Differences In Thyroid Volume Research Articles

Normative Values for Thyroid Volume and Tracheal Index in Healthy Turkish Newborns in an Iodine Sufficient Region.

The study aims to determine the normal values of thyroid volume and tracheal index in healthy term newborns born in an iodine-sufficient population. Additionally, we investigated the usability of a handheld device for assessing the tracheal index. Thyroid imaging was performed at 0-2 days and 15-30 days using handheld and portable ultrasound devices. Thyroid volume and tracheal index were calculated using standard formulas. A total of 144 healthy term newborns with a mean birth weight 3230 g were enrolled. The normal thyroid volume for the entire population was 0.66 ± 0.25 ml at 0-2 days, which significantly increased to 1.12 ± 0.33 ml at 15-30 days (p<0.01). There were no significant differences in thyroid volume between genders in either age group (p=0.246 and p=0.879). Thyroid volume correlated with birth weight, length, and head circumference, with the strongest correlation being with birth weight (r=0.404, p<0.001; r=0.252, p=0.002; r=0.223, p=0.007, respectively). The tracheal index at 0-2 days was 1.84±0.30 in girls, 1.82±0.27 in boys, and 1.83±0.29 overall. At 15-30 days, it was 1.99±0.23 in girls, 2.00±0.28 in boys, and 1.99±0.25 overall. Similar to thyroid volume, the tracheal index increased with age (p<0.01), with no significant gender differences in either age group (p=0.593 and p=0.886). Thyroid volume and tracheal index were moderately correlated in both measurements (rho=0.538, p<0.01). Measurements of the trachea, and thyroid lobe widths using portable and handheld ultrasound devices were correlated (r=0.449, p<0.01; r=0.638, p<0.01; r=0.497, p<0.01). There was also a correlation between tracheal index measurements using both devices in both the first and second measurements. This study provides normative data on thyroid volumes and tracheal index in newborns from an iodine-sufficient population. The tracheal index can estimate thyroid size when volume calculation is not feasible and handheld ultrasound devices are effective for this assessment.

Comparison of Thyroid Toxicity Profiles in Head and Neck Cancer Patients Irradiated by 3D-Conformal Radiation Therapy and Intensity-Modulated Radiation Therapy

ABSTRACT Background: In spite of recent technical advances in the radiation field, exposure to non-target organs such as the thyroid gland remains unavoidable in locally advanced head and neck cancer (LAHNC) planning, which is associated with late toxicities, and this may affect the lifestyle of cancer survivors. Aim: The purpose of this study was to estimate the incidence of thyroid toxicity in LAHNC patients treated with three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT). To establish its correlation, we have analyzed thyroid profile levels, DVH, and the doses of radiation received by the thyroid volume in both radiotherapy planning methods. Material and Method: Sixty patients with LAHNC enrolled and were divided into two groups treated with 3D-CRT (group A) and IMRT (group B). The patient’s thyroid function test, which consisted of serumT3, T4, and TSH, was done before starting radiotherapy and at 6 months and 12 months follow-up. Absolute thyroid volume, maximum dose, minimum dose, mean dose to the thyroid gland, and percentage of thyroid volume receiving as V10, V20, V30, V40, and V50 were studied. Results: After 6-month post-RT, 6.7% of patients in group A showed biochemical hypothyroidism, whereas biochemical hypothyroidism, sub-clinical hypothyroidism, and hyperthyroidism were observed in 10%, 3.3%, and 10% patients of group B, respectively. After 12 months post-RT, 23.3% of patients in group A showed hypothyroidism. In the 3DCRT group, mean T3 was significantly higher for patients with no hypothyroidism (P &lt; 0.05). Mean T4 was observed to be significantly lower in both the groups in hypothyroid patients (P &lt; 0.05). Mean TSH was significantly higher for hypothyroid patients in the IMRT group (P &gt; 0.01). The difference in thyroid volume and thyroid dose was observed to be statistically significant (P &lt; 0.05). Conclusion: The incidence of thyroid toxicity may be decreased by sparing the volume of the thyroid gland and the thyroid dose kept to a minimum. As per dosimetric parameters, &gt;V40 may predict the risk of developing hypothyroidism after irradiation in LAHNC patients. We recommend regular thyroid function tests on follow-up visits of irradiated patients of LAHNC.

Clinical efficacy of Bupleurum inula flower soup for immune damage intervention in Hashimoto's thyroiditis: A placebo-controlled randomized trial.

