Thyroid®

Hypothyroidism decreases energy expenditure and combustion of fuels, but the reported effects on lipid metabolism and insulin sensitivity are divergent and there is a lack of studies assessing rates of lipolysis and lipid oxidation. The present study was conducted to test the hypotheses that hypothyroidism decreases lipolysis, blood concentrations of free fatty acid, lipid oxidation, and insulin sensitivity.

We studied 11 hypothyroid patients (thyroid-stimulating hormone: 150 mU/L) with autoimmune thyroiditis (i) before and (ii) after 2 months of triiodothyronine-euthyroidism upon levothyroxine treatment and (iii) compared the patients to 10 healthy volunteers. Subjects underwent a 3-hour study in the basal state followed by a 3-hour euglycemic clamp study, and we used a combination of lipid blood concentrations, palmitate tracer dilution, and indirect calorimetry to assess lipid metabolism.

Compared to euthyroid control subjects and/or euthyroid posttreatment values hypothyroid patients were characterized by (i) 40%–50% decreased concentrations of plasma free fatty acids, palmitate, and 3-OH-butyrate (p < 0.05); (ii) >50% decreased lipid oxidation by indirect calorimetry (p < 0.001); (iii) unchanged whole-body lipolysis by palmitate dilution (all p's > 0.45); (iv) 50% increased triglyceride levels (p < 0.05); and (v) ∼30% decreased insulin sensitivity judged by glucose infusion rate values (p = 0.05).

Our data show that hypothyroidism leads to decreased concentrations and oxidation rates of lipid intermediates and increased triglyceride concentrations in the presence of unaltered rates of lipolysis. The combination of normal lipolysis, low lipid oxidation rates, and high triglyceride concentrations is compatible with increased triglyceride synthesis.

Graves' disease (GD) is caused by thyrotropin (TSH) receptor antibodies (TSHRAbs) that bind to TSHR and activate thyrocytes. The measurement of TSHRAbs therefore has been used to assist in the diagnosis and management of GD.

In this study, we evaluated the clinical significance of a newly developed bioreporter assay for the detection of TSHRAbs (Thyretain™). The Thyretain bioreporter assay utilizes a chimeric receptor (Mc4), in which residues 262–335 of TSHR are replaced with a rat lutropin-choriogonadtropin receptor segment. This bioreporter is designed to specifically detect stimulating TSHRAbs (Mc4-TSHRAbs).

The Mc4-TSHRAb level of sera obtained from 110 normal healthy controls, 103, 99, and 50 patients with untreated GD, painless Hashimoto's thyroiditis (PT), and subacute thyroiditis (SAT) were 27.3% ± 11.3%, 327.8% ± 105.9%, 48.9% ± 48.5%, and 24.9% ± 13.4%, respectively. Compared with the Mc4-TSHRAb levels of patients with PT and SAT, and normal healthy controls, the Mc4-TSHRAb levels of untreated GD patients were significantly higher (p < 0.01). The sensitivity and specificity of the Thyretain bioreporter assay for GD and PT were 95.1% and 96.0%, respectively, at the optimal cut-off value of 128%. Measurement of TSHRAbs with a bioassay that uses porcine thyroid cells (TSH-stimulating antibody [TSAb]) showed a positive correlation (r = 0.472, p < 0.001) with the Thyretain assay for untreated GD, and strong positive correlation (r = 0.821, p < 0.001) for the entire untreated GD, PT, and SAT population. The positive rate of Mc4-TSHRAbs for GD was significantly higher than that of TSAb (95.1% vs. 89.3%, p < 0.05) and the negative rate of PT by Mc4-TSHRAbs was also significantly higher than that of TSAb (96.0% vs. 86.9%, p < 0.01). As a result, Mc4-TSHRAbs showed statistically better (p < 0.01) diagnostic accuracy in differentiating GD from PT than TSAb.

These data suggest that the Thyretain bioreporter assay with a chimeric TSHR (Mc4) is more useful in the differential diagnosis of GD from PT than the bioassay with wild-type TSHR on porcine thyroid cells.

Benign-appearing cervical lymph nodes (CLN) are easy to assess during an ultrasonography (US) evaluation for a guided fine-needle aspiration biopsy of a suspicious thyroid nodule, but their clinical significance regarding thyroid cancer risk is not known. Non-malignant-appearing nodes may be an indicator of early malignancy in the thyroid. We hypothesize that there is an increased prediction of thyroid cancer when benign-appearing enlarged CLN (ECLN) > 1 cm in any dimension are present during an US evaluation of thyroid nodules.

