Lack of association between high serum thyroid-stimulating hormone level and risk of papillary thyroid microcarcinomas

A meta-analysis of the value of serum TSH concentration in the diagnosis of differentiated thyroid cancer in patients with thyroid nodules

Background

In recent years, most studies believe that high TSH level is positively correlated with the incidence of thyroid cancer, but it is still controversial. For this reason, the purpose of this study is to analyze the correlation between preoperative TSH level and thyroid malignant nodules using pathological diagnosis as the gold standard. To evaluate the role of serum TSH in predicting malignancy of thyroid nodules with uncertain cytology.As an important member of the hypothalamus-pituitary-thyroid axis in the endocrine system, TSH plays a crucial role in regulating the growth, differentiation, and function of thyroid cells (Zhang et al., 2023) [1]. Therefore, it has always been considered closely related to TC. Currently, most studies have compared the TSH levels of TC patients and individuals with benign thyroid disease or healthy controls. These findings from various studies indicated that TC patients often demonstrate elevated TSH levels, even when their TSH falls within the normal range. However, it is important to highlight that the current evidence primarily relies on cross-sectional studies, which mainly describe a phenomenon without establishing causal relationships. The involvement of TSH in the early onset or late progression of TC remains unknown, the interaction between TSH and other factors and how it affects TC is not well understood (Gubbi et al., 2020) [2].Symptoms of thyroid cancer are usually insidious, and early thyroid cancer often has no obvious clinical symptoms. Therefore, early detection and early treatment are particularly important, and how to improve the preoperative diagnosis rate of thyroid nodules is also a problem that clinicians pay close attention to.

Objective

To evaluate the value of serum TSH concentration in the diagnosis of differentiated thyroid carcinoma in patients with thyroid nodules.

Methods

Our study searched databases in both Chinese and English.China Academic Journals FULL-text Database (CNKI), China Online Journals, Chinese Scientific Journals database and Chinese Biomedical Literature Database (CBM) were searched by computer. The English literature was established by PubMed, Embase, Cochrane Library, Web of Science and other databases until June 2022 to search for relevant literatures on the diagnostic test of serum TSH concentration in patients with thyroid nodule. The literatures that met the criteria were screened, the data were extracted, and the literature quality was evaluated. The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio of the method for the diagnosis of differentiated thyroid carcinoma were calculated and summarized. The receiver operating characteristic (SROC) curve was drawn and the area under the curve was obtained.

Results

A total of 23 diagnostic tests were included (5348 lesions). Meta-analysis showed that the combined sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio of serum TSH concentration in the diagnosis of differentiated thyroid carcinoma were 0.64, 0.72, 2.511, 0.386 and 7.14, respectively. The area under SROC curve (AUC) was 0.79, and the Q index was 0.7283, indicating no statistically significant difference.

Conclusion

Based on current evidence, detection of serum TSH concentration in thyroid nodule patients has high sensitivity and specificity for the diagnosis of differentiated thyroid cancer, which has good clinical application value. However, other auxiliary examinations are still needed to improve the diagnosis rate.

The Relationship between Thyrotropin Serum Concentrations and Thyroid Carcinoma

Thyroid Stimulating Hormone (TSH) is a hormone secreted by the pituitary gland and plays a role in regulating the production and secretion of thyroid hormones by the thyroid gland. This precise feedback loop is essential for maintaining a harmonious balance of thyroid hormones in the body, which are vital for numerous physiological processes. Consequently, TSH serves as a significant marker in assessing thyroid function, and deviations from normal TSH levels may indicate the presence of a thyroid disorder. Thyroid cancer (TC) is the malignant tumor within the endocrine system. In recent years, numerous experts have dedicated their efforts to discovering efficacious biomarkers for TC. These biomarkers aim to improve the accurate identification of tumors with a poor prognosis, as well as facilitate active monitoring of tumors with a more favorable prognosis. The role of TSH in the thyroid gland underscores its potential influence on the occurrence and progression of TC, which has garnered attention in the scientific community. However, due to the limited scope of clinical research and the dearth of high-quality foundational studies, the precise impact of TSH on TC remains unclear. Consequently, we present a comprehensive review of this subject, aiming to offer a valuable reference for future research endeavors.

