Determinants of thyroid volume as measured by ultrasonography in healthy adults randomly selected

Ultrasound characteristics of normal parathyroid glands and analysis of the factors affecting their display

BACKGROUND

Parathyroid glands are important endocrine glands, and the identification of normal parathyroid glands is crucial for their protection. The aim of this study is to explore the sonographic characteristics of normal parathyroid glands and analyze the factors affecting their display.

METHODS

Seven hundred three subjects who underwent physical examination at our hospital were included. The number, location, size, morphology, echogenicity and blood flow distribution of parathyroid glands were recorded. The ultrasound characteristics and display rate were also summarized. Meanwhile, shear wave elastography was performed in 50 cases to provide the stiffness measurements, and 26 cases received contrast-enhanced ultrasonography for the assessment of microcirculatory perfusion. Furthermore, we analyzed the factors affecting parathyroid display, including basic information of the subjects and ultrasound features of the thyroid.

RESULTS

① A total of 1038 parathyroid glands were detected, among which, 79.29% were hyperechoic, 20.71% were isoechoic, 88.15% were oval-shaped, and 86.71% had blood flow of grade 0-I. ② 81.79% of the subjects had at least one parathyroid gland detected. ③ The Emean, Emax, PI and AUC of the parathyroid glands were significantly lower than those of the adjacent thyroid tissue (P < 0.05). ④ The display of normal parathyroid glands was related to BMI, thyroid echogenicity and thyroid volume of the subjects (P < 0.05).

CONCLUSIONS

Normal parathyroid glands tend to appear as oval-shaped hyperechoic nodules with blood flow of grade 0-I. BMI, thyroid echogenicity and thyroid volume are independent factors affecting the display of parathyroid glands.

[Normal values for adult thyroid volume on ultrasound - where do they come from and how should they be evaluated?]

The upper limit for the thyroid volume is 18 ml for women and 25 ml for men. These reference values are used and taught in many clinics and practices across several disciplines. The thyroid volume is a relevant factor for the treatment course. But where do the standard values for thyroid volumes come from, what kind of studies have been carried out to establish them? Should these upper limits be used as an universal standard in clinical routine, and which factors can influence the physiological organ size? The following article is dedicated to a critical review of the commonly used reference values for the thyroid volume of adults.

The relationship between maternal thyroid volume, TSH levels, and Healthy Eating Index scores in BMI-matched pregnant women with hyperemesis gravidarum

OBJECTIVE

The aim is to investigate the relationship between thyroid volume measurement and healthy nutrition questionnaire scoring in pregnant women diagnosed with hyperemesis gravidarum (HEG).

METHODS

One hundred and fifty pregnant women with a BMI of 15-25 kg/m² and between the ages of 17 and 42 who were diagnosed with HEG at 11-14 weeks of gestation were included in the study. Patients with a history of any disease, drug use, and previously diagnosed eating disorders were excluded. All patients were subjected to the Healthy Eating Index (HEI) questionnaire. The cutoff value for HEI score was determined as 80 points. Patients were evaluated in two groups: group 1 (HEI <80 score) and group 2 (HEI ≥80 score). Complete urine analysis including ketonuria, and thyroid function tests including TSH, T3, and T4 levels were performed for all patients. In addition, the thyroid gland volume of every patient was measured by the same radiologist.

RESULTS

Increased thyroid gland volume was significantly associated with lower TSH levels (p = .02) and lower HEI scores (p < .001). On the other hand, it was not significantly associated with ketonuria (p = .47), and parity status (p = .82).

CONCLUSIONS

In our study, we found that there may be an increase in thyroid volume in pregnant women with HEG with lower TSH levels and eating scores. Thyroid volume may predict the patients with probable eating disorders and further studies on thyroid volume in patients with HEG may contribute to the literature.

Risk factors for hypothyroidism following hemithyroidectomy

OBJECTIVE

Hypothyroidism is the most common complication of hemithyroidectomy for thyroid nodules. This retrospective cohort study investigated the prognostic factors for hypothyroidism following hemithyroidectomy.

METHODS

We included patients who underwent hemithyroidectomy between 2016 and 2017, excluding those with history of preoperative hypothyroidism or malignancy on histopathological examination. The primary endpoint was development of hypothyroidism during follow-up (TSH≥2 above normal).

RESULTS

Twenty-six of the 128 included patients (20%) developed postoperative hypothyroidism. The following independent prognostic factors were found: preoperative TSH level>1.5 mIU/L (OR 2.11; P=0.013), and remaining thyroid volume adjusted for body surface area<4.0mL/m2 (OR 1.77; P=0.015). Twenty-one patients (81%) had first TSH values above the upper limit of normal. Postoperatively, first TSH level correlated significantly with the preoperative value (R=0.5779, P<0.001). Levothyroxine was prescribed to 16% of patients, with a mean dose of 0.92μg/kg/day.

CONCLUSION

Patients with TSH>1.5 mIU/or remaining thyroid volume adjusted for body surface area<4.0mL/m2 should have intensified clinical and biological follow-up in the first year after surgery.

Influencing Factors and New Reference Intervals of Adult Thyroid Volume in Iodine-Sufficient Areas of China

The diagnosis of goiter is based on the thyroid volume measured by ultrasound in which iodine plays an important role. The purpose of this study was to evaluate the factors that affect thyroid volume and update the reference range of thyroid volume to provide a new basis for the diagnosis and treatment of goiter. A study population from mainland China was evaluated in the Thyroid disorders, Iodine status and Diabetes Epidemiological (TIDE) study. Thyroid size was measured by ultrasound, and thyroid volume was calculated. A quantile regression model was used to analyze the influence of related factors on the thyroid volume at each percentile. The median urinary iodine concentration (UIC) was 185.54 μg/l. The quantile regression model suggested that body surface area (BSA) and thyroid-stimulating hormone (TSH) were positive and negative factors for thyroid volume, respectively (p < 0.01). Excess iodine reduces the median and lower limits of thyroid volume. In iodine-sufficient areas, smoking is no longer a risk factor. The reference value range of thyroid volume stratified by sex was 3.92-19.06 ml for males and 3.1-16.17 ml for females. The maximum reference ranges for stratification by sex and BSA were 4.25-20.98 ml for men and 3.44-18.31 ml for women. The iodine nutrition level of the population in mainland China is sufficient. Iodine has the potential to alter the effect of certain factors on thyroid volume and effect is not regional. The new reference interval of adult thyroid volume based on sex and BSA has been updated, which can be used as a reliable reference for updating the diagnostic criteria of endemic goiter.

Normal thyroid volume in subjects evaluated in a primary ambulatory setting in Liguria

BACKGROUND

Ultrasonography (US) is the simplest method of evaluating thyroid volume (TV). The current normal TV in Liguria is not known. The aim of this study was to obtain normative data on TV in Liguria, Italy.

METHODS

From 3552 files of endocrine evaluations registered in a primary outpatient setting, we selected 483 files on euthyroid subjects (383 females and 100 males) with a normal echoic pattern on US. The inclusion criterion was the absence of thyroperoxidase autoantibodies and drugs known to interfere with thyroid hormone secretion or metabolism. TV was calculated by means of US. Anthropometric characteristics, smoking habits and the district where subjects lived were registered.