Background: Antibody-mediated humoral immune response is involved in the damage process in Hashimoto's thyroiditis (HT). Although the traditional Chinese medicine (TCM) formula bupleurum inula flower soup (BIFS) is often used in HT treatment, it has not been evaluated through high-quality clinical research. Rigorously designed randomized, double-blind, prospective clinical studies are urgently needed to evaluate BIFS for intervening in the HT immune damage process, and to improve clinical prognosis and patient quality of life. Methods: A prospective randomized, double-blind, placebo-controlled trial was used to evaluate the efficacy of BIFS. Fifty participants diagnosed with HT with hypothyroidism were randomly assigned at a 1:1 ratio to the BIFS (levothyroxine with BIFS) or control (levothyroxine with placebo) group. Participants received 8weeks of treatment and were followed for 24weeks. They were monitored for: levels of thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb), and thyroid stimulating hormone (TSH); scores for depression, anxiety, and health-related quality of life (HRQoL); thyroid volume; safety indicators including routine blood tests, liver and kidney functions, and electrocardiogram; and levothyroxine dose. Results: Forty-eight participants completed the study and were included in the final analysis. At baseline, there were no significant between-group differences in the observed indicators (p > 0.05). Post-treatment, compared with the control group, the BIFS group had significantly lower levels of TPOAb (275.77 ± 132.98 vs. 441.78 ± 195.50, p = 0.001), TgAb (385.92 ± 281.91 vs. 596.17 ± 282.26, p = 0.013), and TSH (6.57 ± 3.73 vs. 9.63 ± 5.34, p = 0.001). Compared with the control group, the BIFS group's scores improved significantly for depression (47.00 ± 5.12 vs. 51.04 ± 3.22, p = 0.002), anxiety (43.21 ± 4.22 vs. 48.08 ± 2.81, p = 0.005), and HRQoL physical (62.08 ± 5.97 vs. 57.96 ± 4.71, p = 0.011) and psychological (60.17 ± 5.94 vs. 55.75 ± 7.09, p = 0.024) subscores. At 24-week follow-up, levothyroxine combined with TCM allowed a significantly reduced levothyroxine dose (0.58 ± 0.43 vs. 1.02 ± 0.45, p = 0.001). The post-treatment clinical efficacy rates differed significantly (p = 0.03), with 75% (18/24) for the BIFS group and 46% (11/24) for the control group. There were no significant between-group differences in thyroid volume or safety indicators after eight treatment weeks or at the 24-week follow-up (p > 0.05). Conclusion: The TCM BIFS can effectively reduce thyroid titer, relieve clinical and emotional symptoms, and improve HRQoL in patients with HT. Clinical Trial Registration: https://www.chictr.org.cn/, identifier ChiCTR1900020987.

Study on influential factors and reference values for thyroid volume in Chinese children aged 6-12 years.

The purpose of the current study was to research the factors influencing thyroid volume (TVOL) in 6-12-year-old children and update the reference values. A cross-sectional study was carried out in iodine-sufficient areas of four provinces in China. Urine, edible salt and drinking water samples were collected from children. Children's height, weight and TVOL were measured. Ridge regression was used to screen variables for solving the multicollinearity problem. Quantile regression was used to analyse the relationship between the quantiles of TVOL and other variables. In total, 5653 children aged 6-12 years were enrolled in this study, including 2838 boys and 2815 girls. There was no significant difference in TVOL between boys and girls (P > 0·05). Spearman correlation analysis showed that total TVOL was positively correlated with age, height, weight, body surface area (BSA) and BMI, and the correlation coefficients were 0·616, 0·663, 0·669, 0·685 and 0·479, respectively. Among them, the correlation between TVOL and BSA was the strongest. According to the ridge regression results, age and BSA influenced TVOL, and the ridge regression coefficients were 0·13 and 0·94, respectively. Quantile regression further showed that age and BSA had significant influences on the whole TVOL distribution (P < 0·001). Therefore, the TVOL of children aged 6-12 years in China was mainly influenced by age and BSA, and reference values for TVOL of different genders based on age and BSA were established.

Comparative analysis of five correction methods for thyroid volume by ultrasound and their recommended reference values in Chinese children aged 8-10 years.

