated for well-differentiated thyroid carcinoma. The findings were compared with those of a subsequent total body scan (TBS) and with Tg levels measured after thyroid-hormone withdrawal. Of the patients with low Tg levels during suppressive therapy, 91.6% were subsequently shown to be free of disease or to have only remnants in the thyroid bed, whereas 8.4% had metastases (false-negative). Of the patients with false-negative findings, 89.3% had nodal metastases; 60.8% of the patients with nodal metastases exhibiting radioiodine uptake and only 23% of those with nonfunctioning nodal metastases had low Tg levels during suppression therapy. After thyroid-hormone withdrawal, all but 1 of the patients with nodal metastases had high Tg levels. All but 2 of the patients with distant metastases had high Tg levels during suppression therapy; 1 of these 2 patients exhibited high Tg levels after T3 withdrawal. No differences between Tg levels in patients with functioning and non-functioning metastases were found. Our study indicates that Tg assays performed during suppressive therapy have a fairly good predictive value and can be used as a general guide in the follow-up of thyroid cancer. However, since most differentiated metastases produce Tg only when stimulated by thyroid-stimulating hormone, measurements of Tg levels after the discontinuation of suppressive therapy would also seem to be necessary.

Abnormalities of thyroid function tests in hospital inpatients

Results of thyroid function tests were analysed in 199 clinically euthyroid inpatients with normal serum thyroid stimulating hormone values. Serum total triiodothyronine was less than 1.25 nmol/l in 61.8% of samples, free triiodothyronine less than 3.9 pmol/l in 57.8%, total thyroxine less than 63 nmol/l in 21.1% and free thyroxine less than 9.5 pmol/l in 17.6%. In contrast, thyroxine binding globulin ratio was below normal (less than 5) in only 5 samples. A significant positive correlation (P less than 0.001) of serum free thyroxine with total thyroxine, thyroxine/thyroxine binding globulin ratio and free triiodothyronine was present as well as a significant negative correlation (P less than 0.001) with serum thyroid stimulating hormone. There was no correlation of free thyroxine measurements with serum albumin or non-esterified fatty acid concentrations. Although serum free thyroxine is low in a number of patients with non-thyroidal illnesses, this does not appear to be due to a rise in non-esterified fatty acids or a fall in albumin as has been proposed. Serum thyroid stimulating hormone measurements are essential to confirm the diagnosis of hypothyroidism in such subjects.

Diagnostic value of a single serum thyroglobulin determination on and off thyroid suppressive therapy in the follow-up of patients with differentiated thyroid cancer

To assess the significance of a single serum thyroglobulin (Tg) determination on and off thyroid suppressive therapy, serum Tg measurements have been performed in 349 serum samples from 82 patients with differentiated thyroid cancer. All samples were collected after total thyroidectomy with or without subsequent ablation of residual thyroid tissue by radioiodine. One hundred and fifty-three samples were obtained while the patients were on thyroid suppressive therapy and 196 after withdrawal of medication. The results of serum Tg assays were analysed in relation to the presence or absence of residual or metastatic thyroid tissue, as assessed by clinical and laboratory evaluation, including 131I whole body scan. In patients with thyroid residue but no metastases, undetectable serum Tg (false negative results) occurred in 45% of cases off therapy and in 92.9% of cases during therapy. In the presence of metastases no undetectable serum Tg result was found in patients off therapy, while four (6.9%) out of 58 samples from patients with bone and/or lung metastases and seven (31.8%) out of 22 samples from patients with lymph node metastases alone were undetectable (falsely negative) during suppressive therapy. Serum Tg was undetectable in sera from patients with no evidence of thyroid residue or metastatic disease in all but one (1.7%) of 59 samples on and three (5.4%) of 56 samples off suppressive therapy. These Tg results were confirmed to be truly rather than falsely positive, since evidence of metastatic disease was obtained by whole body scan after the administration of therapeutic doses of 131I.(ABSTRACT TRUNCATED AT 250 WORDS)