A review of 269 consecutive patients' charts sent for thyroid nodule assessment that underwent thyroidectomy was conducted to compare ECLN, with the presence of thyroid cancer during an ultrasound-guided fine-needle aspiration biopsy of the thyroid nodule. Surgical excision pathology confirmed all abnormal cytology reports.

From the final 265 charts reviewed, 213 had benign thyroid pathology and 52 had thyroid cancer. Sex, number, and size of the biggest thyroid nodule were not different between groups. Patients with cancer were on average 10 years younger and had higher thyroid-stimulating hormone (TSH) values (p < 0.003) as well as a 10-fold increase in enlarged non-malignant-appearing lymph nodes than their peers without cancer. The presence of ECLN had an 82% sensitivity, 90% specificity, and a 68% positive predictive value for thyroid cancer. There was also an 80% negative predictive value when enlarged lymph nodes were not present. In 8 of the 37 (21.6%) patients with malignancy and ECLN, the primary dominant thyroid nodule was negative on cytologic evaluation, but malignancies were confirmed on surgical specimen, in contralateral nodules on the same side as the ECLN. These nodules were mostly subcentimeric, ranging from 0.2 to 1.14 cm and were not biopsied due to their inconspicuous appearance. After multiple logistic regression analysis, enlarged lymph nodes had a 53.8 odds ratio for cancer (20.49–141.33, p < 0.01).

Discovering the presence of ECLN in routine assessment of thyroid nodules is an easy and fast surveillance technique that increases the predictive value in diagnosing thyroid cancer, especially when the enlarged lymph nodes are on the same side as the thyroid nodule.

Vascular endothelial growth factor (VEGF-A) expression is upregulated in the majority of human tumors, where it stimulates proliferation, migration, and survival of endothelial cells. Studies have suggested that VEGF inhibitors can be used as an alternative therapy in medullary thyroid carcinoma (MTC), but data about expression of VEGF-A and its receptor in this tumor are scarce. The aims of this study were to evaluate VEGF-A, VEGF receptor (VEGFR)-1, VEGFR-2, and microvessel density (MVD) expression in MTC samples and correlate it with clinical parameters.

Paraffin-embedded samples from 38 MTC patients were evaluated for VEGF-A, VEGFR-1, VEGFR-2, and MVD expression by immunohistochemistry. Clinical data were retrospectively reviewed in medical records.

Thirty-eight patients aged 31.8 ± 17.1 years were enrolled. Twenty-seven patients had hereditary disease (71.1%). Twenty-five of them were found to have multiple endocrine neoplasia (MEN) 2A and two were found to have MEN 2B. VEGF-A immunohistochemical staining was detected in 95% (36/38), VEGFR-1 in 96% (36/37), and VEGFR-2 in 91% (31/34) of MTC samples. Age at surgery was positively correlated with VEGFR-2 (p = 0.003). There was no correlation between VEGF-A, VEGFR-2, and tumor stage (tumor node metastasis). Nevertheless, VEGFR-1 was found to be inversely correlated with tumor node metastasis (p = 0.034). We also observed a trend toward an association between VEGFR-1 signal intensity and cure of disease, although this did not reach statistical significance (p = 0.054). Neither VEGF-A nor VEGFR-2 was associated with disease outcome after a median follow-up period of 5 years (p = 0.882 and p = 0.236, respectively). As expected, MVD was correlated with age at surgery (p = 0.005) and tumor size (p = 0.03). Patients with the hereditary form of the disease had a stronger intensity for VEGFR-1 (p = 0.039), whereas patients with sporadic disease displayed higher MVD counts (44 [27–63] vs. 21 [9–49], p = 0.018).

The VEGF-A, VEGFR-1, and VEGFR-2 immunoreactive proteins are overexpressed in MTC lesions and might be implicated in tumor progression. It is not clear, however, if expression of these molecules provides prognostic information regarding the spread or outcome of MTC.