Considering the influence of body's growth and development on thyroid volume (TVOL), whether five existed corrected methods could be applied to correct TVOL remains unclear, in terms of Chinese children's increased growth and development trends. This study aimed to compare the applicability of five correction methods: Body Surface Area corrected Volume (BSAV), Body Mass Indicator corrected Volume (BMIV), Weight and Height corrected Volume Indicator (WHVI), Height corrected Volume Indicator 1 (HVI1) and Height corrected Volume Indicator 2 (HVI2) and to establish the reference values for correction methods. The data of Iodine Nutrition and Thyroid Function Survey were used to analyse the differences in TVOL between normal and abnormal thyroid function children. Data of National Iodine Deficiency Disorders Survey were used to compare five correction methods and to establish their reference values. The median urinary iodine concentrations of children surveyed were 256·1 μg/l in 2009 and 192·6 μg/l in 2019. No significant difference was found in TVOL and thyroid goitre rate between children with normal and abnormal thyroid function. In the determination of goitre, HVI1, HVI2, BSAV and BMIV all showed high agreement with TVOL, while the area under the receiver operating characteristic curve (AUC) of WHVI was relatively low for children aged 8 (AUC = 0·8993) and 9 (AUC = 0·8866) years. Most differences of TVOL between light and heavy weight, short and tall height children can be eliminated by BSAV. BSAV was the best corrected method in this research. Reference values were established for corrected TVOL in Chinese children aged 8-10 years by sex.

Effect of change in neck position on thyroid dose and volume in supraclavicular irradiation for breast cancer using conformal technique

AbstractBackground and aim:Radiation exposure to the thyroid gland during breast irradiation can lead to hypothyroidism and this can impact on the quality of life. The aim of this study was to analyse if there is any difference in the radiation dose received by the thyroid gland during supraclavicular irradiation for breast cancer, with two different neck positions—straight or when the head is turned to the contralateral side to the breast being treated, when using a conformal technique.Materials and methods:All patients who received chest wall/breast and supraclavicular irradiation for breast cancer in 2019 in our department were divided into two groups based on the neck position as SN (neck positioned straight) and TN (neck tilted to contralateral side). The volume of thyroid gland, the radiation dose and volume parameters for Dmax, Dmean, and V5 to V40 of the thyroid were tabulated.Results:There were 72 patients included in the study with a mean age of 59 years, with 39 in the SN group and 33 in the TN group. There was no significant difference in thyroid volume between the two groups. Dmean, V15, V20, V25, V30 and V35 were significantly lower in tilted neck patients as compared to straight neck patients.Conclusion:Neck positioned to the contralateral side of the breast primary may be recommended for conformal CT-based radiation planning.

Iodine status and thyroid parameters of pregnant women living in an iodine sufficient area

During the last few decades painstaking efforts have been made to eliminate iodine deficiency throughout the world. Todays in regions where dietary iodine intake is adequate or borderline, the main focus is increasing dietary iodine supply in the target population during pregnancy and the first years of life. Objective: The aim of this study was to obtain longitudinal data on urinary iodine excretion and the changes of maternal thyroid parameters in two groups of healthy women with mild-to-moderate iodine deficiency and iodine sufficiency residing in an iodine replete area of Tehran capital city of IR Iran, for more than one decade. Research designs and methods: The present study is part of a cohort study, investigating the relative influences of iodine intake on thyroid size and function of mothers and their infants during and after pregnancy. A total of 500 pregnant women enrolled from two mother-child health care centers and was divided into group I, with median urinary iodine excretion (MUIE) &lt; 150 µg/L, and group II with MUIE ≥ 150 µg/L. Sonographic thyroid volume measurement, urinary iodine excretion and thyroid function tests were measured sequentially in all pregnant women during the three trimesters (T) of pregnancy. Results: The mean ± SD age of the participants was 25.1 ± 5.1 years. The MUIE in group I and II in the first, second and third trimester were 123 and 250 µg/L, 127 and 166 µg/L, 120 and 150 µg/L, respectively. The MUIE in the third trimester of pregnancy in group I did not differ significantly from the values in the first and second trimesters (p = 0.67), but it did decline significantly in group II (p &lt; 0.001). The median thyroid volume of subjects, in the first, second and third trimesters were 7.8, 8.2 and 8.1 ml in group I and 7.5, 8.0 and 8.4 ml in group II, respectively. No difference in thyroid volume was found between two groups in each of the three trimesters of pregnancy (p &gt; 0.05). The mean (± SD) TSH concentration of subjects in first, second and third trimester was 2.3(± 2.6), 2.1(± 1.8), 2.3(± 1.7) mIU/L in group I and 2.1(± 3.1), 2.1(± 1.8) and 2.0(± 1.3) mIU/L in group II, respectively. The trend of TSH rising in group I was 26.7% and in group II it was 13.3%. The mean TSH value in three trimesters did not differ significantly in either groups (p &gt; 0.05). The mean (± SD) total T4 concentrations of subjects in first, second and third trimesters were 13.2(± 3.4), 13.8(± 3.3), 13.0(± 2.9) µg/dl in group I and 13.1(± 3.2), 13.7(± 2.9), 13.4(± 3.2) µg/dl in group II, respectively. The mean total T4 value in three trimesters did not differ significantly in either groups (p &gt; 0.05). There was no correlation between the thyroid volume and three observed parameters (UIE, total T4 and TSH) during the pregnancy in either groups. Conclusion: Even in areas with well-established universal salt iodization program, pregnancy could be a risk of having iodine deficiency and systematic dietary fortification needs to be implemented in this vulnerable group.