RESULTS

Less than 50% of patients were not taking any drug. The percentage of obesity was similar in both sexes. TSH levels were similar in males and females. Median TV was 8.0 mL (IQR: 6.7-9.8 mL) in females and 11.8 mL (9.3-15.6 mL) in males (P<0.0001). In females, TV was greater (P=0.01) in smokers than in non-smokers. In both sexes, the right lobe was significantly (P<0.0001) larger in volume than the left. Post-hoc analysis did not show any differences among age-groups in either females or males. In females, but not in males, TV differed significantly (P=0.0002) according to the district of residence. A significant positive correlation was found in both groups between TV and weight, height, BMI and BSA.

CONCLUSIONS

Reference values of TV in the Ligurian population are now available. TV in the general population could be compared with these normative data.

Influence of sex, age and thyroid function indices on dual-energy computed tomography-derived quantitative parameters of thyroid in patients with or without Hashimoto's thyroiditis

PURPOSE

To study the influence of sex, age and thyroid function indices on dual-energy computed tomography (DECT)-derived quantitative parameters of thyroid in patients with or without Hashimoto's thyroiditis (HT).

MATERIAL AND METHODS

A total of 198 consecutive patients who underwent DECT scan of neck due to unilateral thyroid lesions were retrospectively enrolled. Iodine concentration (IC), total iodine content (TIC) and volume of normal thyroid lobe were calculated. Influences of sex, age and thyroid function indices on DECT-derived parameters in overall study population, subgroup patients with, and those without HT were assessed using Mann-Whitney U test, Student's T-test, and Spearman correlation analyses, respectively, as appropriate.

RESULTS

HT group showed significantly lower IC and TIC, while higher volume than No-HT group (all p < 0.001). The volume was larger in male than that in female in overall study population and No-HT group (p = 0.047 and 0.010, respectively). There was no significant difference in any DECT-derived parameters between low (≤ 35 years) and high (> 35 years) age group in all three groups (all p > 0.05). TPOAb and TgAb correlated positively with IC and TIC, and negatively with volume in overall study population (all p < 0.05). TPOAb and TgAb also correlated positively with IC in HT group (p = 0.002 and 0.007, respectively).

CONCLUSION

DECT-derived parameters of thyroid differed significantly between patients with and without HT. Sex and thyroid function indices could affect the DECT-derived parameters. Aforementioned physiological factors should be considered when analyzing the DECT-derived parameters of thyroid.

Total thyroidectomy for giant nodular goiter guided by pre-operative 3D computed tomography reconstruction and 3D printing: A case report

BACKGROUND

Nodular goiter is a common clinical problem, and thyroidectomy is preferred in patients with obstructive symptoms. Thyroidectomy is a complex procedure with some common complications. Three-dimensional (3D) computed tomography (CT) reconstruction and 3D printing provide visualized 3D anatomical structure, posing an enormously valuable potential in precise surgery with optimal efficacy and minimum complications. Here, we aimed to perform a precise thyroidectomy guided by this technology.

METHODS

The patient was an 80-year-old woman with 10 years of goiter, 1 year of labored dyspnea, and a history of thyroid surgery 62 years ago. In addition to ultrasonography examination, CT images were obtained to construct the 3D model to identify the 3D relationship between the lesion and adjacent structures, and a 3D model of the trachea was created and printed using a 3D printer.

RESULTS

The 3D model clearly presented the diffuse enlargement of the two lobes and isthmus and the compression of the goiter. Under the 3D guidance, the operative resection specimen of the right lobe and isthmus was 12 ´ 7 ´ 5 cm, whereas the left lobe specimen was 12 ´ 9 ´ 6 cm. Nodular goiter and lymphocytic thyroiditis were confirmed by postoperative histopathology. There were no complications after total thyroidectomy except for non-permanent hypocalcemia and hypoparathyroidism.

CONCLUSION

Our results proved that total thyroidectomy for giant goiter is challenging, and 3D image-guided thyroidectomy facilitates precise and safe resection with fewer complications. 3D CT reconstruction and 3D printing can provide anatomical details and may be considered in thyroidectomy planning for patients with giant goiter.

Nutritional iodine status and obesity

Iodine is an essential component of the thyroid hormones, thyroxine and triiodothyronine. Its availability strictly depends on iodine content of foods, which may vary from very low to very high. Inadequate iodine intake (deficiency or excess) may affect thyroid function resulting in hypothyroidism or hyperthyroidism. Based on median urinary iodine concentrations, epidemiological criteria have been established for the categorization and monitoring of nutritional iodine status of a population (or subgroups of populations). Additional methods for iodine intake assessment include measurement of thyroid size (by thyroid palpation or ultrasonography) and of biochemical parameters, such as neonatal thyroid stimulating hormone, thyroglobulin and thyroid hormones.

Recent studies carried out in overweight/obese children and adults provide evidence that body mass index (BMI) may significantly influence the above indicators, thus theoretically affecting the epidemiological evaluation of nutritional iodine status in populations.

In this short review, we analyze current knowledge on the effects of overweight and obesity on indicators of adequacy and monitoring of iodine status, namely urinary iodine excretion and thyroid volume and echogenicity.

Data on urinary iodine excretion in overweight/obese children are divergent, as both increased and reduced levels have been reported in overweight/obese children compared to normal-weight controls.

Whether gastrointestinal surgery may affect iodine absorption and lead to iodine deficiency in patients undergoing bariatric surgery has been evaluated in a limited number of studies, which excluded iodine deficiency, thus suggesting that supplements usually recommended after bariatric surgery do not need to include iodine.

Albeit limited, evidence on thyroid volume and obesity is consistent with a direct relationship between thyroid volume and BMI, irrespective of nutritional iodine status. Finally, a higher frequency of thyroid hypoechoic pattern has been described in overweight/obese children. This finding has been recently related to an increased adipocyte infiltration and thyroid parenchyma imbibition mediated by inflammatory cytokines and should be considered when the frequency of thyroid hypoechoic pattern is used as non-invasive marker to indirectly assess thyroid autoimmunity in monitoring Universal Salt Iodization programs. Further studies, specifically addressing the role of schoolchildren body mass index as a factor potentially influencing iodine intake indicators are needed.

New Reference Values for Thyroid Volume and a Comprehensive Assessment for Influencing Factors in Chinese Adults with Iodine Sufficiency

OBJECTIVES

The reference values for thyroid volume (Tvol) determined by ultrasound require supportive data of normal Tvol from local iodine-sufficient populations. This study aimed to explore new reference values for Tvol in Chinese adults and comprehensively evaluate the factors associated with enlarged Tvol.

METHODS

A cross-sectional study was conducted in Tianjin, China. Tvol was measured by ultrasound in adults with long-term iodine sufficiency. Blood and urine samples were collected to evaluate biochemical indexes, thyroid function, and iodine status.

RESULTS

A total of 1,991 adults from the urban and suburban areas were analysed. The trend of Tvol increasing with age was observed in men under age 40 years and in women under age 52 years. In the quantile regression analyses, we found that body surface area (BSA) (β = 7.22, 95% CI: 5.33, 9.12), thyroid-stimulating hormone (TSH) (β = -1.48, 95% CI: -2.39, -0.57), thyroid nodules (TNs) (β = 6.70, 95% CI: 2.19, 11.22), and metabolic syndrome (MetS) (β = 1.40, 95% CI: 0.63, 2.17) had a strong effect on Tvol at higher percentiles in males. The dominant factors influencing Tvol were BSA (β = 9.64, 95% CI: 2.66, 16.61), TSH (β = -0.78, 95% CI: -1.16, -0.39), and TNs (β = 1.11, 95% CI: 0.43, 1.79) in females. The largest reference values for Tvol based on BSA were 20.18 (17.79, 24.32) mL in males and 15.31 (14.05, 16.70) mL in females.