Some but not all reports, particularly those of a retrospective nature, have noted an increased risk of carcinoma in thyroid nodules in patients with Hashimoto's thyroiditis (HT). Thyroid cancer (TC) in patients with HT, however, have been reported to have a better prognosis. In the presence of HT, the ultrasonography (US) appearance of the thyroid gland might vary greatly, making it more difficult to differentiate between benign and malignant nodules. The aim of this study was to determine if there is an association between TC and HT and to determine if the US and histopathologic characteristics of malignant nodules in patients with and without HT are similar.

Six hundred thirteen patients who underwent total thyroidectomy between 2005 and 2008 for nodular goiter were included in this study. The preoperative US characteristics and postoperative histopathologic features in patients with and without HT were compared. The diagnosis of HT was based on histopathologic features.

Ninety-two patients had HT. The prevalence of TC in the HT patients was 45.7%. In contrast, it was 29% in patients without HT (p = 0.001). The prevalence of HT in the patients with TC was 21.8% and in patients without TC was 11.9% (p = 0.001). The rate of incidental TC, defined as TC identified during surgery or following histopathologic examination of permanent sections despite preoperative benign cytology results, was higher in patients with HT (33.3%) than in those without (13.0%) HT (p = 0.004). The US characteristics of papillary thyroid carcinoma, which included number of nodules, echogenity, echoic texture, microcalcifications, macrocalcifications, halo sign, and regularity of margins, were similar in the group with HT compared with the group without HT. When the histopathologic characteristics of papillary thyroid carcinoma in patients with and without HT were compared, again there was no significant difference.

We suggest that there is an association between HT and TC, and HT may predispose to the development of TC. This indicates the need for close observation of neoplastic changes in patients with HT. Nevertheless, the presence of HT seems to have no effect on the US and histopathologic characteristics of malignant nodules in TC patients. This finding may indicate that evaluation of nodules and initial treatment of TC in these patients does not require different management.

¹²⁴I emits a positron and can be imaged with a positron emission tomography (PET) scanner. The objective of this study was to compare the ability of diagnostic ¹²⁴I PET images versus ¹³¹I planar whole-body imaging in detecting residual thyroid tissue and/or metastatic well-differentiated thyroid cancer (WDTC).

Patients were recruited prospectively for this study who (i) had WDTC, (ii) were suspected of having metastatic WDTC, and (iii) were referred for ¹³¹I whole-body dosimetry. The prescribed activity was 1–2 mCi (37–74 MBq) and 1.7 mCi (62.9 MBq) for ¹³¹I and ¹²⁴I, respectively. For each image, one blinded reader (D.V.N.) categorized every focus of ¹³¹I and ¹²⁴I radioiodine uptake as 1 = definite physiological uptake/artifact, 2 = most likely physiological uptake/artifact, 3 = indeterminate, 4 = residual thyroid tissue/metastases in the neck/bed, 5 = most likely metastases, or 6 = definite metastases. Foci categorized as 4, 5, or 6 were considered positive. When available, foci categorized as 4, 5, or 6 were correlated with other diagnostic studies.

Of the 25 patients, 8 patients (32%) had more positive foci on ¹²⁴I images than on ¹³¹I, of which 3 patients to date have had metastases confirmed in one or more of the additional positive ¹²⁴I foci. ¹²⁴I demonstrated the same number of foci as on ¹³¹I in 16 patients (14 with no positive foci, and 2 with two positive and five positive foci each). One patient had one additional positive focus on ¹³¹I not seen on ¹²⁴I, which has not yet been confirmed as a metastasis. A total of 97 positive foci were identified on either ¹²⁴I or ¹³¹I. ¹²⁴I identified 49 positive foci not seen with ¹³¹I, and ¹³¹I identified one positive focus not seen with ¹²⁴I.

Relative to ¹³¹I planar whole-body imaging, ¹²⁴I PET identified as many as 50% more foci of radioiodine uptake suggestive of additional residual thyroid tissue and/or metastases in as many as 32% more patients who had WDTC.

The association between autoimmune thyroiditis (AIT) and thyroid cancer is still not clear despite many previous reports. This study investigated whether serologic thyroid antibodies are predictive of thyroid cancer in patients with thyroid nodules.

We retrospectively reviewed records of patients with thyroid nodules evaluated by ultrasonography-guided fine-needle aspiration cytology at our institution between January 2006 and December 2008. Thyroid autoimmunity was assessed by measuring thyroglobulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb). The final outcome deciding a benign or malignant status involved a combination of cytology and histology.