Presencia de nódulos tiroideos en pacientes con síndrome metabólico en un hospital de tercer nivel de atención peruano

Objetivo: comparar la frecuencia de enfermedad nodular tiroidea (ENT) en pacientes con síndrome metabólico (SM) y en pacientes sin SM en un área yodosuficiente. Materiales y métodos: estudio analítico, de casos y controles, comparativo de grupos pareados. Fueron 40 pacientes con SM y 40 controles, pareados por edad y sexo, los cuales acudieron al servicio de Endocrinología del Hospital Cayetano Heredia, Lima - Perú. El peso, talla y la presión arterial fueron tomadas de la historia clínica. Se evaluó el perímetro abdominal y la presencia de acantosis nigricans. Se midió perfil lipídico, glucosa basal y TSH. Se realizó ecografía tiroidea a todos los participantes. Se midió el volumen tiroideo y se consideró clínicamente significativo a nódulos tiroideos &gt; 5 mm. Resultados: el 80 % de la población estudiada en ambos grupos fueron mujeres. Hubo diferencias significativas en el hábito tabáquico, la acantosis nigricans, la TSH, el volumen tiroideo, peso, índice de masa corporal, perímetro abdominal, presión diastólica, glucosa basal, HDL-colesterol y triglicéridos entre ambos grupos. La ENT fue más frecuente en los pacientes con SM que en los pacientes sin SM (40% vs. 12,5% respectivamente, p = 0,015). El odds ratio (OR) para presentar nódulos tiroideos en presencia de SM fue de 4,66 (intervalo de confianza al 95%: 1,34 - 16,24). Hubo diferencia significativa en el volumen tiroideo entre ambos grupos (p = 0,039). Conclusión: en una población de una zona yodosuficiente, el SM estuvo asociado a ENT y al incremento del volumen tiroideo.

MON-584 Iodine Nutrition Status in Pregnancy: Is the Situation in Poland Improving?

Iodine deficiency is considered the most common preventable cause of brain damage worldwide. It is particularly important during pregnancy, as it influences not only mothers but their fetuses as well. The Polish model of iodine prophylaxis is based on the obligatory household salt iodization and recommendation of iodine-containing supplements use by pregnant women. The aim of the study was to assess the current iodine status of pregnant women in Poland, and to compare it with earlier results. Material and methods: 1208 pregnant women aged 16-46 years (median 29 years) were included. 911 of them (75.4%) were investigated between 2007 and 2011, remaining 297 (24.6%) were studied in 2017. A signed informed consent was obtained from every participating woman. The urinary iodine concentration (UIC) in a casual morning sample was assessed by Sandell-Kolthoff reaction. Thyroid volume was measured by ultrasound. Iodine supplements intake was assessed by a questionnaire. The study protocol was approved by the Local Ethics Board. Results: The studied population of pregnant women proved to be iodine insufficient: median UIC was 94.9 mcg/l (lower quartile - 61.85 mcg/l, upper quartile - 149.0 mcg/l). The UIC significantly increased between 2007-2011 and 2018 (median 92.47 mcg/l and 111.45 mcg/l, respectively; p=008), but still did not meet the iodine sufficiency criterion (median UIC between 150 and 249 mcg/l). In only 17.4% of investigated women, UIC value was within the optimal range of 150 to 249 mcg/l: in 17.3% between 2007 and 2011, and 17.5% in 2018. 62.2% of pregnant women were taking iodine supplements: 63.3% of women investigated between 2007 and 2011, and 58.6% in 2011 (p=0.14). The median thyroid volume in the investigated group was 11.8 mL (lower quartile 9.2 mL, upper quartile 15.0 mL). There was no significant difference in thyroid volume between two groups: 11.9 mL in women investigated between 2007 and 2011, and 11.6 mL in 2017. Conclusions. Although during last years iodine status of Polish pregnant women has improved, it has not reached a sufficiency level. Therefore the current Polish iodine prophylaxis model should be adjusted to provide pregnant women with adequate iodine intake.

