Persistent or Recurrent Disease in Thyroid Cancer Survivors Who Have Elevated Serum Antithyroglobulin Antibodies.

OBJECTIVE: Detection of residual differentiated thyroid cancer is important but difficult. A variety of imaging modalities and biochemical markers has been used with moderately good success. We hypothesized that elevated perioperative serum antithyroglobulin antibody (TgAb) levels would also be a predictive marker for persistent or recurrent thyroid cancer. METHODS: We performed a retrospective analysis of 277 differentiated thyroid cancer survivors divided into 2 groups: (1) those with low or normal serum TgAb (TgAb-) and (2) those with elevated serum TgAb (TgAb+). All patients were seen at one major academic medical center. Patients were followed for a median of 7.54 years. RESULTS: Patients in the TgAb+ group were more likely to have positive lymph nodes at initial surgery, to be assigned to a higher American Joint Committee on Cancer stage, and to have significantly higher incidence of persistent/recurrent disease. The higher incidence of persistent/recurrent cancer was significant under univariable and multivariable (including TgAb status, age, and sex) Cox proportional hazards model analysis. CONCLUSION: We conclude that individuals with elevated serum TgAb at the outset should be followed with a higher index of suspicion for persistent/recurrent thyroid cancer.

On the Centennial of Vitamin D-Vitamin D, Inflammation, and Autoimmune Thyroiditis: A Web of Links and Implications.

The 100th anniversary of the discovery of vitamin D3 (VitD3) coincides with significant recent advances in understanding its mechanism of action along with accumulating knowledge concerning its genomic and nongenomic activities. A close relationship between VitD3 and the immune system, including both types of immunity, innate and adaptive, has been newly identified, while low levels of VitD3 have been implicated in the development of autoimmune thyroiditis (AIT). Active 1,25(OH)2 D3 is generated in immune cells via 1-α-hydroxylase, subsequently interacting with the VitD3 receptor to promote transcriptional and epigenomic responses in the same or adjacent cells. Despite considerable progress in deciphering the role of VitD3 in autoimmunity, its exact pathogenetic involvement remains to be elucidated. Finally, in the era of coronavirus disease 2019 (COVID-19), brief mention is made of the possible links between VitD3 deficiency and risks for severe COVID-19 disease. This review aims to commemorate the centennial of the discovery of VitD3 by updating our understanding of this important nutrient and by drawing up a framework of guidance for VitD3 supplementation, while emphasizing the necessity for personalized treatment in patients with autoimmune thyroid disease. A tailored approach based on the specific mechanisms underlying VitD3 deficiency in different diseases is recommended.

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).

Predictive Value of Serum Thyroglobulin for Structural Recurrence Following Lobectomy for Papillary Thyroid Carcinoma.

Background: The value of serum thyroglobulin/antithyroglobulin (Tg/antithyroglobulin antibody [ATg]) for papillary thyroid carcinoma (PTC) surveillance after lobectomy was investigated. We aimed to examine the association between postlobectomy serum Tg/ATg and PTC structural recurrence and define applicable values for stratification. Methods: PTC patients who underwent lobectomy with adequate serum Tg/ATg data during 2000-2014 were selected. Predictive classifiers of recurrence using random forest were established combining different variables related to serum Tg (ATg-negative patients) or ATg (ATg-positive patients). Cutoff values were determined with receiver operating characteristic curves when applicable. Kaplan-Meier curve and Cox regression were performed to examine the predictive value of elevated Tg/ATg. Results: Of 1451 patients enrolled, 66 (6.3%) and 26 (6.5%) patients in the ATg-negative group (n = 1050) and ATg-positive group (n = 401) developed recurrence. The established classifier of serum Tg (n = 1050) showed a favorable association with recurrence (AUC = 0.81), while serum ATg did not (AUC = 0.72). The optimal cutoff values of the first Tg (FTg, measured 6-12 months after lobectomy) and last Tg (LTg, measured most recently) were 5.3 and 11.0 ng/mL, respectively. Elevated LTg patients had significantly higher recurrence rates than normal LTg patients (23.5% vs. 4.4%, p < 0.05). Patients with elevated FTg had significantly lower recurrence-free survival rates than patients with normal FTg in all ATg-negative patients, low-risk patients, and intermediate- to high-risk patients (according to the American Thyroid Association initial risk stratification) (n = 1050, 583, and 467, all p < 0.05). Multivariate analysis indicated patients with elevated FTg had twice the recurrent risk compared with those with normal FTg (hazard ratio = 2.052). Conclusions: Postlobectomy serum Tg has favorable value for predicting recurrence in PTC patients, and reasonable thresholds could identify patients at higher risk for recurrence during follow-up.