Of the 1638 patients, malignant nodules had a higher rate of positive TgAb (30.8% vs. 19.6%; p < 0.001) and elevated thyrotropin (TSH) levels (2.5 ± 2.8 mIU/L vs. 2.1 ± 2.0 mIU/L; p = 0.021) than benign nodules. The rate of positive TPOAb was not higher in malignant nodules, although both TPOAb and TgAb were well correlated with TSH levels and histological AIT. In the multivariate analysis, a positive TgAb was significantly associated with thyroid cancer (odds ratio [OR] = 1.61, 95% confidence interval [CI] 1.12–2.33) with upper tertile of normal range of TSH levels (OR = 1.72, 95% CI 1.12–2.63) and above normal range of TSH levels (OR = 1.98, 95% CI 1.06–3.70).

We report for the first time that a positive serum TgAb test was an independent predictor for thyroid malignancy in thyroid nodules along with serum TSH levels regardless of the presence of AIT. Our results suggest that TgAb measurement could give additional information for predicting malignancy in cytologically indeterminate thyroid nodules in conjunction with clinical risk factors and TSH levels.

A missence single-nucleotide polymorphism (SNP) in the protein tyrosine phosphatase nonreceptor 22 (PTPN22) gene known as R620W (rs2476601) was recently reported to be associated with several autoimmune diseases including Graves' disease (GD). The association was repeatedly confirmed in the populations of North European ancestry. However, this amino acid was reported to be nonpolymorphic in the Asian populations. Since the gene confers an impact on autoimmune diseases, we attempt to explore an association between the PTPN22 gene and autoimmune thyroid disease (AITD) in a Japanese population without restricting to rs2476601. Previous investigations have also demonstrated that two intronic SNPs (rs706778 and rs3118470) in the interleukin-2 receptor-α (IL2RA) gene were associated with type 1 diabetes in the Japanese population.

We genotyped the five SNPs (rs12760457, rs2797415, rs1310182, rs2476599, and rs3789604) of the PTPN22 and the two SNPs (rs706778 and rs3118470 in the IL2RA gene) in 456 Japanese patients with AITD (286 with GD, 170 with Hashimoto's thyroiditis) and 221 matched Japanese control subjects. Seven SNPs were analyzed by either the SNAPshot method or the high-resolution melting and unlabeled probe methods. Case-control association studies were performed using the χ ² and Fisher's exact tests with Yates correction. Haplotype was conducted using the expectation-maximization algorithm.

No association was found between any of the individual SNPs of the PTPN22 gene and AITD. Permutation analysis revealed that the distribution of one haplotype is significantly different between patients with AITD and controls (p = 0.0036). A novel protective effect of a haplotype containing five SNPs was observed (p < 0.0001 for AITD, p < 0.0001 for GD, and p < 0.0001 for Hashimoto's thyroiditis, respectively). The GG allele of rs3118470 in the IL2RA gene was significantly associated with GD (p = 0.03), although the association was weak.

Significant difference in the distribution of the haplotype suggests that the PTPN22 gene rather than rs2476601 is involved in the development of AITD in the Japanese population.

The thyroidal response of pregnant patients with established Hashimoto's thyroiditis remains poorly described. The aim of this study was to determine the impact of pregnancy on Hashimoto's thyroiditis as revealed by changes in postpregnancy levothyroxine requirements.

We performed a retrospective study of 799 hypothyroid patients in a university hospital. We reviewed the clinical records and selected a group of well-documented pregnant (n = 34) and nonpregnant (n = 32) hypothyroid women for study. We reviewed levothyroxine intake and serum thyrotropin (TSH) levels during three consecutive 9-month time intervals that were immediately before, during, and after pregnancy. We compared the percent change in levothyroxine dose between the prepregnancy level and each trimester during and after pregnancy.

There were two patterns of levothyroxine supplementation during gestation. In pattern 1 (n = 11) there was either no change or a single levothyroxine dose increase with no subsequent changes in each trimester (T1 = T2 = T3). In pattern 2 (n = 18), multistep levothyroxine dose increases were required throughout pregnancy (T1 < T2 < T3) to maintain desired TSH levels (<2.0 mU/L). Women with pattern 2 had mean TSH levels during gestation that differed significantly from pattern 1 (2.8 ± 0.5 vs. 1.3 ± 0.1 mU/L respectively; p < 0.03). Further, in multivariate logistic regression, women with pattern 2 were 62 times more likely than women with pattern 1 to have a levothyroxine dose at least 20% above baseline at 3 months postpartum (p = 0.04).

