Comparative analysis of the new guidelines and consensuses for the management of hypothyroidism, thyroid nodules, and differentiated thyroid cancer

233

Thyroid nodules and differentiated thyroid cancer: update on the Brazilian consensus

Thyroid nodules are frequent findings, especially when sensitive imaging methods are used. Although thyroid cancer is relatively rare, its incidence is increasing, particularly in terms of small tumors, which have an uncertain clinical relevance. Most patients with differentiated thyroid cancer exhibit satisfactory clinical outcomes when treatment is appropriate, and their mortality rate is similar to that of the overall population. However, relapse occurs in a considerable fraction of these patients, and some patients stop responding to conventional treatment and eventually die from their disease. Therefore, the challenge is how to identify the individuals who require more aggressive disease management while sparing the majority of patients from unnecessary treatments and procedures. We have updated the Brazilian Consensus that was published in 2007, emphasizing the diagnostic and therapeutic advances that the participants, representing several Brazilian university centers, consider most relevant in clinical practice. The formulation of the present guidelines was based on the participants' experience and a review of the relevant literature.

Expression of SMAD proteins, TGF-beta/activin signaling mediators, in human thyroid tissues

OBJECTIVE: To investigate the expression of SMAD proteins in human thyroid tissues since the inactivation of TGF-β/activin signaling components is reported in several types of cancer. Phosphorylated SMAD 2 and SMAD3 (pSMAD2/3) associated with the SMAD4 induce the signal transduction generated by TGF-β and activin, while SMAD7 inhibits this intracellular signaling. Although TGF-β and activin exert antiproliferative roles in thyroid follicular cells, thyroid tumors express high levels of these proteins. MATERIALS AND METHODS: The protein expression of SMADs was evaluated in multinodular goiter, follicular adenoma, papillary and follicular carcinomas by immunohistochemistry. RESULTS: The expression of pSMAD2/3, SMAD4 and SMAD7 was observed in both benign and malignant thyroid tumors. Although pSMAD2/3, SMAD4 and SMAD7 exhibited high cytoplasmic staining in carcinomas, the nuclear staining of pSMAD2/3 was not different between benign and malignant lesions. CONCLUSIONS: The finding of SMADs expression in thyroid cells and the presence of pSMAD2/3 and SMAD4 proteins in the nucleus of tumor cells indicates propagation of TGF-β/activin signaling. However, the high expression of the inhibitory SMAD7, mostly in malignant tumors, could contribute to the attenuation of the SMADs antiproliferative signaling in thyroid carcinomas.

Hypothyroidism decreases proinsulin gene expression and the attachment of its mRNA and eEF1A protein to the actin cytoskeleton of INS-1E cells

The actions of thyroid hormone (TH) on pancreatic beta cells have not been thoroughly explored, with current knowledge being limited to the modulation of insulin secretion in response to glucose, and beta cell viability by regulation of pro-mitotic and pro-apoptotic factors. Therefore, the effects of TH on proinsulin gene expression are not known. This led us to measure: a) proinsulin mRNA expression, b) proinsulin transcripts and eEF1A protein binding to the actin cytoskeleton, c) actin cytoskeleton arrangement, and d) proinsulin mRNA poly(A) tail length modulation in INS-1E cells cultured in different media containing: i) normal fetal bovine serum - FBS (control); ii) normal FBS plus 1 µM or 10 nM T3, for 12 h, and iii) FBS depleted of TH for 24 h (Tx). A decrease in proinsulin mRNA content and attachment to the cytoskeleton were observed in hypothyroid (Tx) beta cells. The amount of eEF1A protein anchored to the cytoskeleton was also reduced in hypothyroidism, and it is worth mentioning that eEF1A is essential to attach transcripts to the cytoskeleton, which might modulate their stability and rate of translation. Proinsulin poly(A) tail length and cytoskeleton arrangement remained unchanged in hypothyroidism. T3 treatment of control cells for 12 h did not induce any changes in the parameters studied. The data indicate that TH is important for proinsulin mRNA expression and translation, since its total amount and attachment to the cytoskeleton are decreased in hypothyroid beta cells, providing evidence that effects of TH on carbohydrate metabolism also include the control of proinsulin gene expression.