CONCLUSIONS

Quantile regression analyses showed that a high BSA index, a decreased TSH level, and the prevalence of TNs were essential factors associated with the enlargement of the thyroid gland. Our findings reported the new reference values for Tvol determined by ultrasound based on gender and BSA in Chinese adults.

Assessment of qualitative and quantitative parameters of healthy thyroid gland in adult horses by magnetic resonance imaging

In humans and pets, magnetic resonance imaging (MRI) provides important adjunctive anatomic information about the thyroid and its adjacent structures. To the best of our knowledge, however, no studies have been reported regarding the use of MRI for thyroid evaluation in horses. The aim of this study was to obtain qualitative and quantitative parameters of healthy thyroid gland in adult horses by MRI. Eleven horses were submitted to thyroid MRI evaluation. The healthy thyroid of these animals was ensured by normal examinations performed before (free thyroxine and ultrasound) and after (cytology) to MRI. It was concluded that the dorsal spin-echo T1-weighted, fast spin-echo T2-weighted, sagittal STIR and a three-dimensional T1-weighted gradient echo were the sequences that best characterized the thyroid lobes. Qualitatively, there was a significant variation in the elliptical format of some lobes considering the sagittal plane, which oscillated between rounded and flattened conformation. Excellent reproducibility of the quantitative thyroid parameters obtained was verified. The thyroid gland total volume mean of observers was 14.31 cm³ (±0.69). In relation with comparisons between quantitative parameters of left and right lobes, only differences regarding their respective lengths were observed. Thus, we can infer that the difference in some thyroid lobes format can be explained by the significant variation identified between left and right lobes lengths.

Thyroid function in postpartum psychosis: An exploratory study

The study aimed to compare thyroid function between psychosis with postpartum onset (PPO), psychosis without postpartum onset (PWPO), and normal postpartum females (HC). Twenty women were recruited in each of the three groups. The PPO group had significantly greater psychopathology and shorter episodes compared to the PWPO group. The PPO group was found to have significantly greater right lobe volume than the other groups. The PPO group also had significantly higher FT4 levels than the HC group. We conclude that isolated increase in FT4 and thyroid lobe volumetric changes could be more specifically associated with psychosis of post-partum onset.

Risk factors for hypothyroidism and thyroid hormone replacement after hemithyroidectomy in papillary thyroid carcinoma

PURPOSE

Thyroid lobectomy is now preferred over total thyroidectomy to preserve thyroid function and reduce complications in patients with low-risk papillary thyroid carcinoma (PTC). One inevitable consequence of thyroidectomy includes hypothyroidism. This study aimed to evaluate the risk factors for hypothyroidism and thyroid hormone replacement after hemithyroidectomy in patients with PTC.

METHODS

We retrospectively studied 353 patients with PTC who underwent hemithyroidectomy with or without central neck dissection from January 2012 to January 2019. We excluded patients who had hypo- or hyperthyroidism preoperatively and those who underwent total or subtotal thyroidectomy. We analyzed various risk factors related to postoperative hypothyroidism and thyroid hormone supplementation.

RESULTS

Of the patients, 54.7% showed hypothyroidism after hemithyroidectomy (n=193 with n=157, subclinical hypothyroidism; n=36, overt hypothyroidism). Ninety-one percent of postoperative hypothyroidism cases developed within 7 months postoperatively. Eventually, 43.1% (n=152) of patients received levothyroxine after hemithyroidectomy. Preoperative high thyroid-stimulating hormone (TSH) level and low free thyroxine (fT4) level were significantly associated with postoperative hypothyroidism and the need for thyroid hormone supplementation postoperatively.

CONCLUSION

Preoperative TSH and fT4 levels are predictive risk factors of hypothyroidism and need for supplementation of levothyroxine after hemithyroidectomy in patients with PTC. Finally, approximately 43% of patients need levothyroxine supplementation after hemithyroidectomy, and individual preoperative counseling is necessary for these patients.

"Small Thyroid Gland" in Reproductive Women without Autoimmune Thyroid Disease-Ultrasonographic Evaluation as a Useful Screening Tool for Hypothyroidism

Proper thyroid function is important for women of childbearing age, as hypothyroidism affects fertility, pregnancy and offspring. The upper reference limit for thyrotropin (TSH) in pregnancy was defined as <2.5 mU/L in the first trimester. Recommendations include either universal screening of TSH before pregnancy, or identifying individuals at “high risk” for thyroid illness. “Small thyroid gland” not associated with autoimmune thyroid disease (AITD) seems to be a reason for hypothyroidism and probably should be included in target case finding procedure before pregnancy. The purpose of this cross-sectional study was to analyze relationships between the thyroid volume and its function, and to determine the thyroid volume as a predictive factor for TSH levels above 2.5 µIU/mL in reproductive women without AITD. We included 151 women without AITD, and aged 18–40. Blood and urine samples were analyzed for parameters of thyroid function. Ultrasound examination of the thyroid was performed. The thyroid volume was negatively correlated with TSH. Women with a thyroid volume in the 1st quartile for the study population presented higher TSH levels versus women in the 4th quartile (p = 0.0132). A thyroid volume cut-off point of 9 mL was the predictive factor for TSH levels above 2.5 µIU/mL (p = 0.0037).

Iodine concentration and content measured by dual-source computed tomography are correlated to thyroid hormone levels in euthyroid patients: a cross-sectional study in China

Background

The aim of this study was to investigate the correlation of the dual energy CT measured iodine concentration and total iodine content with blood measured thyroid parameters.

Methods

Forty-three patients with normal thyroid function at our hospital from August 2017 to October 2019 were included in this retrospective study. Dual energy CT was used to scan the neck of thyroid patients. The mean iodine concentration and thyroid tissue volume were measured to calculate the total iodine content of the thyroid. Relevant tests of triiodothyronine (FT3), total triiodothyronine (TT3), total thyroxine (TT4), free thyroxine (FT4), and thyroid hormone (TSH) were conducted. The correlation of the thyroid mean iodine concentration and total iodine content with blood-measured thyroid function was analysed.

Result

The total iodine content in the thyroid was positively correlated with FT3 but negatively correlated with TSH. The mean iodine concentration of the thyroid was positively correlated with both FT3 and TT3.

Conclusion

The thyroid iodine content measured by dual energy CT can be used to determine the human iodine nutritional status and evaluate thyroid function, which will facilitate the diagnosis and treatment of thyroid diseases.

The Clinical Value and Variation of Antithyroid Antibodies during Pregnancy

Antithyroid antibodies, which include thyroid-stimulating hormone receptor antibodies (TRAbs), thyroid peroxidase antibodies (TPOAbs), and thyroid globulin antibodies (TgAbs), are widely known for their tight association with thyroid autoimmune diseases. The variation in all three kinds of antibodies also showed different trends during and after pregnancy (Weetman, 2010). This article reviewed the the physiological changes, while focusing on the variation of thyroid antibodies concentration in women during and after pregnancy, and adverse consequences related to their elevation. Since abnormal elevations of these antithyroid antibodies may lead to adverse outcomes in both mothers and fetuses, special attention must be paid to the titer of the antibodies during pregnancy. The molecular mechanisms of the variations in those antibodies have yet to be explained. The frequency and timing of thyroid antibody measurement, as well as different reference levels, also remain to be elucidated.