The association between thyroid-stimulating hormone and thyroid nodules, goiter and thyroid antibody positivity

Background

The relationship between normal thyroid-stimulating hormone (TSH) levels and thyroid disease in adults remains controversial. This study aimed to investigate the correlation between serum TSH levels, particularly those falling within the normal range, and thyroid diseases in Chinese adults, including thyroid nodules (TN), goiter (GR), and thyroid antibody positivity.

Materials and methods

This research was a cross-sectional study conducted in an adult population in Tianjin, China. Thyroid volume (Tvol) and TN were assessed using thyroid ultrasonography. Fasting venous blood and spot urine samples were collected to evaluate thyroid function and iodine status.

Results

A total of 2460 subjects participated in the survey. The prevalence of thyroid dysfunction was 9.76%, and abnormal TSH levels were found to potentially increase the risk of GR and thyroid antibody positivity in adults. A total of 2220 subjects with TSH within the normal reference range were included in the further study. In these patients, Tvol decreased as TSH levels increased, in both men and women (P < 0.0001). Low TSH levels (0.27-1.41 IU/mL) were identified as a risk factor for TN (odds ratio [OR], 1.46; 95% CI: 1.14-1.87) and GR (OR 5.90, 95% CI 2.27-15.3). Upon stratification by sex and age, the risk of TN was found to be higher in women and elderly individuals (≥60 years old), while the risk of GR was found to be higher in men and younger individuals (<60 years old). High TSH levels (2.55-4.2 IU/mL) were identified as a risk factor for thyroid antibody positivity (OR, 1.53; 95% CI: 1.11-2.10). Men and younger individuals with high TSH levels exhibited a higher risk of thyroid antibody positivity.

Conclusion

In adults with normal TSH levels, low TSH levels were associated with an increased risk of TN and GR, whereas high TSH levels were associated with thyroid antibody positivity. The research also suggests that adults whose TSH levels at upper or lower limits of the normal range should be reviewed regularly.

Association between thyroid stimulating hormone levels and papillary thyroid cancer risk: A meta-analysis

High thyroid stimulating hormone (TSH) levels may stimulate papillary thyroid cancer (PTC) cell proliferation; however, the relationship between TSH levels and PTC risk remains controversial. We aim to ascertain the association through a meta-analysis. Literature searches were conducted in PubMed, Embase, and Web of Science databases. After literature screening, the methodological quality was assessed using the Newcastle-Ottawa Scale and Agency for Healthcare Research and Quality methods. Cochran's Q and I 2 tests were used to evaluate heterogeneity in the meta-analysis. Egger's test was applied to assess publication bias. A total of 12 eligible studies were included in this meta-analysis; all were of moderate and high methodological quality. The pooled results suggested that increased TSH levels were significantly associated with PTC risk; however, the included studies were significantly heterogeneous. Stratification analysis indicated that the heterogeneity might be from the area or type of control. Although significant publication bias existed among the studies, the trim-and-fill method and sensitivity analysis revealed that the combined results were stable and robust. TSH levels are significantly associated with the PTC risk; however, more high-quality studies in large sample sizes are recommended to verify the extrapolation of these findings.

The associations between thyroid-related hormones and the risk of thyroid cancer: An overall and dose-response meta-analysis

Objective

Thyroid cancer (TC) is one of the most common malignant tumours of the endocrine system. Thyroid-stimulating hormone (TSH) is known as being a risk factor for TC, but other thyroid-related hormones are inconsistently associated with TC. The purpose of this study was to comprehensively evaluate the relationships between thyroid-related hormones and the risk of TC.

Methods

This study utilized searches of PubMed, Embase, Web of Science and Cochrane library up to the date of March 31st, 2022. Additionally, we performed a systematic review of related original studies combining overall and dose-response meta-analyses.