Aerobic and anaerobic metabolism for the zebrafish, Danio rerio, reared under normoxic and hypoxic conditions and exposed to acute hypoxia during development

In order to verify the influence of chronic and acute ambient oxygen levels from egg to adult stage of the zebrafish, in vivo oxygen consumption (MO2), critical tensions of oxygen (Pcrit), heart rate (fH) and total body lactate concentration (Lc) were determined for Danio rerio (Hamilton, 1822) raised at 28 °C under normoxic (7.5 mgO2.L-1 or 80 mm.Hg-1) and hypoxic conditions (4.3 mgO2.L-1) and exposed to acute hypoxia during different developmental stages. Our findings confirmed that very early stages do not respond effectively to ambient acute hypoxia. However, after the stage corresponding to the age of 30 days, D. rerio was able to respond to acute hypoxia through effective physiological mechanisms involving aerobic and anaerobic metabolism. Such responses were more efficient for the fishes reared under hypoxia which showed that D. rerio survival capability increased during acclimation to mild hypoxia. Measurements of body mass and length showed that moderate hypoxia did not affect growth significantly until the fish reached the stage of 60 days. Moreover, a growth delay was verified for the hypoxic-reared animals. Also, the D. rerio eggs-to-larvae survival varied from 87.7 to 62.4% in animals reared under normoxia and mild hypoxia, respectively. However, the surviving animals raised under moderated hypoxia showed a better aptitude to regulate aerobic and anaerobic capacities when exposed to acute hypoxia.

Influence of food components on lipid metabolism: scenarios and perspective on the control and prevention of dyslipidemias

Cardiovascular diseases (CVD) are the main causes of death in the Western world. Among the risk factors that are modifiable by diet, for reducing cardiovascular disease risks, the total plasma concentrations of cholesterol, triglycerides, LDL-C, and HDL-C are the most important. Dietary measures can balance these components of the lipid profile thus reducing the risk of cardiovascular diseases. The main food components that affect the lipid profile and can be modified by diet are the saturated and trans fats, unsaturated fats, cholesterol, phytosterols, plant protein, and soluble fiber. A wealth of evidence suggests that saturated and trans fats and cholesterol in the diet raise the total plasma cholesterol and LDL-C. Trans fats also reduce HDL-C, an important lipoprotein for mediating the reverse cholesterol transport. On the other hand, phytosterols, plant proteins, isoflavones, and soluble fiber are protective diet factors against cardiovascular diseases by modulating plasma lipoprotein levels. These food components at certain concentrations are able to reduce the total cholesterol, TG, and LDL-C and raise the plasma levels of HDL-C. Therefore, diet is an important tool for the prevention and control of cardiovascular diseases, and should be taken into account as a whole, i.e., not only the food components that modulate plasma concentrations of lipoproteins, but also the diet content of macro nutrients and micronutrients should be considered.

Effects of trans-10, cis-12 conjugated linoleic acid on gene expression and lipid metabolism of adipose tissue of growing pigs

The objective of the present study was to determine the effects of trans-10, cis-12 conjugated linoleic acid (CLA) in adipose tissue explant cultures of growing pigs on the following responses: lipogenesis (measured as rate of C-14-labeled glucose incorporation over a subsequent 2-h incubation in the presence or absence of insulin), lipolysis (release of non-esterified fatty acid over a 2-h incubation in the presence or absence of isoproterenol), activities of lipogenic enzymes, and mRNA abundance of fatty acid synthase (FAS). Adipose tissue explants from nine growing pigs (78 +/- 3 kg) were cultured in 199 medium with insulin, dexamethasone and antibiotics for 4, 12, 24, and 48 h. The treatments were 1) control: 100 mu M polyvinyl alcohol (PVA); 2) pGH: 100 ng/mL porcine growth hormone (pGH) plus 100 mu M PVA; 3) CLA200: 200 mu M trans-10, cis-12 CLA; 4) CLA50: 50 mu M trans-10, cis-12 CLA, and 5) LA: 200 mu M linoleic acid. Fatty acids were added along with PVA (2: 1), respectively, for 24 h. Explants were collected after each culture period and assayed for lipogenesis. Transcripts of FAS mRNA were quantified by real-time RT-PCR after 24 and 48 h. Lipolysis and activities of FAS, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and NADP-malate dehydrogenase were determined after 48 h. As expected, glucose incorporation was decreased (P < 0.05) in response to pGH treatment (positive control). LA had no effect on any parameter evaluated. Treatment with trans-10, cis-12 CLA decreased FAS activity (P < 0.05), but NADPH-generating enzymes were unaffected by treatments. Consistent with reduction in FAS activity, both lipid synthesis and FAS mRNA abundance were reduced with chronic CLA treatment, pGH increased baseline and stimulated lipolysis (P < 0.05) after 48 h of culture, while CLA treatment had no effect on non-esterified fatty acid release. Results of this study showed that trans-10, cis-12 CLA alters lipogenesis but has no effect on lipolysis in cultures of pig adipose tissue.