AATF and SMARCA2 are associated with thyroid volume in Hashimoto's thyroiditis patients

Thyroid volume of Hashimoto’s thyroiditis (HT) patients varies in size over the course of disease and it may reflect changes in biological function of thyroid gland. Patients with subclinical hypothyroidism predominantly have increased thyroid volume whereas patients with more pronounced hypothyroidism have smaller thyroid volumes. Suggested mechanism for thyroid atrophy is thyrocyte death due to apoptosis. We performed the first genome-wide association study (GWAS) of thyroid volume in two groups of HT patients, depending on levothyroxine (LT4) therapy, and then meta-analysed across. Study included 345 HT patients in total and 6 007 322 common autosomal genetic variants. Underlying hypothesis was that genetic components that are involved in regulation of thyroid volume display their effect in specific pathophysiologic conditions of thyroid gland of HT patients. We additionally performed immunohistochemical analysis using thyroid tissues and analysed differences in expression levels of identified proteins and apoptotic marker between HT patients and controls. We found genome-wide significant association of two loci, both involved in apoptosis, with thyroid volume of HT patients: rs7212416 inside apoptosis-antagonizing transcription factor AATF (P = 8.95 × 10⁻⁹) and rs10738556 near chromatin-remodeling SMARCA2 (P = 2.83 × 10⁻⁸). In immunohistochemical analysis we observed that HT patients with homozygous AATF risk genotypes have decreased AATF expression (0.46-fold, P < 0.0001) and increased apoptosis (3.99-fold, P = 0.0001) in comparison to controls. HT patients with heterozygous SMARCA2 genotypes have decreased SMARCA2 expression, albeit without reaching statistical significance (1.07-fold, P = 0.5876), and significantly increased apoptosis (4.11-fold, P < 0.0001). By two lines of evidence we show that two highly plausible genetic loci, AATF and SMARCA2, may be involved in determining the thyroid volume of HT patients. The results of our study significantly add to the current knowledge of disturbed biological mechanisms in thyroid gland of HT patients.

Large-Scale Comparative Analysis Reveals A Simple Model To Predict The Prevalence Of Thyroid Nodules

Background

The frequency of thyroid nodules (TNs) has increased rapidly in recent decades. We established a simple, effective model to predict TN occurrence by a large-scale comparative analysis of the Chinese population.

Subjects and methods

A total of 13,307 subjects were included to screen risk factors between the case group (TN+) and the control group (TN-) by univariate and multivariate analyses. A simple prediction model formed by a subset of five factors was established. The optimal index points for predicting the prevalence of TNs, the model discriminatory power and the association of the model with the size of TNs were assessed.

Results

Age at diagnosis ≥45 years, female sex, body mass index (BMI) ≥24 kg/m², hypertension, antithyroglobulin antibody (TGAB) ≥16.5 IU/mL were independently related to an increased risk of TNs. The cutoff value of 4 points was found to be the best prediction for the prevalence of TNs in the current study, and the model had better discriminatory power than other single independent predictors. In addition, a positive correlation was also found between the index points and the diameter of TNs.

Conclusion

Based on our prediction model, thyroid high-resolution ultrasound and associated laboratory tests may be necessary for patients with index points ≥4 due to a higher prevalence of thyroid nodules.

Central Hypothyroidism Due to a TRHR Mutation Causing Impaired Ligand Affinity and Transactivation of Gq

CONTEXT

Central congenital hypothyroidism (CCH) is an underdiagnosed disorder characterized by deficient production and bioactivity of thyroid-stimulating hormone (TSH) leading to low thyroid hormone synthesis. Thyrotropin-releasing hormone (TRH) receptor (TRHR) defects are rare recessive disorders usually associated with incidentally identified CCH and short stature in childhood.

OBJECTIVES

Clinical and genetic characterization of a consanguineous family of Roma origin with central hypothyroidism and identification of underlying molecular mechanisms.

DESIGN

All family members were phenotyped with thyroid hormone profiles, pituitary magnetic resonance imaging, TRH tests, and dynamic tests for other pituitary hormones. Candidate TRH, TRHR, TSHB, and IGSF1 genes were screened for mutations. A mutant TRHR was characterized in vitro and by molecular modeling.

RESULTS

A homozygous missense mutation in TRHR (c.392T > C; p.I131T) was identified in an 8-year-old boy with moderate hypothyroidism (TSH: 2.61 mIU/L, Normal: 0.27 to 4.2; free thyroxine: 9.52 pmol/L, Normal: 10.9 to 25.7) who was overweight (body mass index: 20.4 kg/m2, p91) but had normal stature (122 cm; -0.58 standard deviation). His mother, two brothers, and grandmother were heterozygous for the mutation with isolated hyperthyrotropinemia (TSH: 4.3 to 8 mIU/L). The I131T mutation, in TRHR intracellular loop 2, decreases TRH affinity and increases the half-maximal effective concentration for signaling. Modeling of TRHR-Gq complexes predicts that the mutation disrupts the interaction between receptor and a hydrophobic pocket formed by Gq.

CONCLUSIONS

A unique missense TRHR defect identified in a consanguineous family is associated with central hypothyroidism in homozygotes and hyperthyrotropinemia in heterozygotes, suggesting compensatory elevation of TSH with reduced biopotency. The I131T mutation decreases TRH binding and TRHR-Gq coupling and signaling.

Effect of Thyroid Remnant Volume on the Risk of Hypothyroidism After Hemithyroidectomy: A Prospective Study

BACKGROUND

Hypothyroidism is a common sequel after a hemithyroidectomy. Although various risk factors leading to hypothyroidism have been reported, the effect of the contralateral lobe's volume has been understudied. This study aimed to examine the association between the preoperative contralateral lobe's volume and the risk of postoperative hypothyroidism.

METHODS

During a 2-year period, 150 eligible patients undergoing a hemithyroidectomy were evaluated. The volume of the contralateral nonexcised lobe was estimated preoperatively by independent assessors on ultrasonography using the following formula: width (in cm) × depth (in cm) × length (in cm) × (π/6), adjusted for the body surface area (BSA). Postoperative hypothyroidism was defined as serum thyroid-stimulating hormone (TSH) exceeding 4.78 mIU/L. Any significant characteristics in the univariate analysis were entered into the multivariate analysis to determine independent factors.

RESULTS

After a mean follow-up period of 53.5 ± 9.4 months, 44 patients (29.3 %) experienced postoperative hypothyroidism, and 10 of these patients required thyroxine replacement. Hypothyroidism was associated with a higher preoperative TSH level (p < 0.001), a smaller BSA-adjusted volume (p < 0.001), fewer ipsilateral nodules (p = 0.037), and the presence of thyroiditis (p = 0.050). After adjustment for thyroiditis, preoperative TSH (p < 0.001), number of ipsilateral nodules (p = 0.048), and BSA-adjusted volume (p < 0.001) were independent factors for hypothyroidism. Patients with a BSA-adjusted volume smaller than 3.2 ml had a threefold greater hypothyroidism risk than those with a BSA-adjusted volume of 3.2 ml or more (p < 0.001).

CONCLUSIONS

A significant inverse association between the preoperative contralateral lobe's volume and hypothyroidism risk was observed after hemithyroidectomy. Together with a higher preoperative TSH level and fewer ipsilateral nodules, a smaller BSA-adjusted volume measured by preoperative ultrasonography independently predicted hypothyroidism.

Ultrasonographic assessment of thyroid volume in oldest-old individuals

Objective

The aim of this study was to describe the relationship between thyroid volume and age, gender, anthropometric characteristics, and echogenicity in oldest-old subjects in an iodine-sufficient area.