Follow-up of patients with thyroid cancer and antithyroglobulin antibodies: a review for clinicians.

Antithyroglobulin antibodies (TgAb) are present in up to 25% of patients with differentiated thyroid carcinoma on initial postoperative assessment. Detectable concentrations of TgAb even below the manufacturer's cut-off can interfere with serum thyroglobulin (Tg) determination. When Tg is quantified using an immunometric assay (IMA) (hereafter referred to as Tg-IMA), this interference results in underestimated values of Tg. Although promising, more clinical trials evaluating the capacity of liquid chromatography/tandem mass spectrometry and of new assays to detect elevated Tg in patients with TgAb and structural disease are necessary, particularly when Tg is undetectable by a second-generation IMA (Tg-2GIMA). Neck ultrasonography (US) should be performed in patients submitted to total thyroidectomy and with negative Tg-IMA but with detectable TgAb more than 6 months after initial therapy. In patients treated with 131I, comparison of TgAb concentrations obtained before this treatment is useful to estimate the risk of disease and to guide the investigation. If initial assessment does not reveal any persistent tumor, the repetition of US is recommended while TgAb persist. Significant elevation of TgAb requires extended investigation. On the other hand, patients with negative Tg-IMA and US without abnormalities who exhibit a reduction > 50% in TgAb generally do not require investigation. Although TgAb can interfere with Tg, the management and follow-up of patients submitted to total thyroidectomy with borderline TgAb can probably be the same as those recommended for patients without TgAb if Tg-2GIMA and US indicate an excellent response to therapy. Currently, the presence/absence or the trend of TgAb levels cannot be considered in the follow-up of patients submitted to lobectomy.

Prevalence of Thyroid Autoimmunity in Women with Recurrent Pregnancy Loss.

Background and objectives: Thyroid autoimmunity (TAI) has been associated with a significantly increased risk of miscarriage in women with recurrent pregnancy loss (RPL). The aim of this study was to determine the prevalence of TAI in women with RPL and compare the clinical characteristics of positive and negative TAI women. Materials and Methods: This is a retrospective cross-sectional study; 203 women with RPL were included. Thyroid profile, anti-thyroid peroxidase (TPO-Ab), and anti-thyroglobulin (TG-Ab) antibodies were measured in all participants. Clinical characteristics and causes of RPL were compared between positive and negative TAI. Results: Prevalence of TAI was 14.8%; prevalence of positive TPO-Ab and TG-Ab was 12.3% and 4.9%, respectively. Women with TAI had significantly higher concentrations of thyrotropin (TSH) compared to women without TAI (4.8 ± 3.8 versus 3.1 ± 1.1, p = 0.001). There was no significant difference in age, the number of gestations, miscarriages, state of antiphospholipid antibodies (aPL), or causes of RPL between women that were TAI-positive versus TAI-negative. Prevalence of positive TAI by cause of RPL was: endocrine 7/25 (28%), genetic 1/5 (20%), autoimmune 1/5 (20%), anatomic 8/55 (14.5%), and unexplained cause 13/112 (11.6%). Conclusions: The prevalence of TAI in women with RPL is 14.8%. Women with an endocrine cause have the highest prevalence of TAI.

Efficacy of Low-Dose Radioiodine Ablation in Low- and Intermediate-Risk Differentiated Thyroid Cancer: A Retrospective Comparative Analysis.

