Association Between Thyroid Nodules And Volume And Metabolic Syndrome In An Iodine-adequate Area:A Large Community-based Population Study

Given their high incidence,thyroid nodule(TN)warrant public attention.Thyroid volume(TV)has been associated with multiple factors,such as iodine deficiency and supply and body mass index(BMI).Metabolic syndrome(MS)comprises many metabolic disturbances,with insulin resistance(IR)being its major component.The aim of this study was to investigate the relationship among TN,TV and MS and its components in an iodine-adequate area in Asia.All participants were asked to complete a questionnaire.After excluding 124 individuals based on the exclusion criteria,we reviewed data from 1741 of 1865 participants.Adopting MS diagnostic criteria,we found 437 and 490 subjects who were MS positive(MS(+))and MS negative(MS(-)),respectively.Comparison of those groups showed that,morbidity among TNs patients in the MS(?)group was higher than that of the MS(-)group.High-density lipoprotein cholesterol(HDL-C)emerged as a protective factor,and waist circumference(WC)and age were risk factors for TN.Moreover,TV was not related to MS,and HDL-C and WC were associated with TV.2 Methods2.1 Study subjectsFrom September 2009 to April 2010,every study participant completed a questionnaire,in which demographic characteristics,family and personal medical history,general health status and current medications were assessed.All 1875 subjects were older than 18 years of age.This community-based population study,was approved by the Ethics Committee of the Shandong Provincial Hospital affiliated with Shandong University.A total of 1741 participants participated in this study.Individuals who met the exclusion criterion were excluded from the study.Three or more of the criteria were used to define MS,according to the International Diabetes Federation(IDF)criteria in 2005.All subjects provided signed informed consent form before participating in the study.2.2 Biochemical evaluationsPeripheral venous blood samples were collected from the participants(on an empty stomach)between 8:00 am and 9:00 am.The serum samples were separated into 3 EP tubes approximately 600 ?L each,after centrifugation and immediately stored at-80 ?.Thyroid function included serum thyroid stimulating hormone(TSH),free triiodothyronine(FT3),free thyroxine(FT4),thyroglobulin antibody(TGAb),and thyroid peroxidase antibody(TPOAb),which were measured through electrochemiluminescence technology using an automatic analyzer(Roche Cobas e601,Immunoassay System,Roche,Switzerland).Total cholesterol(CHOL),triglycerides(TG),low-density lipoprotein cholesterol(LDL-C),HDL-C and insulin were measured using routine enzymatic methods with an Olympus 5400 analyzer.Using the glucose oxidase method,plasma glucose concentrations were measured.The homeostasis model assessment of insulin resistance(HOMA-IR)was used to estimate insulin sensitivity for insulin resistance(IR),which was calculated as fasting insulin(FINS)(mU/L)× fasting plasma glucose FPG(mmol/L)/22.5[11].2.3 Anthropometric measurementsThe heights and weights of the participants without thick clothes and shoes were measured by the same person.Waist circumference was measured at the midpoint between the lower costal margin and the iliac crest using the same tape.In addition,blood pressure(BP),including SBP and DBP,was measured three times in five-minute intervals using a hamnatodynamometer(OMRON HEM7200,OMRON,Japan).2.4 Thyroid evaluationUltrasonography was performed using a Logiq(GE Healthcare,Waukesha,WI,USA)with a 7.5 MHz linear transducer,to test whether they had TNs.The ultrasoiund would register the diameter of the TN if it exceeded 3 mm.As a result,all subjects were divided into two groups:a nodule-free group and a group of individuals with at least one nodule.All types of nodules were recorded including solid nodules and mixed nodules,excluding pure cystic nodules.The ellipsoid formula[volume(mL)= depth(cm)· length(cm)·width(cm)-?/6]was used to calculate thyroid volume(TV,each lobe separately).3 ResultsThis study included 927 participants,including 562 females and 365 males.A total of 232 females and 205 males were MS(+),as diagnosed using the IDF criteria.However,there were 330 females and 160 males in the group of MS(-)individuals.3,1 Using Student's t-test or the Mann-Whitney U test to compare the two groups,we found that various diagnostic factors,such as TG,HDL-C,FBG,SBP,DBP and WC,were related to MS in both males and females.Thyroid function only,including FT3 and FT4,was not correlated with MS.In addition,in the female group,TSH was not correlated with MS.Conversely,there was an association between TSH and MS in the male group.3.2 A X 2 test showed that the morbidity of TNs in the MS(+)group was higher than that of the MS(-)group(X 2= 22.03,p<0.05).Specifically,the prevalence of TNs was 38.29%in the MS(+)group and 17.79%in the MS(-)group.Univariate binary logistic regression analysis showed that TNs were significantly related to MS(p<0.001,OR-2.153,95%CI 1.557-2.977).3.3 A total of 195 participants in this study,including 63 males and 132 females,were diagnosed with MS and TNs.Using univariate binary logistic regression analysis and adjusting for gender,we found that TQ HDL-C,waist circumference(WC),SBP,DBP,fasting blood glucose(FBG)and age were posit:ively related to TN.After adjustment for SBP,DBP and gender,only HDL-C,WC and age were related to TNs(p = 0.0023,OR = 0.45,95%CI 0.27-0.75;p = 0.0036,OR =1.04,95%CI 1.02-1.06;p<0.001,OR = 1.05,95%CI 1.04-1.07,respectively).Therefore,we maintain that HDL-C is a protective factor and that WC and age are risk factors for TN.3.4 The TV was 13.99cm3(11.24,17.06)for all participants,13.22 cm3(10.62,16.17)for females,and 14.99 cm3(11.83,18.15)for males.Partial correlation was used to test the correlation between TV and metabolic components.We found that HDL-C and WC were related to TV,after controlling for age.Therefore,we hypothesized that HDL-C and WC were associated with TV.4 ConclusionOur research demonstrated an association between TN and age,and found that the prevalence of TNs in women was higher than that in men.HDLC was a protective factor for TN.WC was a risk factor for TN.The result hypothesized that HDL-C and WC were associated with TV.