Etiology of congenital hypothyroidism using thyroglobulin and ultrasound combination

Methods currently employed to establish the etiology of congenital hypothyroidism include thyroid ultrasound and scintigraphic exams. Thyroglobulin is a protein almost exclusively secreted by thyroid tissue and indirectly reflects the amount of follicular cells. Even though thyroglobulin is easy to measure, it has been not frequently used because of discordant results to distinguish mainly athyreosis and ectopy (dysgenesis). Knowing the differences in inheritance and prognosis of thyroid dysgenesis and dyshormonogenesis, it is important to define the etiology of CH, combining tools that are easy, fast and available in most medical centers. Our objective was to evaluate and compare color Doppler ultrasound and serum thyroglobulin with radionuclide scan to define the etiology of congenital hypothyroidism. We evaluated 38 children above 3 years-old off-treatment that performed serum thyroglobulin by immunofluorometric assay, color Doppler ultrasound and radionuclide study. On color Doppler ultrasound, 11 patients had athyreosis, 5 ectopic glands, being I associated to hemiagenesis. Twenty one had topic thyroid (3 goiters, 10 normal, 8 hypoplastic). Hemiagenesis and cystic lesion were not revealed by radionuclide scan. We observed substantial agreement between color Doppler ultrasound and radionuclide scan (kappa=0.745, p<0.0001). Serum thyroglobulin in athyreosis ranged from <1.0 to 18.7 mu g/L. Patients with ectopic glands showed wider thyroglobulin range (4.5 to 123 mu g/L, median 28.4 mu g/L). Only one patient showed thyroglobulin deficiency. By using color Doppler ultrasound and serum thyroglobulin levels as valuable combined tools, we established the etiology of congenital hypothyroidism limiting excessive and harmful exams in children, like radionuclide scan.

Factitious thyrotoxicosis induced by mesotherapy: A case report

Context: Mesotherapy consists of cutaneous injections of a mixture of compounds and has recently been used for cosmetic purposes to reduce local fat and cellulite. To date, several reports have described only local adverse events related to this therapy. We describe the first report of a female patient who developed thyrotoxicosis due to cosmetic mesotherapy with triiodothyroacetic acid in its formulation. Apart from mechanical rupture of the epidermal barrier, a disturbance of type III deiodinase activity or skin fibroblast paracrine function and vascular alterations related to simultaneously injected vasoactive compounds were observed. These findings could be related to thyroid hormone metabolite absorption and systemic consequences in the reported case. Conclusion: We describe factitious thyrotoxicosis induced by mesotherapy, to raise awareness of a systemic adverse effect resulting from this widespread cosmetic practice.

High Prevalence of Side Effects After Recombinant Human Thyrotropin-Stimulated Radioiodine Treatment with 30 mCi in Patients with Multinodular Goiter and Subclinical/Clinical Hyperthyroidism

Background: Treatment of multinodular goiters (MNGs) is highly controversial. Radioiodine (RAI) therapy is a nonsurgical alternative for the elderly who decline surgery. Recently, recombinant human thyrotropin (rhTSH) has been used to augment RAI uptake and distribution. In this study, we determined the outcome of 30 mCi RAI preceded by rhTSH (0.1 mg) in euthyroid (EU) and hyperthyroid (subclinical/clinical) patients with large MNGs. Methods: This was a prospective cohort study. Forty-two patients (age, 43-80 years) with MNGs were treated with 30 mCi RAI after stimulation with 0.1 mg of rhTSH. Patients were divided into three groups, according to thyroid function: EU (n = 18), subclinically hyperthyroid (SC-H, n = 18), and clinically hyperthyroid (C-H, n = 6). All patients underwent a 90-day low-iodine diet before treatment, and those with clinical hyperthyroidism received methimazole 10 mg daily for 30 days. Serum TSH, free thyroxine (FT4), total triiodothyronine (TT3), and thyroglobulin were measured at baseline and at 24, 48, 72, 168 hours, and 1, 3, 6, 9, 12, 18, 24, and 36 months after therapy. Thyroid volume was assessed by computed tomography at baseline and every 6 months. Results: Patients had high iodine urinary excretion (308 +/- 108 mu g I/L) at baseline. TSH levels at baseline were within the normal range (1.5 +/- 0.7 mu U/mL) in the EU group and suppressed (< 0.3 mu U/mL) in the SC-H and C-H groups. After rhTSH, serum TSH peaked at 24 hours reaching 12.4 +/- 5.85 mu U/mL. After RAI administration, patients in both hyperthyroid groups had a higher increase in FT4 and TT3 compared with those in the EU group (p < 0.001). Thyroglobulin levels increased equally in all three groups until day 7. Thyroid volume decreased significantly in all patients. Side effects were more common in the SC-H and C-H groups (31.4% and 60.4%, respectively) compared with EU patients (17.8%). Permanent hypothyroidism was more prevalent in the EU group (50%) compared with the SC-H (11%) and C-H (16.6%) groups. Conclusions: Patients with MNG may have subclinical and clinical nonautoimmune iodine-induced hyperthyroidism. Despite a low-iodine diet and therapy with methimazole, hyperthyroid patients have a significantly higher increase in FT4 and TT3 levels after RAI ablation. This can lead to important side effects related mostly to the cardiac system. We strongly advise that patients with SC-H and C-H be adequately treated with methimazole and low-iodine diet aiming to normalize their hyperthyroid condition before rhTSH-stimulated treatment with RAI.