Results

A total of 30, 5 and 7 articles were included in the meta-analyses of TSH, Free triiodothyronine (FT3), free thyroxine (FT4) and TC risk with 58437, 6813 and 7118 participants respectively. An increased risk of TC was associated with high TSH exposure (OR=1.28, 95% CI: 1.19-1.37, P < 0.001) in the overall meta-analysis. For every 1 mU/L increase in TSH, the risk of TC increased by 16%. However, in those studies that used healthy subjects as controls, the association was not statistically significant(P=0.62). Additionally, high serum FT3 demonstrated a reduced risk of TC, with a combined OR of 0.86 in the fixed-effect model (95% CI: 0.81-0.90, P < 0.001). In addition, a statistically significant increase in TC risk was found when FT4 concentrations reached a certain threshold (approximately 2.2 ng/dL) in the dose-response meta-analysis.

Conclusions

Significant associations between thyroid-related hormones and the risk of TC were found in this study. Further research is needed to understand the underlying mechanisms.

Causal associations of thyroid function and dysfunction with overall, breast and thyroid cancer: A two-sample Mendelian randomization study

Whether thyroid dysfunction plays a causal role in the development of cancer remains inconclusive. We conducted a two-sample Mendelian randomization study to investigate the associations between genetic predisposition to thyroid dysfunction and 22 site-specific cancers. Single-nucleotide polymorphisms associated with four traits of thyroid function were selected from a genome-wide association meta-analysis with up to 72,167 European-descent individuals. Summary-level data for breast cancer and 21 other cancers were extracted from the Breast Cancer Association Consortium (122,977 breast cancer cases and 105,974 controls) and UK Biobank (367,643 individuals). For breast cancer, a meta-analysis was performed using data from both sources. Genetically predicted thyroid dysfunction was associated with breast cancer, with similar patterns of associations in the Breast Cancer Association Consortium and UK Biobank. The combined odds ratios of breast cancer were 0.94 (0.91-0.98; p = 0.007) per genetically predicted one standard deviation increase in TSH levels, 0.96 (0.91-1.00; p = 0.053) for genetic predisposition to hypothyroidism, 1.04 (1.01-1.07; p = 0.005) for genetic predisposition to hyperthyroidism and 1.07 (1.02-1.12; p = 0.003) per genetically predicted one standard deviation increase in free thyroxine levels. Genetically predicted TSH levels and hypothyroidism were inversely with thyroid cancer; the odds ratios were 0.47 (0.30-0.73; p = 0.001) and 0.70 (0.51-0.98; p = 0.038), respectively. Our study provides evidence of a causal association between thyroid dysfunction and breast cancer (mainly ER-positive tumors) risk. The role of TSH and hypothyroidism for thyroid cancer and the associations between thyroid dysfunction and other cancers need further exploration.

The association of preoperative thyroid-stimulating hormone level and the risk of differentiated thyroid cancer in patients with thyroid nodules: A systematic review and meta-analysis

BACKGROUND

This systematic review and meta-analysis was conducted to determine the value of preoperative thyroid-stimulating hormone (TSH) levels in assessing the risk of differentiated thyroid cancer (DTC) in patients with thyroid nodules.

METHODS

This meta-analysis included 23,799 subjects (15,406 non-Chinese and 8,393 Chinese) with thyroid nodules. Multivariate and individual adjusted odds ratios (OR) were calculated for a 1 mU/L increase in preoperative TSH levels to determine the risk of malignant DTC.

RESULTS

The OR for DTC in relation to preoperative TSH levels was significant in Chinese (1.25 [1.11, 1.40], Z = 3.67, p = 0.0002) and non-Chinese subjects (1.12 [1.03, 1.22], Z = 2.72, p = 0.006). The overall random-effects model indicated that there was a significantly increased risk for DTC in patients with thyroid nodules (OR 1.16 [1.06, 1.27], Z = 3.29, p = 0.007).

CONCLUSIONS

A significant association between higher TSH levels and risk of DTC was observed in both population groups investigated, with higher ORs for Chinese subjects.

Is serum TSH a biomarker of thyroid carcinoma in patients residing in a mildly iodine-deficient area?

PURPOSE

To investigate the association between the pre-operative serum TSH (s-TSH) level and differentiated thyroid carcinoma (DTC) in a mildly iodine-deficient area.

METHODS

Patients undergoing surgery for thyroid nodular disease (TND) were included from three tertiary surgical departments. Data were collected from a national thyroid surgery database (THYKIR) and from patient charts. Individuals with overtly coexisting thyroid disorders were excluded for subgroup analyses. Patients were compared with the Danish background population, employing previous data from DanThyr, a study initiated to monitor the iodine fortification program in Denmark.