Subjects and methods

The study included 81 independent elderly individuals aged ≥ 80 years (65 [80.2%] women). We determined these individuals' anthropometric characteristics, body mass index (BMI), and lean body mass, as well as thyroid volume and echogenicity by ultrasonography.

Results

We observed that octogenarians and nonagenarians had different profiles of thyroid echogenicity. The volume of the thyroid was smaller in nonagenarians than octogenarians (p = 0.012, r = 0.176), and subjects aged 80-89 years had more often hypoechoic glands than those aged ≥ 90 years (p = 0.01 versus 0.602).

Conclusion

The identification of ultrasonographic differences in oldest-old individuals will contribute to establishing preclinical markers, such as echogenicity, to identify individuals at risk of developing autoimmune thyroid disease. Future prospective studies should identify if 80-89-year-old individuals with hypoechoic glands progress to hypothyroidism, and if the absence of changes in echogenicity (i.e. a normal thyroid parenchyma) would have a positive impact on longevity among nonagenarians.

The presence of anti-thyroglobulin (TgAb) and/or anti-thyroperoxidase antibodies (TPOAb) does not exclude the diagnosis of type 2 amiodarone-induced thyrotoxicosis

PURPOSE

It is widely accepted that type 2 amiodarone-induced thyrotoxicosis (AIT) generally occurs in patients with a normal thyroid gland without signs of thyroid autoimmunity. However, it is currently unknown if the presence of anti-thyroglobulin (TgAb) and/or anti-thyroperoxidase antibodies (TPOAb) in AIT patients without other signs of an underlying thyroid disease may impair the response to glucocorticoid therapy.

METHODS

We performed a pilot retrospective cohort study with matched-subject design and an equivalence hypothesis, comparing the response to glucocorticoid therapy between 20 AIT patients with a normal thyroid gland, low radioiodine uptake, undetectable TSH receptor antibodies and positive TgAb and/or TPOAb (Ab+ group), and 40 patients with the same features and absent thyroid antibodies (Ab- group).

RESULTS

The mean cure time was 54 ± 68 days in the Ab+ group and 55 ± 49 days in the Ab- group (p = 0.63). The equivalence test revealed an equivalent cure rate after 60, 90 and 180 days (p = 0.67, 0.88 and 0.278, respectively). The occurrence of permanent hypothyroidism was higher in the Ab+ group than in the Ab- group (26.3 vs 5.13 %, p = 0.032).

CONCLUSIONS

The presence of TgAb and/or TPOAb does not affect the response to glucocorticoid therapy, suggesting that the patients with features of destructive form of AIT should be considered as having a type 2 AIT irrespective of the presence of TGAb or TPOAb. These patients have a higher risk of developing hypothyroidism after the resolution of thyrotoxicosis and should be monitored accordingly.

The Prevalence of Thyroid Nodules and an Analysis of Related Lifestyle Factors in Beijing Communities

Thyroid nodules (TNs) have annual increasing trends worldwide, and large-scale investigations on the prevalence of TNs in Beijing communities have not been conducted since the introduction of salt iodization in 1995. We performed a cross-sectional study to determine the prevalence of TNs, their epidemiological characteristics, and their correlation with lifestyle factors. A total of 6324 permanent residents aged 18 years or older (mean age, 52.15 ± 11.58 years) from seven representative communities in Beijing were included in the analyses. Once informed consent was obtained, the subjects were asked to complete questionnaires, a physical examination, and thyroid ultrasound. A total of 3100 cases had TNs. The overall prevalence rate was 49.0%, and the age-standardized prevalence was 40.1%, which increased significantly as age increased (p < 0.001). The prevalence was significantly higher in females compared to males (p < 0.001), and it was significantly higher among female current smokers and former smokers compared to non-smokers (p = 0.007). There was no correlation between alcohol consumption and TNs, and there were no significant differences in the prevalence among different groups of taste preference. The prevalence decreased with an increased frequency of seafood intake (p = 0.015) and with higher literacy levels (p < 0.001). The Cochran-Armitage trend test showed that the prevalence significantly increased with decreased physical labor and exercise intensity (p < 0.001, p = 0.009). Logistic regression analysis showed that age (Odds ratio (OR) = 1.039 (1.034-1.044), p < 0.001), the female sex (OR = 1.789 (1.527-2.097)), Body mass index (BMI) (OR = 1.019 (1.005-1.034)), and current smoking habits (OR = 1.246 (1.046-1.483)) were independent risk factors for TNs. Our findings indicate that there is a high prevalence of TNs in Beijing, with a higher prevalence in females than in males. Moreover, the prevalence increases as age increases. Smoking and BMI are independent risk factors for TNs. Therefore, intervention against smoking and weight loss might help reduce the risk of TN occurrence.

Iodine deficiency is higher in morbid obesity in comparison with late after bariatric surgery and non-obese women

BACKGROUND

Iodine deficiency and obesity are worldwide-occurring health problems. Our purpose was to investigate the relationship between morbid obesity and iodine status, including subjects who lost weight after bariatric surgery.

METHODS

Ninety morbidly obese women, 90 women with at least 18 months follow-up after bariatric surgery, and 45 healthy non-obese women were recruited. Urinary iodine concentration (UIC) was measured in a spot urinary sample and expressed as the iodine-to-creatinine ratio.

RESULTS

Obese women showed a significantly lower UIC in comparison with non-obese women (96.6 (25.8-267.3) vs. 173.3 (47.0-493.6) μg/g; p < 0.001), with a lesser proportion of subjects with adequate iodine status (46.6 vs. 83.3 %, p < 0.001). The mean UIC significantly increased among women who underwent bariatric surgery before the collection of the urinary sample (96.6 (25.8-267.3) vs. 131.9 (62.9-496.4) μg/g; p < 0.001). No difference in UIC was detected between laparoscopic Roux-en-Y gastric bypass and laparoscopic sleeve gastrectomy. Univariate analysis showed that UIC negatively correlated with body mass index (BMI) (r = -0.278, p < 0.001) and positively with age (r = 0.206, p = 0.002). Finally, multiple linear regression analyses showed that BMI was independently associated with UIC (beta = -0.312, p < 0.001; R (2) = 0.166).

CONCLUSION

Obesity is an independent risk factor to iodine deficiency, almost in women. Whether more obese population needs to be considered as a vulnerable group and whether bariatric surgery can reverse iodine deficiency still remain to be elucidated.

Thyroid volume and Doppler evaluation of inferior thyroid artery in ultrasound: Comparison between current and previous users of oral contraceptives

BACKGROUND

This study aimed to compare thyroid volume and Doppler sonographic evaluation of the inferior thyroid artery using ultrasound in current and previous users of oral contraceptives (OCs).

METHODS

We evaluated 119 women who either currently use (n = 66) or have previously used OCs (n = 53) using color Doppler ultrasound for thyroid volume and resistance index, peak-systolic, and end-diastolic velocities of the inferior thyroid artery. Previous OC users were divided into two groups: previous OC use for <1 year and previous OC use for ≥1 year.

RESULTS

A comparison of the thyroid volume revealed an increased volume in women with previous OC use for ≥1 year and in current users compared with those with previous OC use for <1 year (previous OC use for ≥1 year: 7.49 mL versus previous OC use for <1 year: 6.13 mL; p < 0.01). The relationship between OC use and an enlarged thyroid remained after adjusting for thyroid-stimulating hormone levels (p = 0.03). There were no differences in the inferior thyroid artery blood flow measurements.