Phenotypic variation among four family members with congenital hypothyroidism caused by two distinct thyroglobulin gene mutations

Background: Thyroglobulin (Tg) is a large glycoprotein that is intimately involved in the biosynthesis of thyroxine and triiodothyronine. At least 38 mutations have been described in the Tg gene that are associated with varying degrees of hypothyroidism. We studied the Tg gene in four related subjects with congenital hypothyroidism. Summary: We found a novel compound heterozygous constellation (IVS30 + 1G>T/A2215D) in a brother and sister and one previously described related mutation (IVS30+1G>T) in their two sibling second degree cousins. The brother with the IVS30 + 1G>T/A2215D mutation and the two siblings with the IVS30+1G>T mutation had fetal or neonatal goiter and all had hypothyroidism. Conclusions: This study further confirms the association of the IVS30+1G>T mutation of the Tg gene with hypothyroidism. Computer analysis predicts that the A2215D mutation, first reported here, should cause structural instability of Tg but when present as a compound heterozygous mutation with IVS30+G>T/A its effect is unclear but is likely to be influenced by iodine intake.

Proteome analysis of schizophrenia patients Wernicke's area reveals an energy metabolism dysregulation

Background: Schizophrenia is likely to be a consequence of DNA alterations that, together with environmental factors, will lead to protein expression differences and the ultimate establishment of the illness. The superior temporal gyrus is implicated in schizophrenia and executes functions such as the processing of speech, language skills and sound processing. Methods: We performed an individual comparative proteome analysis using two-dimensional gel electrophoresis of 9 schizophrenia and 6 healthy control patients' left posterior superior temporal gyrus (Wernicke's area - BA22p) identifying by mass spectrometry several protein expression alterations that could be related to the disease. Results: Our analysis revealed 11 downregulated and 14 upregulated proteins, most of them related to energy metabolism. Whereas many of the identified proteins have been previously implicated in schizophrenia, such as fructose-bisphosphate aldolase C, creatine kinase and neuron-specific enolase, new putative disease markers were also identified such as dihydrolipoyl dehydrogenase, tropomyosin 3, breast cancer metastasis-suppressor 1, heterogeneous nuclear ribonucleoproteins C1/C2 and phosphate carrier protein, mitochondrial precursor. Besides, the differential expression of peroxiredoxin 6 (PRDX6) and glial fibrillary acidic protein (GFAP) were confirmed by western blot in schizophrenia prefrontal cortex. Conclusion: Our data supports a dysregulation of energy metabolism in schizophrenia as well as suggests new markers that may contribute to a better understanding of this complex disease.

Myocardial ultrasonic tissue characterization in patients with thyroid dysfunction