Effects of Preoperative Iodine Administration on Thyroidectomy for Hyperthyroidism: A Systematic Review and Meta-analysis.

The current guidelines recommend that potassium iodide be given in the immediate preoperative period for patients with Graves' disease who are undergoing thyroidectomy. Nonetheless, the evidence behind this recommendation is tenuous. The purpose of this study is to clarify the benefits of preoperative iodine administration from published comparative studies. We searched PubMed, Embase, Cochrane, and CINAHL from 1980 to June 2018. Studies were included that compared preoperative iodine administration and no premedication before thyroidectomy. For the meta-analysis, studies were pooled with the random-effects model. A total of 510 patients were divided into the iodine (n = 223) and control (n = 287) groups from 9 selected studies. Preoperative iodine administration was significantly associated with decreased thyroid vascularity and intraoperative blood loss. Significant heterogeneity was present among studies. We found no significant difference in thyroid volume or operative time. Furthermore, the meta-analysis showed no difference in the risk of postoperative complications, including vocal cord palsy, hypoparathyroidism/hypocalcemia, and hemorrhage or hematoma after thyroidectomy. Preoperative iodine administration decreases thyroid vascularity and intraoperative blood loss. Nonetheless, it does not translate to more clinically meaningful differences in terms of operative time and postoperative complications.

Variation of normal tissue complication probability (NTCP) estimates of radiation-induced hypothyroidism in relation to changes in delineation of the thyroid gland

Background. To examine the variations of risk-estimates of radiation-induced hypothyroidism (HT) from our previously developed normal tissue complication probability (NTCP) model in patients with head and neck squamous cell carcinoma (HNSCC) in relation to variability of delineation of the thyroid gland.Patients and methods. In a previous study for development of an NTCP model for HT, the thyroid gland was delineated in 246 treatment plans of patients with HNSCC. Fifty of these plans were randomly chosen for re-delineation for a study of the intra- and inter-observer variability of thyroid volume, Dmean and estimated risk of HT. Bland-Altman plots were used for assessment of the systematic (mean) and random [standard deviation (SD)] variability of the three parameters, and a method for displaying the spatial variation in delineation differences was developed.Results. Intra-observer variability resulted in a mean difference in thyroid volume and Dmean of 0.4 cm3 (SD ± 1.6) and -0.5 Gy (SD ± 1.0), respectively, and 0.3 cm3 (SD ± 1.8) and 0.0 Gy (SD ± 1.3) for inter-observer variability. The corresponding mean differences of NTCP values for radiation-induced HT due to intra- and inter-observer variations were insignificantly small, -0.4% (SD ± 6.0) and -0.7% (SD ± 4.8), respectively, but as the SDs show, for some patients the difference in estimated NTCP was large.Conclusion. For the entire study population, the variation in predicted risk of radiation-induced HT in head and neck cancer was small and our NTCP model was robust against observer variations in delineation of the thyroid gland. However, for the individual patient, there may be large differences in estimated risk which calls for precise delineation of the thyroid gland to obtain correct dose and NTCP estimates for optimized treatment planning in the individual patient.

Ultrasound Evaluation of Thyroid Gland Volume in Schoolchildren 7-11 years from West Kazakhstan