(1) Background-low-dose radioiodine ablation is an accepted strategy for the treatment of low- and intermediate-risk thyroid carcinomas, although there is no international consensus. The aim of this study is to describe the clinical experience with low-dose radioiodine ablation in patients with low- and intermediate-risk thyroid cancer compared to high-dose ablation. (2) Methods-174 patients with low- and intermediate-risk thyroid cancer, 90 treated with low-dose ablation and 84 treated with high-dose ablation, were included. The primary endpoint was response to treatment one year after ablation, defined by stimulated thyroglobulin, whole body scan and ultrasound imaging. (3) Results-an excellent response rate of 79.8% in the low-dose group and 85.7% in the high-dose group was observed (p = 0.049). Stimulated thyroglobulin at the moment of ablation (p = 0.032) and positive antithyroglobulin antibodies (p < 0.001) were independent predictive factors for nonexcellent response. Young age (p = 0.023), intermediate initial recurrence risk (p < 0.001) and low-dose ablation (p = 0.004) were independent predictive factors for recurrence. (4) Conclusion-low-dose ablation seemed to be less effective than high-dose ablation, especially in those patients with positive antithyroglobulin antibodies or higher stimulated thyroglobulin levels at the moment of ablation. Low dose was associated with higher recurrence rates, and lower age and intermediate initial recurrence risk were independent risk factors for recurrence in our sample.

Utility of recombinant human TSH stimulation test in the follow-up of patients with differentiated thyroid cancer depending on basal thyroglobulin results.

Background: Thyroglobulin (Tg) is fundamental for differentiated thyroid cancer (DTC) monitoring. Tg detection can be enhanced using recombinant human thyroid-stimulating hormone (TSH) (rhTSH). This study is aimed to evaluate the use of the rhTSH stimulation test when using a high-sensitivity Tg assay. Methods: We retrospectively studied 181 rhTSH tests from 114 patients with DTC and negative for antithyroglobulin antibodies (anti-TgAb). Image studies were performed in all cases. Serum Tg and anti-TgAb were measured using specific immunoassays. Results: rhTSH stimulation in patients with basal serum Tg (b-Tg) concentrations lower than 0.2 ng/mL always resulted in rhTSH-stimulated serum Tg (s-Tg) concentrations lower than 1.0 ng/mL and negative structural disease. In patients with b-Tg concentration between 0.2 and 1.0 ng/mL, s-Tg detected one patient (1/30) who showed biochemical incomplete response. Patients with negative images had lower s-Tg than those with nonspecific or abnormal findings (p<0.05). Receiver operating characteristic curve analysis of the s-Tg to detect altered images showed an area under the curve of 0.763 (p<0.05). With an s-Tg cutoff of 0.85 ng/mL, the sensitivity was 100%, decreasing to 96.15% with an s-Tg cutoff of 2 ng/mL. Conclusions: Patients with DTC with b-Tg concentrations equal or higher than 0.2 ng/mL can benefit from the rhTSH stimulation test.

Dynamics of serum antithyroglobulin antibodies in patients with differentiated thyroid cancer.

PURPOSE: Serum antithyroglobulin antibodies (sTgAb) affect the reliability of Tg measurement in patients with thyroid cancer. We compared the outcome of patients with detectable and undetectable sTgAb, stratified according to the initial risk of recurrence (RR); also the response to treatment in patients with detectable sTgAb treated with total thyroidectomy (TT) with and without radioiodine remnant ablation (RA) and the sTgAb trend in the long-term follow-up according to the initial response. METHODS: We included 432 patients submitted to TT, with or without RA; 106 patients had detectable sTgAb levels. Median follow-up was 53 months. RESULTS: There were no statistically significant differences considering presentation between negative or positive sTgAb subjects. The frequency of structural incomplete response (SIR) in low, intermediate, and high RR was similar. Undetectable sTgAb in patients was achieved in a median of 16 months in ablated patients compared with 11 months in those without RA (p = 0.0232). Patients without RA had a higher rate of undetectable sTgAb during the first 12 months. A SIR was observed in 3% of patients with declining sTgAb, in 19% of those with stable levels, and in 43% with increasing sTgAb (p = 0.004). The status of no evidence of disease was achieved more frequently in patients with initial sTgAb levels < 200 mUI/l, independently of the initial RR. CONCLUSIONS: There was no impact of sTgAb on the initial clinical presentation and the response to therapy in low-risk patients treated with or without RA. sTgAb trend is more useful than an absolute value to predict a SIR.