Background: Structural myocardial abnormalities have been extensively documented in hypothyroidism. Experimental studies in animal models have also shown involvement of thyroid hormones in gene expression of myocardial collagen. This study was planned to investigate the ability of ultrasonic tissue characterization, as evaluated by integrated backscatter (IBS), to early identify myocardial involvement in thyroid dysfunction. Patients and Methods: We studied 15 patients with hyperthyroidism (HYPER), 8 patients with hypothyroidism (HYPO), 14 patients with subclinical hypothyroidism (SCH) and 19 normal (N) subjects, who had normal LV systolic function. After treatment, 10 HYPER, 6 HYPO, and 8 SCH patients were reevaluated. IBS images were obtained and analyzed in parasternal short axis (papillary muscle level) view, at left ventricular (LV) posterior wall. The following IBS variables were analyzed: 1) the corrected coefficient (CC) of IBS, obtained by dividing IBS intensity by IBS intensity measured in a rubber phantom, using the same equipment adjustments, at the same depth; 2) cardiac cyclic variation (CV) of IBS - peak-to-peak difference between maximal and minimal values of IBS during cardiac cycle; 3) cardiac cyclic variation index (CVI) of IBS - percentual relationship between the cyclic variation (CV) and the mean value of IBS intensity. Results: CC of IBS was significantly larger (p < 0.05) in HYPER (1.57 +/- 0.6) and HYPO (1.53 +/- 0.3) as compared to SCH (1.32 +/- 0.3) or N (1.15 +/- 0.27). The CV (dB) (HYPO: 7.5 +/- 2.4; SCH: 8.2 +/- 3.1; HYPER: 8.2 +/- 2.0) and the CVI (HYPO: 35.6 +/- 19.7%; SCH: 34.7 +/- 17.5%; HYPER: 37.8 +/- 11.6%) were not significantly different in patients with thyroid dysfunction as compared to N (7.0 +/- 2.0 and 44.5 +/- 15.1%). Conclusions: CC of IBS was able to differentiate cardiac involvement in patients with overt HYPO and HYPER who had normal LV systolic function. These early myocardial structural abnormalities were partially reversed by drug therapy in HYPER group. On the other hand, although mean IBS intensity tended to be slightly larger in patients with SCH as compared to N, this difference was not statistical significant.

Hypothalamic-pituitary axis and peripheral tissue responses to TRH stimulation and Liothyronine suppression tests in normal subjects evaluated by current methods

Objective: To reevaluate the responses of thyrotropin-releasing hormone ( TRH) stimulation test in baseline condition as well as after the administration of graded supraphysiological doses of liothyronine ( L- T-3) in normal subjects. Design: To assess various parameters related to the hypothalamic-pituitary axis and peripheral tissue responses to L- T-3 in 22 normal individuals ( median age: 30.5 years). Subjects were submitted to an intravenous TRH test at baseline condition and also to the oral administration of sequential and graded doses of L- T-3 ( 50, 100, and 200 mu g/day), each given over 3 days, at an outpatient clinic. Blood samples were obtained for thyrotropin (TSH) and prolactin (PRL) at basal and then 15, 30, and 60 minutes after the TRH injection. Effects of L- T3 administration on cholesterol, creatine kinase, retinol, ferritin, and sex hormone-binding globulin ( SHBG) were also measured at basal and after the oral administration of L- T-3. Main outcome: TRH administration resulted in an increase of 4-to 14-fold rise in serum TSH ( 8.3 +/- 2.5-fold), and in a slight rise in serum PRL concentrations ( 3.8 +/- 1.5-fold). Administration of graded doses of triiodothyronine ( T-3) resulted in a dose-dependent suppression of TSH and PRL. Basal thyroxine- binding globulin (TBG) and cholesterol levels decreased, and ferritin and SHBG increased after L- T-3 administration, while creatine kinase and retinol did not change throughout the study. There was a positive correlation between basal TSH and TSH peak response to TRH at basal condition and after each sequential L- T-3 doses. On the other hand, TSH peak response to the TRH test did not predict cholesterol, TBG, ferritin, or SHBG values. Conclusion: Using the current methods on hormone and biochemical analysis, we standardized the response of many parameters to TRH stimulation test after sequential and graded T-3 suppression test in normal subjects. Our data suggest that the evaluation of the responses of the hypothalamus-pituitary axis to TRH test as well as the impact of L- T-3 on peripheral tissues were not modified by the current methods.

The role of major histocompatibility complex Alleles in the susceptibility of Brazilian patients to develop the myogenic type of Graves' orbitopathy

Objective: To assess the frequency of the genetic markers HLA-DRB1 and DQB1 in patients with Graves' orbitopathy ( GO) with and without extraocular muscle involvement. Design: The frequencies of class II HLA-DRB1 and DQB1 allele groups were determined for 81 Brazilian patients with GO and 161 normal subjects. The patients were divided into myogenic and nonmyogenic groups based on the clinical characteristics of the orbitopathy and quantitative computed tomography analysis of the extraocular muscle ( EOM) dimensions. Main outcome: Compared to the frequency obtained for samples of normal subjects of the Brazilian population, HLA-DRB1*16 (p(c)= 0.008) was overrepresented in myogenic and HLA-DRB1*03 (p(c)= 0.02) in nonmyogenic patients. Conclusions: The association between the HLA-DRB1* 16 and the myogenic subtype of GO suggests that EOM involvement in GO may be genetically predisposed.