We showed that >50% of hypothyroid women with Hashimoto's thyroiditis experienced an increase in levothyroxine requirements in the postpartum compared to pregestational doses. This pattern of enhanced levothyroxine need was most likely dependent on the preexisting thyroid functional reserve and postpartum progression of autoimmune destruction.

Maternal thyroid hormones (THs), especially thyroxine (T₄), are crucial to early brain development in the mammalian embryo. Epidemiological studies and case reports have shown that maternal subclinical hypothyroidism may result in significant negative effects on pregnancy and neurodevelopment of the fetus. To understand the mechanism responsible for these neurological alterations, we induced maternal subclinical hypothyroidism in pregnant rats. Behavior and several genes that are under the control of THs were evaluated in the offspring of TH-deficient rats.

A total of 60 female rats were divided into three groups: (i) maternal subclinical hypothyroidism (total thyroidectomy with T₄ infusion), (ii) maternal hypothyroidism (total thyroidectomy without T₄ infusion), and (iii) control (sham operated). All rats were mated 10 days after the start of infusion. The infusion continued until 10 days postpartum. Pups were sacrificed at postnatal day 3 (PND 3), PND 7, and PND 21. The hippocampus was collected and tested for brain-derived neurotrophic factor (BDNF) and Rap1 protein expression by Western blotting and for BDNF and neural cell adhesion molecule mRNA expression by real-time polymerase chain reaction. On PND 41–PND 49, rat pups explored the Morris water maze. Time spent in the quadrant previously containing the platform was recorded.

This study found decreases in BDNF mRNA expression (on PND 3) and protein level (on PND 3 and PND 7) in hippocampi of pups from subclinical hypothyroidism dams (p < 0.05). Rap1 protein expression was higher in maternal subclinical hypothyroidism offspring than in control offspring at PND 7 and PND 21. No change was observed in neural cell adhesion molecule mRNA expression in the maternal subclinical hypothyroidism offspring. In addition, results from the Morris water maze revealed that pups from the subclinical hypothyroidism dams showed deficits in long-term memory, spending less time in the platform quadrant (p < 0.05) during testing. There was a trend toward a deficit in short-term memory (p > 0.05) in this group as well.

The long-term memory deficits of pups born to maternal subclinical hypothyroidism dams likely related with decreasing in BDNF mRNA expression and protein level as well as increasing in Rap1 protein expression in hippocampi.

We describe a rare case of congenital hypothyroidism and an extremely high serum thyrotropin (TSH) level caused by a combination of resistance to thyroid hormone (RTH) and a lingual thyroid. As the RTH mutant, R316C, was new, the optimum dose of levothyroxine was unclear. To aid in assessment of the therapy, we characterized the mutant R316C thyroid hormone receptor (TR) and compared it with a common mutant, R316H, using in vitro studies.

The patient was a newborn female having severe hypothyroidism with a free thyroxine level of 0.36 ng/dL and a serum TSH level of 177 μU/mL. A scintiscan showed ectopic lingual thyroid tissue without a normal thyroid gland. Supplementation with levothyroxine at a dose of >350 μg/day did not normalize the serum TSH level; however, the patient showed normal growth and intelligence at 14 years of age. Consistent with the results of a computer analysis, the binding of R316C to triiodothyronine (T3) was significantly decreased to 38% that of the wild type. Electrophoretic mobility shift assay demonstrated that like R316H, R316C did not form a homodimer, but formed a heterodimer with RXR. However, a glutathione-S-transferase pull-down assay showed reduced binding of R316C with NCoR in the absence of T3 and impaired release in the presence of T3. In addition, transient transfection experiments demonstrated that unlike R316H, R316C had severe impairment of transcriptional activity on genes both positively and negatively regulated by thyroid hormone. It also had a clear dominant negative effect on genes negatively, but not positively, regulated by thyroid hormone, including the TSH-releasing hormone and TSHβ genes.

This is the first reported case of a R316C TR mutation. The characteristics of the R316C mutant differed from those of the R316H mutant. Our findings suggest that R316C causes reduced association with and impaired release of NCoR, resulting in RTH predominantly at the pituitary level, and that slightly elevated serum TSH level with high dose of levothyroxine might be optimum for normal growth.