RESULTS

Nine-hundred ninety-eight patients [cases/controls: 265/733; female/male: 794/204; age (mean ± SD): 51 ± 15 years] were included. S-TSH was significantly higher in the DTC group [median (IQR): 1.3 (0.9-1.9 mIU/L)] compared with the benign TND group [0.9 (0.6-1.5 mIU/L)] (p < 0.0001). The median s-TSH in the background population was similar to that found among DTC patients (p = 1.00), but markedly higher than the s-TSH level in the benign TND group (p < 0.0001). There was no association between s-TSH and DTC disease stage (p = 0.08-0.87).

CONCLUSIONS

s-TSH was significantly higher in patients with DTC than in those with benign TND. However, this difference can be explained by abnormally lower s-TSH level in the latter group, probably caused by subtle nodular functional autonomy. Due to the huge overlap and the small difference in median s-TSH between patients with benign and malignant TND, s-TSH is not suitable as a biomarker of DTC in a clinical setting.

High Urinary Iodine, Thyroid Autoantibodies, and Thyroid-Stimulating Hormone for Papillary Thyroid Cancer Risk

Thyroid nodules have become a common clinical problem, and the clinical importance of thyroid nodules lies in the determination of thyroid cancer. This study aims to evaluate the risk factors for papillary thyroid cancer (PTC) with regard to urinary iodine concentration (UIC), thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TGAb) in comparison to thyroid nodular goiter (NG). Among the 2041 patients, 43.8% of which showed more than adequate (UIC 200-299 μg/L) and excessive iodine (UIC ≥ 300.0 μg/L) status. Compared with adequate iodine intake, iodine deficiency (UIC < 100 μg/L) was inversely associated with multifocality (OR 0.59, P = 0.040), while more than adequate iodine intake was independently associated with an increased risk of larger tumor size (OR 1.33, P = 0.002) in female PTC patients but not in males. No significant difference in UIC was observed between patients with PTC and NG, suggesting that high iodine intake may be related with the growth of PTC, but not with its oncogenesis. Besides, positive for TPOAb and TGAb were individually associated with papillary thyroid microcarcinoma (PTMC) risk (OR 2.05 and 1.71, respectively, both P < 0.05) in female patients with tumor foci < 1 cm but not in males. Furthermore, younger age (< 46 years), TGAb positivity and small thyroid nodules in both sexes, higher TSH, TPOAb positivity, and multifocality in females could all predict PTC risk (all P < 0.05). These results might have clinical significance for managing patients with thyroid nodules and those with thyroidectomy.

TSH increment and the risk of incident type 2 diabetes mellitus in euthyroid subjects

PURPOSE

Thyroid function is known to influence glucose metabolism, and thyroid-stimulating hormone is the most useful parameter in screening for thyroid dysfunction. Therefore, the aim of this study was to investigate the incidence of type 2 diabetes according to baseline thyroid-stimulating hormone level and thyroid-stimulating hormone change in euthyroid subjects.

METHODS

We identified and enrolled 17,061 euthyroid subjects without diabetes among participants who had undergone consecutive thyroid function tests between 2006 and 2012 as a part of yearly health check-up program. Thyroid-stimulating hormone changes were determined by subtracting baseline thyroid-stimulating hormone level from thyroid-stimulating hormone level at 1 year before diagnosis of diabetes or at the end of follow-up in subjects who did not develope diabetes.

RESULTS

During 84,595 person-years of follow-up, there were 956 new cases of type 2 diabetes. Cox proportional hazards models showed the risk of incident type 2 diabetes was significantly increased with each 1 μIU/mL increment in TSH after adjustment for multiple confounding factors (hazard ratio = 1.13, 95% confidence interval: 1.07-1.20, P < 0.001). Compared with individuals in the lowest tertile (-4.08 to 0.34 μIU/mL), those in the highest thyroid-stimulating hormone change tertile (0.41-10.84 μIU/mL) were at greater risk for incident type 2 diabetes (hazard ratio = 1.25, 95% confidence interval: 1.05-1.48, P for trend = 0.011). However, baseline thyroid-stimulating hormone level and tertile were not associated with the risk for diabetes.