CONCLUSIONS

In healthy women, current use and previous OC use for ≥1 year were associated with increased thyroid volume that was unrelated to increased blood flow in the gland.

Normative Data of Thyroid Volume-Ultrasonographic Evaluation of 422 Subjects Aged 0-55 Years

OBJECTIVE

To establish local normative data of thyroid volume assessed by ultrasonography in subjects aged 0-55 years living in İstanbul, Turkey.

METHODS

Subjects without any known history of thyroid disease, of major surgery and/or chronic disease were enrolled in the study and evaluated by physical examination and thyroid ultrasonography. Thyroid gland and isthmus at usual location, each lateral lobe volume with three dimensions, ectopic thyroid tissue and echogenicity of the gland were assessed.

RESULTS

Initially, 494 subjects were enrolled in the study. Subjects showing heterogeneous thyroid parenchyma (n=21) and/or nodule (n=51) in ultrasonography were excluded. Final analysis covered 422 subjects (216 males, 206 females). Thyroid volume was found to significantly correlate with height, weight, age and body surface area (r=0.661, r=0.712, r=0.772 and r=0.779, respectively; p<0.0001 for all). These correlations were even stronger in subjects younger than 18 years (r=0.758, r=0.800, r=0.815 and r=0.802, respectively; p<0.0001 for all).

CONCLUSION

The study provides updated reference norms for thyroid volume in Turkish subjects which can be used in the diagnosis and follow-up of patients with thyroid diseases.

Thyroid volume and its relation to anthropometric measures in a healthy cuban population

OBJECTIVES

The aim of this study was to describe the thyroid volume in healthy adults by ultrasound and to correlate this volume with some anthropometric measures and other differentiated thyroid cancer risk factors.

STUDY DESIGN

Thyroid volume and anthropometric measures were recorded in a sample of 100 healthy adults, including 21 men and 79 women aged 18-50 years, living in a non-iodine-deficient area of Havana city.

RESULTS

The average thyroid volume was 6.6 ± 0.26 ml; it was higher in men (7.3 ml) than in women (6.4 ml; p = 0.15). In the univariate analysis, thyroid volume was correlated with all anthropometric measures, but in the multivariate analysis, body surface area was found to be the only significant anthropometric parameter. Thyroid volume was also higher in current or former smokers and in persons with blood group AB or B.

CONCLUSION

Specific reference values of thyroid volume as a function of body surface area could be used for evaluating thyroid volume in clinical practice. The relation between body surface area and thyroid volume is coherent with what is known about the relation of thyroid volume to thyroid cancer risk, but the same is not true about the relation between thyroid volume and smoking habit.

The onset time of amiodarone-induced thyrotoxicosis (AIT) depends on AIT type

OBJECTIVE

Considering the different pathogenic mechanisms of the two main forms of amiodarone-induced thyrotoxicosis (AIT), we ascertained whether this results in a different onset time as well.

DESIGN AND METHODS

We retrospectively analyzed the clinical records of 200 consecutive AIT patients (157 men and 43 women; mean age 62.2±12.6 years) referred to our Department from 1987 to 2012. The onset time of AIT was defined as the time elapsed from the beginning of amiodarone therapy and the first diagnosis of thyrotoxicosis, expressed in months. Factors associated with the onset time of AIT were evaluated by univariate and multivariate analyses.

RESULTS

The median onset time of thyrotoxicosis was 3.5 months (95% CI 2-6 months) in patients with type 1 AIT (AIT1) and 30 months (95% CI 27-32 months, P<0.001) in those with type 2 AIT (AIT2). Of the total number of patients, 5% with AIT1 and 23% with AIT2 (P=0.007) developed thyrotoxicosis after amiodarone withdrawal. Factors affecting the onset time of thyrotoxicosis were the type of AIT and thyroid volume (TV).

CONCLUSIONS

The different pathogenic mechanisms of the two forms of AIT account for different onset times of thyrotoxicosis in the two groups. Patients with preexisting thyroid abnormalities (candidate to develop AIT1) may require a stricter follow-up during amiodarone therapy than those usually recommended. In AIT1, the onset of thyrotoxicosis after amiodarone withdrawal is rare, while AIT2 patients may require periodic tests for thyroid function longer after withdrawing amiodarone.

Epidemiology of nodular goitre. Influence of iodine intake

More than one tenth of the world population is to some degree affected by goitre and most of these harbour nodules. The large differences in thyroid disease prevalence between populations may be caused by genetic and environmental factors. Among the latter, iodine deficiency seems by far to be the most important risk factor. Thus, nodular goitre is a condition predominantly seen in iodine deficient areas of the world. In the present review, we evaluated in detail autopsy and ultrasound studies of the thyroid gland. In autopsy studies, large thyroid volumes and high frequencies of goitres have been reported in countries affected by iodine deficiency. Many cross-sectional studies using thyroid ultrasound investigations have been performed world-wide and reported high thyroid volumes and goitre prevalences, and to some extent also high prevalences of thyroid nodules in iodine-deficient countries. Most of these goitres were classified as nodular goitres. On the other hand, few studies have shown that abundant iodine intake may lead to development of diffuse goitres, but world-wide this has been a minor problem compared with development of nodular goitres. In the past century we have observed a trend towards smaller thyroid glands, and hopefully less than 10% of the world population will experience goitre within a few decades.

Overweight, obesity and thyroid cancer risk: a meta-analysis of cohort studies

OBJECTIVE

This meta-analysis examined the relationship between excess body weight or body mass index (BMI) and risk of thyroid cancer.

METHODS

PubMed(®), MEDLINE(®), EMBASE™ and Academic Search™ Premier databases were searched to identify cohort studies examining the effect of being overweight or obese on the risk of thyroid cancer.

RESULTS

The inclusion criteria were met by seven cohort studies (total number of thyroid cancer cases, 5154). The pooled relative risk (RR) of thyroid cancer was 1.13 (95% confidence interval [CI] 1.04, 1.22) for overweight. Obesity was also linked with increased thyroid cancer risk in males and females, the strength of the association increasing with increasing BMI. The combined RR of thyroid cancer was 1.18 (95% CI 1.11, 1.25) for excess body weight (overweight and obesity combined). Being overweight was associated with a significant increase in thyroid cancer risk among non-Asians, but not among Asians. Overweight, obesity and excess body weight were all associated with papillary thyroid carcinoma risk.

CONCLUSIONS

The association between overweight/obesity/excess body weight and thyroid cancer risk was confirmed.

Smoking and thyroid

Current smoking in population surveys is associated with a slight dose-dependent fall of serum TSH, likely secondary to a rise of serum FT4 and FT3 induced by activation of the sympathetic nervous system; it is independent of iodine intake. In contrast, the slightly greater thyroid size in smokers is observed in iodine-deficient but not in iodine-sufficient areas and caused by competitive inhibition of thyroidal iodide uptake by thiocyanate. Smokers have an increased prevalence of nontoxic goitre and thyroid multinodularity, at least in iodine-deficient areas. Current smoking reduces dose dependently the risk of thyroid cancer, which is more pronounced for papillary than for follicular types; the risk in former smokers approaches that of never smokers. The lower TSH and lower body mass index in smokers might contribute to this reduced risk. Current smoking lowers the risk of developing thyroid peroxidase and thyroglobulin antibodies and subclinical and overt autoimmune hypothyroidism; the effect is dose dependent, but disappears within 3 years after quitting smoking. There is evidence from an animal model of experimental autoimmune thyroiditis that anti-inflammatory effects of nicotine are involved. In contrast, smoking is a dose-dependent risk factor for Graves' hyperthyroidism and especially for Graves' ophthalmopathy. Smoking is related to a higher recurrence rate of Graves' hyperthyroidism, a higher risk on Graves' ophthalmopathy after 131I therapy and a less favourable outcome of GO treatment with steroids or retrobulbar irradiation. The observed associations with smoking likely indicate causal relationships in view of consistent associations across studies, the presence of dose-response effects and disappearance of associations after cessation of smoking.