In properly selected patients with differentiated thyroid cancer, antithyroglobulin antibodies decline after thyroidectomy and their sole presence should not be an indication for radioiodine ablation

ABSTRACT Objective Our objective was to evaluate the trend of antithyroglobulin antibodies (TgAb) during follow-up of patients with differentiated thyroid cancer (DTC) treated without RAI, as well as their role in the risk of recurrence. Subjects and methods This was a prospective, descriptive study. A total of 152 consecutive patients with DTC treated in a single institution undergoing total thyroidectomy without RAI and followed for a median of 2.3 years (0.5-10.3) were divided in two groups: TgAb(-) (n = 111) and TgAb(+) (n = 41). Patients were classified according to AJCC 7th and 8th editions, as well as to their risk of recurrence and response to treatment categories. Results Both groups, TgAb(-) and TgAb(+), were similar regarding patient and tumor characteristics. At the end of follow-up, 90 (59.2%), 57 (37.5%), 3 (2%) and 2 (1.3%) patients achieved excellent, indeterminate, biochemically incomplete and structurally incomplete response, respectively. The risk of structural recurrence was similar in both groups (TgAb[-] 0.9% vs. TgAb[+] 2.4%, p = 0.46). In the TgAb(+) group, TgAb became negative in 10 (24.4%), decreased ≥ 50% without negativization in 25 (60.9%), decreased < 50% in 4 (9.8%) and remained stable or increased in 2 (4.9%) cases. The only incomplete structural response had increasing TgAb during follow-up. Conclusions In properly selected patients with DTC, TgAb concentration immediately after total thyroidectomy should not mandate RAI ablation, and their trend during follow-up may impact the risk of recurrence.

Smoking Is Positively Associated with Antithyroperoxidase Antibodies and Antithyroglobulin Antibodies in Populations with Mildly Deficient Iodine Intake.

To evaluate the relationship between smoking and both antithyroperoxidase antibody (TPOAb) and antithyroglobulin antibody (TgAb) positivity in subjects from Panshan, Zhangwu, and Huanghua with mildly deficient, more than adequate, and excessive iodine intake, respectively. Smoking-related data were collected by questionnaire, and laboratory measurements of TPOAb, TgAb, and thyrotropin (TSH) were determined at baseline and follow-up. (1) A 1.48-fold increased risk of TPOAb positivity was found in smokers than in non-smokers after adjusting for confounders (age, sex, and areas) (OR[95% CI] = 1.48[1.12-1.95], p = 0.01). (2) Among female subjects, the prevalence of thyroid autoantibodies in smokers was increased than that in non-smokers in Panshan, Zhangwu, and Huanghua (TPOAb): 16.79 vs. 8.89%, 14.14 vs. 11.09%, 19.53 vs. 9.57%; TgAb 15.32 vs. 9.29%, 12.79 vs. 11.94%, 17.19 vs. 10.55%, respectively). The difference was significant in Panshan after adjusting for age. (3) Female long-term smokers (> 20 years) had an increased frequency of thyroid autoantibody positivity than non-smokers after adjusting for confounders (TPOAb OR[95% CI] = 1.60[1.10-2.34]; TgAb OR[95% CI] = 1.31[0.88-1.94]). (4) There was no difference in the incidence of thyroid autoantibodies among non-smokers, new smokers, and long-term smokers at follow-up. (5) TSH was greater in TPOAb-positive subjects than in seronegative smokers (1.56 vs. 1.20 mU/L, p < 0.001) and non-smokers (1.97 vs. 1.58 mU/L, p < 0.001). However, TSH was also greater in non-smokers than in smokers, regardless of whether subjects were positive (1.97 vs. 1.56 mU/L, p = 0.04) or negative (1.58 vs. 1.20 mU/L, p < 0.001) for TPOAb. Long-term smoking could increase the prevalence of thyroid autoantibodies in a population with mildly deficient iodine intake. TSH levels were lesser in smokers than in non-smokers and greater in subjects with thyroid autoantibody positivity than in seronegative subjects. The influence of smoking on TSH levels was independent of thyroid autoantibody levels.