CONCLUSIONS

Prominent increase in thyroid-stimulating hormone concentration can be an additional risk factor for the development of type 2 diabetes in euthyroid subjects.

The effect of TSH change per year on the risk of incident chronic kidney disease in euthyroid subjects

The objective of this study is to evaluate the predictive values of baseline thyroid-stimulating hormone and the rate of thyroid-stimulating hormone change within the euthyroid state on the development of chronic kidney disease. We conducted a longitudinal study in 17,067 Korean adults with normal thyroid function and no history of thyroid disease. Incident chronic kidney disease was defined as an estimated glomerular filtration rate <60 ml/min/1.73 m². The rate of thyroid-stimulating hormone change was determined by subtracting the baseline thyroid-stimulating hormone level from the thyroid-stimulating hormone level measured at the last visit prior to the diagnosis of chronic kidney disease or at the final visit in subjects without chronic kidney disease, divided by the observation period (years). Subjects were stratified into quintiles according to rates of thyroid-stimulating hormone change. During 86,583 person-years of follow-up (median follow-up 5.2 years), there were 561 incident cases of chronic kidney disease. The risk of incident chronic kidney disease was significantly higher in subjects with rapid increases (quintile 5) or decreases (quintile 1) in thyroid-stimulating hormone levels compared to the reference group (quintile 3). In fully adjusted models, the hazard ratios of quintiles 1 and 5 were 3.15 (95 % confidence interval 2.34 to 4.24; p < 0.001) and 3.37 (95 % confidence interval 2.52 to 4.51; p < 0.001), respectively. However, there was no significant association between baseline thyroid-stimulating hormone and risk of incident chronic kidney disease. The development of chronic kidney disease is associated with the rate of changes in thyroid-stimulating hormone level rather than with baseline thyroid-stimulating hormone levels.

The Association of Thyrotropin and Autoimmune Thyroid Disease in Developing Papillary Thyroid Cancer

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common type of malignant thyroid neoplasm. However, the incidence of PTC with autoimmune thyroid disease (AITD) varies between studies. This study aims to investigate whether patients with AITD have increased incidence of PTC. We also analyzed the relationship of serum thyroid-stimulating hormone (TSH) levels and PTC in relation to AITD based on histopathological data.

METHODS

A total of 533 participants who underwent thyroidectomy were enrolled in this retrospective study based on clinicohistopathological data and known thyroid autoantibodies. Patients were divided into PTC and benign groups according to histopathologic diagnosis. Age, gender, body mass index, and serum TSH level before thyroidectomy were recorded.

RESULTS

Of the 533 enrolled patients, 159 (29.8%) were diagnosed with PTC, of which 38 (35.5%) had Hashimoto's thyroiditis (HT). More patients with HT were female, and patients with HT, Graves' disease, and thyroid nodules with higher TSH level had a higher incidence of PTC.

CONCLUSIONS

A high proportion of the patients with PTC had HT. There was a trend that a higher serum TSH level was associated with a greater risk of thyroid cancer.

Vascular endothelial growth factor G+405C polymorphism may contribute to the risk of developing papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common endocrine malignancy. Vascular endothelial growth factor (VEGF) is a mediator implicated with cell proliferation, differentiation and migration, and monocyte/macrophage chemotaxis. In present study, we aimed to investigate the relationship between VEGF gene polymorphisms (G+405C, T-460C, and A-2578C) and PTC susceptibility.

METHODS

DNA was isolated from peripheral blood leukocytes of 127 patients with PTC and 203 healthy controls. Genotyping was performed by real-time PCR. Association of genotypes with susceptibility of PTC was analyzed with multivariate logistic regression adjusted for age, gender and smoking status.

RESULTS AND CONCLUSION

In G+405C polymorphism, the frequencies of C allele (related with increased VEGF production) and combined CG+CC genotype were found to be higher (3.5 and 5-fold, respectively) among patients with PTC than controls (P<.001). However, VEGF T-460C and A-2578C polymorphisms are not associated with PTC risk. There was no relationship between VEGF polymorphisms and clinical/laboratory parameters of PTC. Haplotype analysis demonstrated that there was a strong linkage disequilibrium (LD) between -460/-2578 (D'=.89, r² =.79), weak LD between +405/-460 (D'=.422, r² =.035), and +405/-2578 (D'=.43, r² =.038) locuses. Additionally, the +405/-460/-2578 GTA haplotype was found to be protective, whereas CTA haplotype to be related with increased PTC risk. As a conclusion, we suggest that VEGF G+405C polymorphism is associated with increased risk of PTC.