Thyroid Doppler indices in patients with sickle cell disease

OBJECTIVE

To evaluate the intrathyroidal hemodynamic changes and thyroidal volume in sickle cell disease (SCD) patients.

METHODS

Thirty-two patients with homozygous SCD and 32 control subjects were examined with color Doppler ultrasonography. None of the patients and control subjects had clinical or laboratory evidence of thyroid disease.

RESULTS

SCD patients had significantly higher resistance index (RI) and pulsatility index (PI) values and lower thyroid volume compared with control group.

CONCLUSION

Increased intrathyroidal RI and PI and decreased thyroid volume may be due to impaired thyroidal microcirculation. Further and follow-up studies are needed to explain the relationship between Doppler parameters and thyroid functions.

Relationship between goiter and gender: a systematic review and meta-analysis

Several studies have reported inconsistent findings for the effect of gender on goiter prevalence. We undertook a systematic review and meta-analysis to investigate the effect of gender on goiter prevalence in different age groups and with differing iodine status. We systematically searched Medline, Embase, the Cochrane Library and Persian databases for trials published between 1950 and May 2012. We included studies assessing the goiter in both genders using palpation or ultrasonography, without age limitation. Summary estimates of pooled prevalence proportions were calculated with a quality effects model. Of 3286 candidate articles, 143 were eligible (606,714 participants). Proportional prevalence of goiter was greater for females than males 0.54 (95 % CI = 0.53-0.56) versus 0.46 (95 % CI = 0.44-0.47), these proportions for subgroups of longstanding iodine deficiency and recent (<10 years) iodine sufficiency were 0.59 versus 0.41 and 0.54 versus 0.46, respectively; however, no gender difference was observed in proportional prevalence of goiter in the subgroup of longstanding (>10 years) iodine sufficiency (0.50 vs. 0.50). These proportions for grade 1 of goiter were 0.54 versus 0.46 and for grade 2 were 0.63 versus 0.37; for children were 0.54 versus 0.46 and for adults were 0.74 versus 0.26 for females and males, respectively. Subgroup analyses showed that there was an increasing trend in gender differences around the age of 15 years. Goiter is more frequent in females. This gender difference in prevalence of goiter is more prominent in iodine-deficient areas, and with grade 2 of goiter, notably after puberty.

Single lobe disease in cases of advanced endemic goiter: a new phenotype

OBJECTIVES

To report a new phenotype of advanced endemic goiter that affects only one lobe of the thyroid gland.

PATIENTS AND METHODS

This study included 60 patients from the west of Sudan with long-standing unilateral simple endemic goiter that required obectomy, with emphasis on the gross appearance, measurements and cytological features of the contralateral lobe.

RESULTS

Out of 60 patients with unilateral goiter, 50 (83%) were found to have the disease on the ipsilateral lobe only (monolobar goiter). The contralateral lobe in these 50 patients showed no nodularity, and its volume was within the normal limits. All patients with monolobar disease had total lobectomy on the affected side, and postoperatively they continued to have normal blood levels of T3, T4 and TSH.

CONCLUSION

We report a new phenotype of advanced endemic goiter that affects only one lobe of the thyroid gland, and in the presence of a structurally and functionally normal contralateral lobe.

Morbid obesity in women is associated to a lower prevalence of thyroid nodules

BACKGROUND

Few studies have recently showed functional and morphological changes of the thyroid gland in relation to obesity. To our knowledge, no data are available about the prevalence of thyroid nodules in female obese patients. The aim of this study was to investigate the prevalence of thyroid nodules in morbidly obese women.

METHODS

One hundred eight consecutive female obese patients were selected from those referred to our medical and surgery outpatients providing that following criteria were satisfied: (1) affected by morbid obesity (body mass index (BMI) >40 kg/m(2)); (2) no previous diagnosis of thyroid disease; (3) biochemically proven euthyroid state at the time of recruitment. Ninety-seven control subjects, constituted by normo-weight and/or slightly overweight (BMI ≤ 30 kg/m(2)) women, should satisfy the above criteria 2 and 3. All the subjects were submitted to ultrasound investigation.

RESULTS

The two groups of patients displayed no differences for age and fT4 levels. Obese patients clearly showed a lower prevalence of thyroid nodules [odds ratio 0.294, 95% confidence interval 0.206-0.382]. A single nodule was found in 23% of obese patients as compared to 65% of control subjects (p < 0.0001). No difference for age (year) was found between obese and non-obese subjects with nodules (40.5 ± 8.2 vs. 44.2 ± 8.9, respectively, p = 0.07).

CONCLUSIONS

Our data clearly show a significantly lower prevalence of thyroid nodules in morbidly obese patients. Further studies are needed to confirm and to understand this first observation.

Relationship between metabolic syndrome and multinodular non-toxic goiter in an inpatient population from a geographic area with moderate iodine deficiency

BACKGROUND

Obesity and insulin resistance predispose individuals to the development of both metabolic syndrome and non-toxic nodular thyroid diseases.

AIM

The aim of this observational, cross-sectional study is to evaluate the relationship between metabolic syndrome and multinodular nontoxic goiter in an inpatient population from a geographic area with moderate iodine deficiency.

SUBJECTS AND METHODS

We examined 1422 Caucasian euthyroid inpatients. Thyroid volume was determined by ultrasound of the neck. A fine-needle aspiration biopsy was performed to evaluate single thyroid nodules and dominant nodules ≥15 mm in euthyroid multinodular goiter. The diagnosis of metabolic syndrome was made according to the criteria of the American Heart Association/ National Heart, Lung, and Blood Institute.

RESULTS

Of the sample, 277 patients had clinical evidence of multinodular nontoxic goiter, 461 met the criteria for the diagnosis of metabolic syndrome, and 132 were found to have both conditions. After adjusting for age, gender, body mass index, nicotinism, parity, alcohol intake, thyroid function, and metabolic syndrome- related pharmacological treatment, metabolic syndrome was found to be an independent risk factor for the occurrence of multinodular non-toxic goiter. The relationship between metabolic syndrome and multi nodular non-toxic goiter was apparent in both men and women.

CONCLUSIONS

In this study of euthyroid inpatients, we demonstrate that metabolic syndrome is an independent risk factor for the occurrence of multinodular non-toxic goiter in a geographic area with moderate iodine deficiency. We propose that patients meeting the criteria for metabolic syndrome should be screened for the presence of multinodular non-toxic goiter.

Effects of depot growth hormone replacement on thyroid function and volume in adults with congenital isolated growth hormone deficiency

BACKGROUND

Conflicting data exist on the effects of GH replacement therapy (GHRT) on thyroid function and thyroid volume (TV) in GH-deficient (GHD) patients.

AIM

The aim of this study was to assess the effects of GHRT on thyroid function and TV in adults with congenital lifetime isolated GHD (IGHD).