Objective: to determine thyroid volume by ultrasound in schoolchildren aged 7 to 11 years, from oil and gas areas of West Kazakhstan. Materials and Methods. During the period from May to December 2013 cross-sectional study was conducted on schoolchildren living in the oil and gas and clean areas of West Kazakhstan. A total of 815 schoolchildren aged 7-11 years who met the study criteria were included in the study. Anthropometry was measured before the ultrasound, then the expert radiologist conducted measurement of thyroid volume using a portable ultrasound machine according to recommendations of WHO. Urinary iodine was tested in 10% of students selected randomly. Results. The prevalence of goiter in our sample using the 97th percentile of the volume recommended by WHO / ICCIDD (2007) was 24.7 ± 1.50% (49.8% girls and 51.2% boys). Average thyroid volume measured by ultrasound in the oil and gas regions was 4.43 ± 1.66 ml, in a safe area of 2.9 ± 1.24 ml. The difference in thyroid volume was statistically significant p &lt;0.0001. The difference in thyroid volume between boys compared areas was statistically significant ( p &lt;0.0001): 4.62 ± 1.75 ml and 2.78 ± 0.93 ml; between girls 4.23 ± 1.53 ml and 3.05 ± 1.52 ml, respectively ( p &lt;0.0001).Mean volume thyroid does not correlate with the age of the participants, but weakly correlated with BMI ( r = 0.3; p &lt;0.0001). Median and 97th percentile thyroid volumes of our subjects were higher than the reference values reported to WHO. Median urinary iodine (UI) was 193 mg/l. Conclusion. Thyroid size of schoolchildren in west region of Kazakhstan is higher than the reference values reported to WHO. The high prevalence of goiter in the areas of oil and gas on of versus iodine-replete conditions available to the regional populations according to urinary iodine (UI) suggests the influence of other goitrogenic factors in the region and requires further study.

Iodine fortification may influence the age-related change in thyroid volume: a longitudinal population-based study (DanThyr)

To assess the individuals' thyroid volume changes after the mandatory nationwide iodine fortification (IF) program in two Danish areas with different iodine intake at baseline (Copenhagen, mild iodine deficiency (ID) and Aalborg, moderate ID). A longitudinal population-based study (DanThyr). We examined 2465 adults before (1997) and after (2008) the Danish IF of salt (2000). Ultrasonography was carried out by the same sonographers using the same equipment, after controlling performances. Participants treated for thyroid disease were excluded from analyses. Overall, median thyroid volume had increased in Copenhagen (11.8-12.2 ml, P=0.001) and decreased in Aalborg, although not significantly (13.3-13.1 ml, P=0.07) during the 11 years of follow-up. In both regions, there was an age-related trend in individual changes in thyroid volume from baseline to follow-up; thyroid volume increased in women <40 years of age and decreased in women >40 years of age. IN A MULTIVARIATE REGRESSION MODEL, HIGHER AGE AT ENTRY WAS A PREDICTOR (P0.05) FOR THYROID VOLUME DECREASE 20% DURING THE FOLLOW-UP PERIOD (WOMEN AGED 4045 YEARS: odds ratio (OR) 4.3 (95% CI, 2.2-8.2); women aged 60-65 years: 5.8 (2.9-11.6)) and individuals of higher age were also less likely to have an increase in thyroid volume (women aged 40-45 years: OR 0.2 (0.1-0.3); women aged 60-65: OR 0.3 (0.2-0.4)). Age-dependent differences in thyroid volume and enlargement had leveled out after the Danish iodization program. Thus, the previously observed increase in thyroid volume with age may have been caused by ID.

SONOGRAPHIC EVALUATION OF THYROID MORPHOLOGY DURING THE NORMAL ESTROUS CYCLE IN THE INDO-PACIFIC BOTTLENOSE DOLPHIN (TURSIOPS ADUNCUS)

Physiologic changes occurring in the thyroid in response to the estrous cycle have been noted in companion animals. However, in bottlenose dolphins, the influence of different reproductive states on thyroid morphology remains unclear. Sonography was used to evaluate the variations of thyroid morphology for nine consecutive estrous cycles of four sexually mature, female Indo-Pacific bottlenose dolphins (Tursiops aduncus). The estrous cycle was divided into two phases for evaluation: the follicular and luteal phases. To compare changes associated with sex, thyroid volumes were measured in the different phases during the estrous cycle of female dolphins and were compared to the ultrasound examinations of the four male dolphins measured over a 2-mo period. In males, there was no significant difference in thyroid volume during the study period (P > 0.05). The thyroid volume measured in combining all estrous cycle phases of the female dolphins was significantly larger than that measured in the male dolphins (P < 0.05). A difference in thyroid volume during the estrous cycle was observed, with the thyroid volume during the follicular phase significantly smaller (P < 0.05) than that of the luteal phase, and is possibly related to the influence of female sex steroids. Thyroid volume variability during estrus should, therefore, be taken into account when examining the thyroid gland of female dolphins.