WOMEN IN CANCER THEMATIC REVIEW: Thyroid-stimulating hormone in thyroid cancer: does it matter?

Differentiated thyroid cancer is the most common endocrine malignancy and the incidence is increasing rapidly worldwide. Appropriate diagnosis and post-treatment monitoring of patients with thyroid tumours are critical. Fine needle aspiration cytology remains the gold standard for diagnosing thyroid cancer, and although there have been significant refinements to this technique, diagnostic surgery is often required for patients suspected to have malignancy. Serum thyroid-stimulating hormone (TSH) is higher in patients with malignant thyroid nodules than in those with benign disease, and TSH is proportionally increased in more aggressive tumours. Importantly, we have shown that the pre-operative serum TSH concentration independently predicts the presence of malignancy in subjects presenting with thyroid nodules. Establishing the use of TSH measurements in algorithms identifying high-risk thyroid nodules in routine clinical practice represents an exciting, cost-efficient and non-invasive approach to optimise thyroid cancer diagnosis. Binding of TSH to receptors on thyrocytes stimulates a number of growth promoting pathways both in normal and malignant thyroid cells, and TSH suppression with high doses of levothyroxine is routinely used after thyroidectomy to prevent cancer recurrence, especially in high-risk tumours. This review examines the relationship between serum TSH and thyroid cancer and reflects on the clinical potential of TSH measurements in diagnosis and disease monitoring.

Quantitative assessment of preoperative serum thyrotropin level and thyroid cancer

Thyroid stimulating hormone (TSH) is the major growth factor for thyrocytes, but the pathogenic role of serum TSH in thyroid cancer (TC) is unknown. The association between TSH level and the development of thyroid cancer has been widely evaluated recently. However, the results remain conflicting. To develop an understanding of the relationship between TSH exposure and thyroid cancer, a meta-analysis of 56 studies involving 20227 thyroid cancer cases and 50003 controls with benign thyroid nodule was performed. Overall, significantly increased TSH level was observed in thyroid cancer patients compared with controls (RoM: 1.44, 95% CI: 1.32-1.56, P < 10-5). The pooled analyses also revealed that higher serum TSH level were significantly associated with the size of TC nodule and malignancy as well as lymph node metastasis. Furthermore, significantly increased THS levels were observed preferentially for papillary thyroid cancer when stratified by histological type of tumors. However, the diagnostic value of TSH level for TC might be limited. These results suggest that higher serum TSH concentration is associated with an increased risk of thyroid cancer.

'Incidental' and 'non-incidental' thyroid papillary microcarcinomas are two different entities

OBJECTIVE

Papillary thyroid microcarcinomas (microPTC) may be 'incidental' (Inc-microPTC), occasionally found at histology after surgery for benign disease or 'non-incidental' (Non-Inc-microPTC), diagnosed on clinical grounds. It is unclear whether these different microPTC reflect the same disease. The aim of the study was to compare Inc-microPTC and Non-Inc-microPTC for clinical and histological features as well as for serum TSH, a known factor involved in PTC development.

DESIGN

We evaluated histology and serum TSH levels of consecutive patients submitted to thyroidectomy for goiter with compressive symptoms or for cytological diagnosis suspicious/indicative of PTC.

METHODS

In total, 665 consecutive patients (259 with a single thyroid nodule, SN and 406 with a multinodular gland, MN) were included in the study. According to histology, patients were classified as: benign nodular goiter (Benign, n=291); Inc-microPTC (n=92); Non-Inc-microPTC (n=67) and PTC≥1cm (macroPTC, n=215).