SUBJECTS AND METHODS

We studied 20 GH-naïve adults with IGHD due to a homozygous mutation of the GHRH-receptor gene at baseline, after 6-month depot- GH replacement therapy (pGH), and 6-month washout (6mo). Total T(3), free T(4) (FT(4)), reverse T(3) (rT(3)), TSH, IGF-I, SHBG, and TV were measured; body surface area-corrected TV (CTV) was calculated.

RESULTS

IGF-I and T(3) increased pGH. T(3) levels remained elevated at 6mo. GHRT did not significantly change FT(4), rT(3), TSH, and SHBG. TV and CTV increased pGH and remained elevated at 6mo.

CONCLUSIONS

GHRT in IGHD adults caused an increase in serum T(3) levels and TV, suggesting an important role of the GH-IGF-I axis in thyroid function.

One in five subjects with normal thyroid ultrasonography has altered thyroid tests

The relation between thyroid ultrasonography and laboratory, and the relationship of thyroid volume with clinical and anthropometric parameters, are not well clarified. Aim of the study was to investigate normal and hypoechoic-inhomogeneous not nodular thyroid gland in predicting thyroid tests, and to assess the correlation of thyroid volume with several clinical parameters. The series included 434 subjects (244 with normal thyroid ultrasonography, and 190 with hypoechoic-inhomogeneous thyroid) at their first evaluation. Subjects with normal ultrasonography and skewed tests were re-evaluated after one year. All subjects with normal ultrasound showed normal free-T₄, while TSH was elevated in 9.8% of cases and thyroid antibodies were positive in another 9.8%. In patients with hypoechoic-inhomogeneous thyroid, free-T₄ was low in 33.2%, TSH was elevated in 78.4% and thyroid antibodies were positive in 76.3%. Normal ultrasonography matched with normal tests in 81.1% of cases while hypoechoic-inhomogeneous thyroid in 9.5% (p<0.001). The re-evaluation of tests showed no significant difference. In subjects with both normal ultrasonography and tests, thyroid volume was correlated with age (p=0.001), weight (p=0.003), BMI (p=0.04), body surface area (p=0.002). Thyroid laboratory assessment was different between subjects with ultrasonographically normal or hypoechoic-inhomogeneous thyroid. Thyroid volume of thyroid diseases-free subjects was correlated with age, weight, BMI and body surface area, and this should be of interest to investigate the references of normality of thyroid size.

Thyroid volume measurement in external beam radiotherapy patients using CT imaging: correlation with clinical and anthropometric characteristics

The aim of this study is to define criteria for accurate representation of the thyroid in human models used to represent external beam radiotherapy (EBRT) patients and evaluate the relationship between the volume of this organ and clinical and anthropometric characteristics. From CT images, we segmented the thyroid gland and calculated its volume for a population of 188 EBRT patients of both sexes, with ages ranging from 1 to 89 years. To evaluate uncertainties linked to measured volumes, experimental studies on the Livermore anthropomorphic phantom were performed. For our population of EBRT patients, we observed that in children, thyroid volume increased rapidly with age, from about 3 cm(3) at 2 years to about 16 cm(3) at 20. In adults, the mean thyroid gland volume was 23.5 ± 9 cm(3) for males and 17.5 ± 8 cm(3) for females. According to anthropometric parameters, the best fit for children was obtained by modeling the log of thyroid volume as a linear function of body surface area (BSA) (p < 0.0001) and age (p = 0.04) and for adults, as a linear function of BSA (p < 0.0001) and gender (p = 0.01). This work enabled us to demonstrate that BSA was the best indicator of thyroid volume for both males and females. These results should be taken into account when modeling the volume of the thyroid in human models used to represent EBRT patients for dosimetry in retrospective studies of the relationship between the estimated dose to the thyroid and long-term follow-up data on EBRT patients.

Thyroid function and morphology in subjects with microdeletion of chromosome 22q11 (del(22)(q11))

INTRODUCTION

Monoallelic microdeletion of chromosome 22q11 (22q11DS) is considered to be the commonest human microdeletion syndrome. Abnormalities of thyroid function are sporadically reported in this syndrome, but very few studies have specifically assessed this issue, and thyroid morphology has not been systematically studied.

DESIGN

To evaluate the prevalence of abnormalities of thyroid function and morphology in a cohort of paediatric and adult patients with 22q11DS.

METHODS

Thirty patients with 22q11DS (median age 9.7, range 1.5-43.9 years) were studied. In all subjects, serum free-T(3), free-T(4), TSH, thyroperoxidase, thyroglobulin, and TSHr auto-antibodies, as well as thyroid ultrasonographic data, were evaluated and compared with age- and sex-matched healthy control groups, for paediatric and adult patients.

RESULTS

Fourteen (46.6%) patients showed thyroid hypoplasia involving the entire gland. In all the patients, the volume of the left lobe of the thyroid was significantly reduced (P < 0.01). Among the subjects with thyroid hypoplasia, 10 out of 14 (71%) showed a concomitant heart malformation, a condition that was present in five (31%) of the subjects with a normal thyroid volume (P < 0.05). Seven (23.3%) cases of subclinical hypothyroidism and one (3.3%) case of overt hypothyroidism were identified. Three (10%) patients were positive for thyroid auto-antibodies. Of the patients with overt and subclinical hypothyroidism, five out of eight (62.5%) patients showed thyroid hypoplasia.

CONCLUSIONS

This study confirms the presence of alterations of thyroid function in 22q11DS, and also suggests a frequent occurrence of abnormalities in thyroid morphology in these subjects. Patients with 22q11DS should be monitored for thyroid function, and thyroid ultrasound screening should be considered, especially in those patients with changes in thyroid function or congenital heart malformations. The possible relationship between developmental abnormalities in the heart and the thyroid gland should be confirmed.

Association of thyroid gland volume, serum insulin-like growth factor-I, and anthropometric variables in euthyroid prepubertal children

CONTEXT AND OBJECTIVE

Few studies have focused on the interrelation between thyroid size, anthropometric variables, and IGF-I in adults, but such data are lacking for children. We have investigated thyroid gland volume and several hormonal and anthropometric variables in prepubertal children.

DESIGN AND PARTICIPANTS

A total of 859 prepubertal euthyroid Danish children aged 4-9 yr underwent a thorough clinical investigation, including anthropometrical measurements and determination of TSH, thyroid hormones, autoantibodies, urinary iodine excretion, and thyroid volume (TV) by ultrasound. Longitudinal growth data from birth were available.

RESULTS

TV increased significantly with age (r = 0.487; P < 0.001). Mean TV +/- sd for different age groups were as follows: 4 yr, 2.2 +/- 1.4 ml; 5 yr, 2.5 +/- 1.3 ml; 6 yr, 2.8 +/- 1.3 ml; 7 yr, 3.2 +/- 1.3 ml; 8 yr, 3.5 +/- 1.3 ml; 9 yr, 3.7 +/- 1.3 ml. We found a significant positive association between IGF-I and TV (P < 0.001). Furthermore, in multiple regression analyses, TSH (P < 0.013), free T(4) (P < 0.001), lean body mass (P < 0.001), and body surface area (P < 0.001) as well as other anthropometrical measurements were identified as factors significantly associated with TV. Family history of thyroid disease and presence of incidental abnormal ultrasound findings were also positively associated with TV (P = 0.025 and 0.022, respectively).

CONCLUSIONS

In our cohort of prepubertal Danish children, the GH/IGF-I-axis was positively correlated with thyroid size, suggesting a role in the regulation of thyroid growth. Moreover, anthropometric measurements, in particular body surface area, were the best predictors of TV.