Practice Variance in Thyroid Screening of Youth with Type 1 Diabetes Mellitus.

BACKGROUND: Variance between current American Diabetes Association (ADA) and International Society for Pediatric and Adolescent Diabetes (ISPAD) guidelines and in clinical practice exists for the use of thyroid antibody and thyroid function screening in pediatric patients with new-onset type 1 diabetes (T1D). METHODS: North American Pediatric Endocrine Society (PES) members were surveyed regarding their thyroid screening practices of euthyroid youth with T1D. An institutional analysis of the ability of antithyroid peroxidase (aTPO) and antithyroglobulin antibodies (aTG) to predict the subsequent use of levothyroxine was performed. RESULTS: Forty-eight percent of 374 survey respondents tested both aTPO and aTG at diagnosis of T1D, but 35% performed no baseline antibody testing. If antibodies were positive, 89% of the respondents would perform annual thyroid function testing, but if antibodies were negative, 62% would follow thyroid function annually and 29% biannually. Institutionally, aTPO had significantly greater sensitivity (p = 0.04) but lower specificity (p = 0.008) than aTG for predicting the use of levothyroxine. CONCLUSIONS: Variance exists among North American PES members regarding thyroid disease screening for pediatric patients diagnosed with T1D, and this appears to reflect differences between ADA and ISPAD guidelines. A prospective multicenter observational study which shares electronic medical record data and compares aTPO and TSH as primary screening tests may allow for more uniform guidelines and address the possibility of using TSH alone.

Immunoanalytical profile of thyroglobulin antibodies.

The anti-thyroglobulin autoantibodies are endogenous molecules directed against specific epitopes of thyroglobulin. These antibodies are linked to the autoimmune diseases or the differentiated thyroid cancer. The occurrence of anti-thyroglobulin autoantibodies may introduce inaccuracies in thyroglobulin quantification, causing over- or underestimation depending on the used method. Consequently, their determination is important to validate the thyroglobulin measurement. These antibodies are increasingly used for the diagnosis of cancer recidivies during post-surgical phase or for the treatment and monitoring of patient with differentiated thyroid cancer, while a continuing debate as regard their efficiency. Despite the elaboration of a reference material MRC 65/93 since forty years approximatively, discrepancies between techniques still reported in the literature. In this work, after a physiological and structural reminder of the anti-thyroglobulin autoantibodies, we will discuss the important points related to the both preanalytical and analytical steps.

Clinical Impact of Detectable Antithyroglobulin Antibodies Below the Reference Limit (Borderline) in Patients with Papillary Thyroid Carcinoma with Undetectable Serum Thyroglobulin and Normal Neck Ultrasonography After Ablation: A Prospective Study.

BACKGROUND: Interference of antithyroglobulin antibodies (TgAb) with serum thyroglobulin (Tg) can occur even at detectable TgAb concentrations below the reference limit (borderline TgAb). Thus, borderline TgAb is considered as TgAb positivity in patients with thyroid cancer. This prospective study evaluated patients with papillary thyroid carcinoma with undetectable Tg and normal neck ultrasonography (US) after total thyroidectomy and ablation with 131I, and compared tumor persistence/recurrence and long-term Tg and TgAb behavior in those with borderline versus undetectable TgAb. METHODS: A total of 576 patients were evaluated, divided into two groups: group A with undetectable TgAb (n = 420), and group B with borderline TgAb (n = 156). RESULTS: Groups A and B were similar in terms of patient and tumor characteristics. The time of follow-up ranged from 24 to 120 months. During follow-up, 11 (2.6%) patients in group A and 5 (3.2%) in group B developed a recurrence (p = 0.77). In group A, recurrences occurred in 9/390 patients who continued to have undetectable TgAb and in 1/9 patients who progressed to borderline TgAb. In group B, recurrences were detected in 1/84 patients who progressed to have undetectable TgAb, in 1/45 who still had borderline TgAb, and in 3/12 who developed elevated TgAb. In the presence of Tg levels <0.2 ng/mL, recurrences were detected in 2/486 patients with undetectable TgAb, in 0/67 with borderline TgAb, and in 3/12 with elevated TgAb. The results of post-therapy whole-body scanning (RxWBS) of 216 patients with Tg ≤0.2 ng/mL and normal US at the time of ablation were also analyzed. In low-risk patients, none of the 40 patients with borderline TgAb and none of the 94 with undetectable TgAb exhibited ectopic uptake on RxWBS. In intermediate-risk patients, lymph node metastases were detected by RxWBS in 1/25 (4%) with borderline TgAb and in 2/57 (3.5%) with undetectable TgAb. CONCLUSIONS: The results suggest that among low- or intermediate-risk patients with undetectable Tg and normal US after thyroidectomy, those with borderline TgAb are at no greater risk of tumor persistence or recurrence than those with undetectable TgAb. When undetectable Tg levels persist, recurrence should be suspected in the case of a TgAb elevation above the reference limit.