Thyroid ultrasound in patients with Turner syndrome: Influence of clinical and auxological parameters

To determine thyroid volume and structure by ultrasound (US) in patients with Turner syndrome (TS) compared to healthy controls; to evaluate the frequency and characteristics of autoimmune thyroid disease (ATD) and its association with clinical and auxological parameters. 73 patients and 93 height-matched healthy female controls in the same age range were included in the study. Thirty-two TS patients (43.8%) presented ATD. They had a larger body mass index (BMI) and presented the 45,X karyotype more frequently than those without. They were older, with a higher prevalence of lymphoedema at birth and pterygium colli without statistical significance. Thyroid volume was 20% larger in the presence of ATD (p=0.037). A dyshomogeneous thyroid structure was observed in all patients with ATD and less frequently in those without (p=0.016). Dyshomogeneity in TS without ATD was also associated with older age (p<0.001), larger BMI (p=0.003) and larger thyroid volume (p=0.006). Six TS patients presented solitary thyroid nodules (5 benign nodules). We observed a significant interaction between diagnosis and height (p=0.035) and age (p=0.047), indicating that both age and height conditioned the observed differences in thyroid volume. Most TS patients presented ATD with a normal thyroid function or subclinical hypothyroidism, without goiter. Dyshomogeneous thyroid structure was also observed in TS patients without ATD. In TS, the evaluation of thyroid volume according to chronological age does not seem to be efficient because of a link between height and thyroid volume. The prevalence of nodular thyroid disease is similar to that observed in the general population.

X Chromosome Inactivation Pattern is not Associated With Interindividual Variations in Thyroid Volume: A Study of Euthyroid Danish Female Twins

Ahigher frequency of skewed X chromosome inactivation (XCI) is found in patients with autoimmune thyroid disease (AITD) than in controls. Although goitre is often present in AITD, a recent study failed to show an association between XCI and clinically overt nontoxic goitre. However, the etiology of overt goitre is complex, and the mechanisms influencing thyroid volume may involve fewer factors than the mechanisms underlying overt goitre. In order to examine the impact of XCI on thyroid volume in euthyroid females, we studied whether within cohort (n = 138) and within twin pair (n = 69) differences in XCI are correlated with differences in thyroid volume. XCI was determined by PCR analysis of a polymorphic CAG repeat in the first exon of the androgen receptor gene. Thyroid volume was determined by ultrasound. Neither in the within cohort nor in the within twin pair analysis could we demonstrate a statistically significant association between XCI and thyroid volume: Regression coefficient (beta) = 0.023 (95% confidence interval, -0.062-0.108), p = 0.592 and beta = 0.038 (-0.080-0.156), p = 0.521, respectively. Controlling for potential confounders such as zygosity, age, TSH, smoking habits and use of oral contraceptives did not change the findings. In conclusion, in a sample of euthyroid Danish female twins, we found no evidence of a relationship between XCI pattern and thyroid volume.

Thyroid volume and urinary iodine in school children and adolescents in Slovakia after 40 years of iodine prophylaxis.

The thyroid volume (by ultrasonographic volumetry) was estimated in 4,254 schoolchildren and adolescents 6-18 years of age from 12 districts of Slovakia and urinary iodine (by dry alkaline ashing followed by spectrophotometry) in 1,174 spot urine samples. No differences in thyroid volume or in iodine excretion between individual districts were found. Similarly, no differences in thyroid volume between sexes were found up to the age of 14 years, however, thereafter, such volumes were considerably higher in boys. When comparing our cummulated data with those reported by others for a population with optimal iodine intake, it was found: 1. the medians for most of the examined age groups were slightly higher, 2. the percentage of values which were higher than 97 percentiles of normal population was 3.01 for the age of 6-14 years, while that for the age of 15-18 years was 9.04. Only 35.9% of all values of urinary iodine were in the optimal range (i.e. 10-20 mud/dl), while 56.1 were less than 10 micrograms/dl and 15.9% less than 5 micrograms/dl, the remaining 8.0% over 20 micrograms/dl. In spite of long-term iodine prophylaxis (since 1949), the intake of iodine apparently is still not satisfactory, since a considerable amount of individuals appeared to be iodine deficient on the day of examination. Iodine intake, however, may be marginally sufficient up to the age of about 13-14 years, while later a higher number of enlarged thyroids was found which may be classified as goitre endemy grade I.

