Thyroid Gland Standard For Bangladeshi Population And .

Thyroid Gland Standard for Bangladeshi PopulationTable 1 The number of men, women, and pregnantwomen observed in the study, the means and standard deviation (SD) of thyroid measurements, and the range and95% confidence interval (CI) of the data.Mean SDMen (n Z 84)Age (y)38.86 Right lobe (mm) 12.73 Left lobe (mm) 12.36 Isthmus (mm)3.17 Women (n Z 562)Age (y)32.73 Right lobe (mm) 12.31 Left lobe (mm) 10.88 Isthmus (mm)3.09 Pregnant women (n Z 65)Age (y)28.49 Right lobe (mm) 13.42 Left lobe (mm) 11.66 Isthmus (mm)3.16 Min., max. (95% CI)15.302.212.530.6914, 787.4, 18.57.7, 21.42.2, 2.032.040.7313, 853.5, 19.92.6, 18.81.4, .432.200.7318, 4027.20e29.778.70, 20.6 12.79e14.063.3, 17.5 11.09e12.241.8, 5.32.97e3.36Max. Z maximum; min. Z minimum.gives the range and 95% CI of the data. Eighty-four men, 562women, and 65 pregnant women were studied.Means and SD of the measurements were derived fromthe total data of 711 healthy individuals. The mean size ofthe right lobe of the male participants was 12.73 2.21 mmand of the left lobe was 12.36 2.53 mm. The mean size ofthe right lobe of the female participants was12.31 2.03 mm and of the left lobe was 10.88 2.04 mm.The mean size of the right lobe of the pregnant women was13.42 2.43 mm and of the left lobe was 11.66 2.20 mm.The mean size of the isthmus of the men was3.17 0.69 mm, 3.09 0.73 mm for the women, and3.16 0.73 mm for the pregnant women.Table 2 Thyroid gland standards for Women & Pregnantwomen with comparisons.aWomen(n Z 562)Age (y)Right lobe (mm)Left lobe (mm)pIsthmus (mm)Pregnant women p(n Z 65)Mean SDMean SD32.73 10.5112.31 2.0310.88 2.040.001c,*3.09 0.7328.49 4.9213.42 2.4311.66 2.200.001c,*3.16 0.730.001b,*0.001b,*0.003b,*0.464b* Significant.SD Z standard deviation.aThe mean age was found to be 32.73 10.51 years inwomen and 28.49 4.92 years in pregnant women. The meansize of the right lobe was found to be 12.31 2.03 mm inwomen and 13.42 2.43 mm in pregnant women. The size ofthe mean left lobe was found to be 10.88 2.04 mm in womenand 11.66 2.20 mm in pregnant women. These values werestatistically significant (p 0.05) between the two groups. Themean size of the right lobe versus the left lobe was statisticallysignificant (p 0.05) within the groups.bp value reached from unpaired t-test.cp value reached from paired t-test.103Table 2 shows if there were statistically significant differences between the women & pregnant women’s measurements and within the two groups of women.Table 3 shows whether or not the differences were statistically significant between the men & women’s measurements and within group of women.Table 4 gives the number of individuals excluded fromthe study for different thyroid gland pathologies. Thesepathologies were incidentally found during the study of atotal of 782 individuals. These 71 individuals with pathologies were excluded from the study. They comprised of9.08% of the total participants.Besides the 71 individuals who had no history of anythyroid or parathyroid disease, five more were excluded.Two were excluded because of a history of hypothyroidism,one for hyperthyroidism, and one for hypoplasia of thegland. One had undergone a thyroidectomy for a multinodular goiter (man).DiscussionThe thyroid gland is an endocrine gland consisting of twolateral lobes and a connecting portion called the isthmus.Sonography is an accurate method to calculate thyroidvolume. In approximately one-third of cases, the sonographic measurements of volume differ from the physicalsize estimate derived from examinations [3].In the present study the AP diameter of the thyroid glandwas studied in 711 individuals. The mean AP diameter ofthe right and left lobes in the male participants was12.73 mm (95% CI, range 12.21e13.26 mm) and 12.36 mm(11.78e12.94 mm), respectively. In the women it was12.31 mm (12.14e12.49 mm) and 10.88 mm(10.70e11.06 mm), and in the pregnant women it was13.42 mm (12.79e14.06 mm) and 11.66 mm(11.09e12.24 mm). The mean AP diameter of the isthmus inthe men was 3.17 mm (3.01e3.33 mm), in women it was3.09 mm (3.03e3.16 mm), and in the pregnant women itwas 3.16 mm (2.97e3.36 mm) (Table 1).Table 3 Thyroid gland standards for Men & Women withcomparisons.aMen (n Z 84) Women (n Z 562) pAge (y)Right lobe (mm)Left lobe (mm)pIsthmus (mm)Mean SDMean SD38.86 15.3012.73 2.2112.36 2.530.314c3.17 0.6932.73 10.5112.31 2.0310.88 2.040.001c,*3.09 0.730.001b,*0.0.81b0.001b,*0.345b* Significant.SD Z standard deviation.aThe mean age was found to be 38.86 15.30 years in menand 32.73 10.51 years in women. The mean size of the leftlobe was found to be 12.36 2.53 mm in men and10.88 2.04 mm in women. These values were statisticallysignificant (p 0.05) between the two groups. The mean size ofthe right lobe versus the left lobe was statistically significant(p 0.05) within the group (female patients).bp value reached from unpaired t-test.cp value reached from paired t-test.