Associations between Systemic Sclerosis and Thyroid Diseases.

We have reviewed scientific literature about the association of systemic sclerosis (SSc) and thyroid disorders. A high incidence, and prevalence, of new cases of autoimmune thyroiditis (AT) and/or hypothyroidism have been shown in sclerodermic patients (overall in the female gender). An association among a Th1 immune-predominance, low vitamin D levels, and AT have been also shown in SSc patients. Cases of Graves' disease (GD) have been described in SSc patients, too, according with the higher prevalence of thyroid autoimmunity. It has been also shown a higher prevalence of papillary thyroid cancer (PTC), in association with AT, in SSc patients. However, in order to confirm results about GD and thyroid cancer, studies in larger number of patients with SSc are needed. During the follow-up of SSc patients it would be appropriate to monitor carefully their thyroid status. The abovementioned data strongly suggest a periodic thyroid function follow-up in female SSc patients [showing a borderline high (although in the normal range) thyroid-stimulating hormone level, antithyroid peroxidase antibody positivity, and a small thyroid with a hypoechoic pattern], and, when necessary, appropriate treatments. In conclusion, most of the studies show an association among SSc, AT, and hypothyroidism, such as an increased prevalence of TC overall in SSc patients with AT. Only few cases of GD have been also described in SSc.

Thyroglobulin Liquid Chromatography-Tandem Mass Spectrometry Has a Low Sensitivity for Detecting Structural Disease in Patients with Antithyroglobulin Antibodies.

BACKGROUND: Thyroglobulin (Tg) measurement in patients with positive antithyroglobulin antibodies (anti-TgAbs) is not reliable. Tg measurement using liquid chromatography-tandem mass spectrometry (LC/MS) may be useful in this setting. METHODS: This is a retrospective study with the objective of determining the accuracy of Tg-LC/MS in patients with thyroid cancer with anti-TgAbs. All patients with follicular cell-derived thyroid cancer (TC) who had thyroglobulin measured using LC/MS assay from November 1, 2013, to November 7, 2014, were evaluated. The frequency of detectable Tg-LC/MS was evaluated, with a functional sensitivity (FS) of 0.5 ng/mL in patients with structural disease. Then performance of Tg-LC/MS versus Tg immunometric assay (IMA) was compared using either Immulite assay (Tg-1) with a FS of 0.9 ng/mL or Beckman assay (Tg-B) with a FS of 0.1 ng/mL in detecting structural disease in patients with positive anti-TgAbs. RESULTS: A total of 154 consecutive patients were included in this evaluation. Of these, 116 (75%) patients were positive for anti-TgAbs. In patients with structural disease and positive anti-TgAbs, Tg-LC/MS was undetectable in 43.7% of patients. Then the diagnostic accuracy for structural disease of Tg-LC/MS was compared with each Tg-IMA assay separately. In the 26 patients with positive anti-TgAbs where a Tg-I assay was used, the sensitivity and specificity for detecting structural disease were 33.3% and 88.2%, respectively, for the Tg-I assay, and 44.4% and 94.1%, respectively, for the Tg-LC/MS assay. In the 74 patients with positive anti-TgAbs where Tg-B was used, the sensitivity and specificity for detection of structural disease were 72.7% and 71.4%, respectively, for the Tg-B assay, and 62.6% and 93.7%, respectively, for the Tg-LC/MS assay. CONCLUSION: In patients with thyroid cancer with positive anti-TgAbs, Tg-LC/MS was frequently undetectable and was less sensitive for detecting disease than a Tg assay was with a functional sensitivity of 0.1 ng/mL. For patients with detectable Tg-LC/MS and anti-TgAbs, use of the assay for monitoring requires further prospective studies.