RESULTS

Inc-microPTC were significantly more frequent in MN than in SN (66/406, 16.2% vs 26/259, 10.0%, P=0.02). Patients with Inc-microPTC compared with Non-Inc-microPTC were older (mean age±s.d. 53.3±13.2 years vs 44.9±14.8 years, P=0.0002), had a smaller tumor size (median 4mm vs 9mm, P<0.0001), a higher frequency of multifocality (70/92, 76.1% vs 35/67, 52.2% P=0.001) and lower levels of TSH (median 0.6mIU/L, IR: 0.4-1.0mIU/L vs value 1. mIU/L, IR: 0.6-1.4mIU/L vs P=0.0001).

CONCLUSION

Incidental and non-incidental papillary thyroid microcarcinomas appear to be two different entities.

Inappropriate Suppression of Thyrotropin Concentrations in Young Patients with Thyroid Nodules Including Thyroid Cancer: The Fukushima Health Management Survey

BACKGROUND

Serum thyroid hormone concentration is regulated through the hypothalamic-pituitary-thyroid axis. This study aimed to clarify the relationships between thyroid hormone regulation and ultrasonographic findings in subjects with thyroid nodules detected during thyroid ultrasound examination for the Fukushima Health Management Survey.

METHODS

As of October 31, 2014, a total of 296,253 subjects, who had been living in Fukushima Prefecture at the time of the Fukushima nuclear power plant accident and were aged ≤18 years on March 11, 2011, participated in two concurrent screening programs. In the primary screening, thyroid nodules were detected in 2241 subjects. A secondary confirmatory thyroid ultrasound examination and blood sampling for thyroid function tests were performed on 2004 subjects. The subjects were reassessed and classified into disease-free subjects (Group 1), subjects with cysts only (Group 2), subjects with nodules (Group 3), and subjects with malignancy or suspected malignancy (Group 4). Serum concentrations of free triiodothyronine (fT3), free thyroxine (fT4), thyrotropin (TSH), thyroglobulin, and the fT3/fT4 ratio were classified according to the diagnoses.

RESULTS

Inverse relationships between age and log TSH values (Spearman's correlation r = -0.311, p = 0.015), serum fT3 concentration (r = -0.688, p < 0.001), and the fT3/fT4 ratio (r = -0.520, p < 0.001) were observed in Group 1. When analysis of covariance with Bonferroni post hoc comparisons was used in the four groups, the log TSH values were significantly lower in both Group 3 and Group 4 compared with Group 1 and Group 2 after correcting for age (p < 0.001; Group 1 vs. Group 3, p = 0.016; Group 1 vs. Group 4, p = 0.022; Group 2 vs. Group 3, p = 0.001; Group 2 vs. Group 4, p = 0.008). However, no significant differences were observed between the four groups regarding levels of fT3, fT4, fT3/fT4 ratio, and thyroglobulin (p = 0.304, 0.340, 0.208, and 0.583, respectively).

CONCLUSION

TSH suppression can be present in response to illness, including thyroid nodules, in young subjects. Low TSH levels may be associated with the finding of papillary thyroid cancer as well as with thyroid nodules in children and adolescents.

The Usefulness of Preoperative Thyroid-Stimulating Hormone for Predicting Differentiated Thyroid Microcarcinoma

OBJECTIVE

Thyroid-stimulating hormone (TSH) is a known thyroid growth factor, but the pathogenic role of TSH in thyroid tumorigenesis is controversial. The aim of this study is to examine the relationship between preoperative TSH and differentiated thyroid microcarcinoma (DTMC).

DATA SOURCES

We searched PubMed, EMBASE, Ovid, Web of Science, and the Cochrane Library from their inception to March 2015 and performed a systematic literature review of original studies.

REVIEW METHODS

Published studies that explored the relationship between preoperative TSH and DTMC were included for the review. We calculated odds ratio referring to different TSH concentrations between DTMC and control groups and used random effects model for the meta-analysis.

RESULTS

Nine eligible studies that included 6523 patients were identified. Meta-analysis revealed that DTMC was associated with high TSH concentration (odds ratio = 1.23, 95% confidence interval = 1.03-1.46, P = .001). Metaregression analysis indicated that the disparity of control groups was the possible factor resulting in heterogeneity among the studies.

CONCLUSIONS

The risk of DTMC increases significantly in parallel with TSH concentration. These results support the hypothesis that TSH is involved in tumorgenesis of differentiated thyroid cancer.