104S.Q. RashidTable 4 Individuals excluded from the study for differentthyroid gland pathologies.aPathologies found in 71 or9.08% of normal patientsscannedNo. of Percentages ofcases 71 & of total 782 (%)71Goiter (clinically found)Solitary nodule ( 15 mmdiameter)( 15 mm diameter)Nodules (2 or more; 15 mmdiameter)( 15 mm diameter)Cyst (solitary; 15 mmdiameter)( 15 mm diameter)Cysts (2 or more; 15 mmdiameter)Cyst with solid inside( 15 mm diameter)( 15 mm diameter)Coarse parenchymaHeterogeneous parenchymaHeterogeneous parenchymawith one nodule( 15 mm diameter)3144.23, 0.3819.72, 1.794225.63, 0.5130.99, 2.81282.82, 0.2611.27, 1.02161.41, 0.138.45, 0.7722.82, 0.2625112.82,7.04,1.41,1.41,Figure 3Thyroid nodules in both lobes.0.260.640.130.13aBesides these 71 excluded individuals, five more wereexcluded. Two individuals were excluded for hypothyroidism,one for hyperthyroidism, and one for hypoplasia of the gland.One individual had undergone a thyroidectomy for a multinodular goiter (man).Seventy-six cases were excluded from the study.Seventy-one cases due to different pathologies found during the scans for this study, and five because of a history ofabnormalities and other reasons (Table 4).This study was conducted only on healthy participantswith no complaints, signs, or symptoms related to thyroidor parathyroid disease. The causes for exclusion at the timeof scan were clinical goiter, nodules, cysts, and cysts with asolid inside it. Lesion diameters 15 mm and 15 mm werecounted separately. Participants with coarse or heterogeneous parenchymas were also excluded. Also excludedwere individuals with hypothyroidism and hyperthyroidism,hypoplasia of the gland, and individuals who had undergonethyroidectomies (Figures 3 and 4).In tall individuals, the lateral lobes have a longitudinallyelongated shape on sagittal scans, while in shorter individuals the gland is more oval. As a result, the normaldimensions of the lobes have a wide range of variability. Innewborns, the gland is 18e20 mm long, with an AP diameter of 8e9 mm. By 1-year-of-age, the mean length is25 mm and the AP diameter is 12e15 mm [4].In one Western study on adults, the mean length wasapproximately 40e60 mm and the mean AP diameter was13e18 mm. The mean thickness of the isthmus was 4e6 mm[5]. In the present study the mean AP diameter in adultswas 11e14 mm and the mean thickness of the isthmus wasfound to be 2.97e3.36 mm.In another Bangladeshi study, the measurements of thethyroid gland were given in volume. The mean thyroidFigure 4Thyroid cyst with a solid inside it.volume of the total population was 7.25 1.18 mL. Thethyroid volumes of men (7.57 mL) was greater than those ofwomen (6.93 mL, p Z 0.0004), but no sex differences wereobserved in the ratio of thyroid volume to body weight(men 0.1251 mL/kg; women 0.1250 mL/kg). Thyroid volumewas positively related to body weight but not to age. It wasconcluded that sex differences in thyroid volume are due todifferences in body weight between men and women [6].Thyroid volume is generally larger in patients living inregions with iodine deficiency and in patients who haveacute hepatitis or chronic renal failure; it is smaller in patients who have chronic hepatitis or have been treated withthyroxine or radioactive iodine [7,8].Thyroid volume measurements may be useful for goitersize determination in order to assess the need for surgery,to permit calculation of the dose of I131 needed for treatingthyrotoxicosis, and to evaluate the response to suppressiontreatments [7].Thyroid volume can be calculated using linear parameters or more precisely using mathematical formulas. Amongthe linear parameters the AP diameter is the most precise,because it is relatively independent of possible dimensionalasymmetry between the two lobes. When the AP diameteris more than 2 cm, the thyroid gland may be consideredenlarged. The most precise method of calculating thyroidvolume is an integration of formulas for serial areas obtained from contiguous ultrasound scans [8].