Prevalencia de anticuerpos antiperoxidasa y antitiroglobulina en jóvenes con hipotiroidismo subclínico y clínico / Prevalence of antiperoxidase and antithyroglobulin antibodies in young people with clinical and subclinical hypothyroidism

Introducción: El diagnóstico temprano de hipotiroidismosubclínico y el hallazgo de anticuerpos antitiroideos son de granvalor para el estudio de las enfermedades tiroideas. Objetivos: determinarla prevalencia de anticuerpos antitiroideos en hombres ymujeres jóvenes con hipotiroidismo subclínico y clínico, y compararsu frecuencia entre ambos sexos. Materiales y métodos: se estudiaron280 estudiantes de la Universidad Antonio Nariño, en laciudad de Bogotá, entre los 18 y 30 años. A los participantes en elestudio se les realizó TSH y T4 libre por quimioluminiscencia parala identificación de casos de hipotiroidismo subclínico y clínico. Atodos los individuos con alteraciones en las pruebas de función tiroidease les realizaron anticuerpos antitiroideos antiperoxidasa yantitiroglobulina por microelisa. Resultados: se encontró una altaprevalencia de anticuerpos antitiroideos antiperoxidasa y antitiroglobulinaen los jóvenes que presentaron hipotiroidismo, y unaprevalencia de hipotiroidismo en jóvenes de 4,64%, sin encontrarsediferencias estadísticamente significativas entre hombres y mujeres.Conclusión: existe en la población de jóvenes estudiados conhipotiroidismo subclínico una alta prevalencia de anticuerpos quesugerirían causa autoinmune en nuestra población universitaria. Sedeben realizar ensayos clínicos adicionales que permitan investigarotras posibles causas de hipotiroidismo como postinfecciosas, tóxicasy medioambientales, así mismo una posible asociación de estapatología con otras condiciones autoinmunes.

Abstract: Introduction: An early diagnosis of subclinical hypothy-roidism and the discovery of antithyroid antibodies are really valu-able in preventing severe thyroid diseases. Objectives: To determine the prevalence of antithyroid antibodies in young men and women with subclinical and clinical hypothyroidism, and to compare their frequency among both genders. Materials and methods: The case study enrolled 280 students between 18 and 30 years of age from the Antonio Nariño University in Bogotá. TSH and free T4 was deter-mined by chemoluminescence in all participants of the study for the identification of possible clinical and subclinical hypothyroidism. All individuals with alterations in their thyroid function tests had also their antiperoxidase and antithyroglobulin antibodies as-sessed by microelisa. Results: A high prevalence of antiperoxi-dase and antithyroglobulin antithyroid antibodies was detected in young people who had hypothyroidism, and the prevalence of hypothyroidism in young people was 4,64%. No statistically sig-nificant difference was found between the prevalence in men and women. Conclusion: There was a high prevalence of antibodies in the study population of young people with subclinical hypo-thyroidism, which could suggest an autoimmune cause in our university population. It is also necessary to carry out other clini-cal trials which could allow the investigation of possible causes of hypothyroidism like post-infectious, toxic and environmental and also a possible association between this disease and other autoimmune conditions.

Thyroid autoantibody measurement by enzyme immunoassay.

Thyroid antibodies are commonly utilized in the assessment and diagnosis of autoimmune thyroid disorders. We compared the measurements of antithyroglobulin and antithyroidperoxidase antibodies by enzyme immunoassay with that of the conventional agglutination method. This fully automated enzyme immunoassay is more specific and cost effective than the agglutination method. Further this is a very quantitative and rapid method producing results in two hours as compared to at least twenty=four hours required by the conventional method. Antithyroidperoxidase antibodies determined by enzyme immunoassay are more specific and sensitive in the diagnosis of Hashimoto's thyroiditis than the antithyroglobulin antibodies.