The impact of smoking on thyroid volume and function in relation to a shift towards iodine sufficiency

The aim of the study was to investigate whether the influence of smoking on thyroid volume and function changes in relation to a higher iodine intake in the population. The study comprised a total of 8,219 individuals each examined in one of two separate cross-sectional studies performed before (n = 4,649) and after (n = 3,570) a mandatory iodization of salt in year 2000 in two areas with established mild and moderate iodine deficiency. Participants answered questionnaires regarding life style factors and a thyroid ultrasonography was performed. Blood samples were analysed for serum thyroid stimulating hormone, free thyroxin and free tri-iodothyronine. All procedures used were similar in the two cross-sectional studies. The overall difference in thyroid volume between heavy smokers and non-smokers across the age groups was reduced after iodization of salt from 24% (19-29%) to 12% (6-18%). After the iodization the odds ratio for having thyroid enlargement was still increased for smokers (OR: 1.9 (CI: 1.5-2.6)) compared to non-smokers. The aetiological fraction of thyroid enlargement due to smoking was 39.3% before the iodization and 24.2% after the iodization. Like before iodization smokers had a lower mean thyroid stimulating hormone and a higher free thyroxin in serum than non-smokers. Conclusively, in areas approaching iodine sufficiency a decline in the impact of smoking on thyroid volume was seen. The effect of smoking on hormonal level was unchanged after the iodization. Thus the effect of smoking on thyroid volume seems to be dependent on iodine intake, whereas the effect on function seems mainly to depend on other factors.

Three-dimensional ultrasound measurement of thyroid volume in asymptomatic male Chinese

This study was undertaken to determine the accuracy and reliability of volume measurements using 3-D ultrasound (US). Variation of thyroid gland volume with age in asymptomatic Chinese men was also investigated. Volumetric measurements of the phantoms and thyroid glands were performed with a commercially available US machine in conjunction with the 3-D SonoScan Pro workstation. Ten tissue phantoms with volumes of 1.5 to 6.5 mL were measured with 3-D US. A water displacement method was used to measure the actual volume of the phantoms. The measured volumes were compared to the actual volumes. Volumes were measured by four operators to investigate interobserver variation. Thyroid US examinations were performed in 38 asymptomatic male Chinese subjects ages 21 to 72 years. The subjects were categorized into four age groups. In each subject, the volume of the left and right lobes and the isthmus of the thyroid gland were measured with 3-D US, and any variation with age was evaluated. Results showed that the actual volume of the tissue phantoms was highly correlated with the volume measured by the four operators (r = 0.9912 to 0.9977, p < 0.05). Interobserver variation in the volumetric measurements of the tissue phantoms was not significant (ICC = 0.9861). The range of thyroid volume of the subjects was 8.81 to 17.25 mL (mean 12.78 ± SD 2.483), and there was no significant difference in thyroid volume between subjects of different age groups ( p > 0.05). 3-D US is an accurate and reliable method by which to measure thyroid volume. (E-mail: ormying@polyu.edu.hk)

Genetic and environmental causes of individual differences in thyroid size: a study of healthy Danish twins.

Factors such as iodine intake, serum TSH concentration, gender, age, body mass index, parity, and cigarette smoking are thought to influence thyroid size. The purpose of our study was to determine the relative roles of these environmental and physiological factors compared with genetic factors in euthyroid subjects with a clinically normal thyroid gland. A representative sample of self-reported healthy twin pairs was identified through the Danish Twin Registry. A total of 520 individuals divided into 104 monozygotic (MZ), 107 dizygotic same sex (DZ), and 49 opposite sex twin pairs were investigated. After adjustment for age, gender, and other covariates, intraclass correlations were calculated. To elucidate the relative importance of genetic and environmental factors to the variation of ultrasonically determined thyroid volume, quantitative genetic modeling was used. Regression analysis suggested that serum TSH, serum free T(4), gender, age, smoking, and body mass index each played a small, but significant, role for variation in thyroid volume. The intraclass correlations for thyroid volume were consistently higher for MZ than for DZ twin pairs (r(MZ) = 0.71; r(DZ) = 0.18; P < 0.001). Using quantitative genetic modeling, it was calculated that genetic factors (with 95% confidence intervals) accounted for 71% (61-78%) of the individual differences in thyroid volume. Genetic influences are important in the regulation of normal thyroid size. This fits the observation that goiter may be seen also in the absence of evident environmental goitrogens such as iodine deficiency and that not all individuals develop goiter even in iodine-deficient areas.