Thyroid Gland Standard for Bangladeshi PopulationIn neonates, thyroid volume ranges from 0.40 mL to1.40 mL, increasing by approximately 1.0e1.3 mL for each10 kg of weight up to a normal volume in adults of10e11 3 mL [8].Ultrasonography can be used to help establish thediagnosis of hypoplasia by demonstrating a diminutivelysized gland [2]. In this study only one case of hypoplasia wasfound which was excluded from the study.Many thyroid diseases can present clinically with one ormore thyroid nodules. Such nodules represent commonand controversial clinical problems. Many of the nodulardiseases of the thyroid gland are clinically occult( 1.5 cm) but can be readily detected using high resolution sonography. Epidemiologic studies estimate that between 4% and 7% of the adult population in the USA havepalpable thyroid nodules, with women being morefrequently affected than men [9,10]. This was also foundin this study in Bangladesh, as women are more frequentlyaffected than men.Although nodular thyroid disease is relatively common,thyroid cancer is rare and accounts for 1% of all malignantneoplasms [11]. Most nodules exceeding 1.5 cm inmaximum diameter should be further evaluated (usually byfine needle aspiration cytology), irrespective of physicaland sonographic features. Nodules under 1.5 cm may befollowed by palpation at the time of the patient’s nextphysical examination [12]. In most cases of incidentallydetected nodules, we recommend a simple follow up ofneck palpation at the time of the patient’s next physicalexamination. Follow-up sonographic examination, radionuclide imaging, fine needle aspiration cytology, or surgicalexcision of such incidental nodules is rarely necessary in ourpractice [2].Of 1000 consecutive hypercalcemic patients, 410 (41%)had sonographically visible nodules, of which only 80 (8%)were clinically palpable. A similarly high prevalence ofsonographically detected thyroid abnormalities wasrecently reported in Finland [13]. In this study of 101women with no previous thyroid or parathyroid disease, 36%had one or more sonographically visible nodules. A somewhat higher prevalence of thyroid nodules has beendetected in the autopsy of patients who had clinicallynormal thyroid glands; 49.5% had one or more grossly visiblenodules [14].Thus, high-resolution sonography can detect almost asmany nodules as are demonstrated by careful pathologicexamination, and both studies showed a direct relationshipbetween the prevalence of thyroid nodules and patientage. A similar relationship was also noticed in the presentstudy.Although these studies have shown a high prevalence ofthyroid nodules detected by autopsy and sonography, theprevalence of thyroid malignancy reported in them wasonly 2% and 4%, respectively, with most cases (90%) beingoccult ( 1.5 cm) papillary cancers [14,15]. The vast majority of patients with occult papillary thyroid cancer havean excellent prognosis, with essentially no reduction in lifeexpectancy and no morbidity from appropriate surgicaltherapy. Further evidence that most subclinical thyroidcancers have a benign natural history, is the fact that theannual incidence of clinically detected thyroid cancer isonly 0.005% (5/100,000 people) [11,16].105If 90% of those cancers are papillary and thereforeeminently curable after they become clinically apparent, itseems both impractical and imprudent to pursue a diagnosisof all the small nodules detected incidentally with highresolution sonography [2].Several thyroid diseases are characterized by diffuserather than focal involvement. Recognition of diffuse thyroid enlargement on sonography can often be facilitated bynoting the thickness of the isthmus. Normally it is a thinbridge of tissue measuring only a few millimeters in the APdimension. With diffuse thyroid enlargement, the isthmusmay be up to 1 cm or more in thickness [2].The limitation of this study was that it was carried out inan urban setting. A few rural individuals, who traveled tothe city to see the doctors for other reasons, wereincluded. Otherwise the participants were mainly citydwellers of the capital city of Dhaka in Bangladesh. Thoughmost are migrants from rural areas from all overBangladesh, over many years.ConclusionA nomogram of thyroid size using a linear parameterdAPdiameterdhas been prepared in this study using highresolution ultrasound. Comparisons have been made between right and left lobe sizes and between differentgroups. The prevalence of unknown thyroid gland pathologies in a normal Bangladeshi population was also determined in this study, with 9.08% of normal individuals foundto have some pathology during the scan.RecommendationStudies should be carried out to prepare population specific nomograms of different glands. This will aid in thedetermination of abnormal sized glands more accurately,using ultrasonography, in a particular population. Also, ananalysis of thyroid size and the incidence of pathologiclesions among the young and aged population isrecommended.References[1] Leonhardt WC. The thyroid and parathyroid glands. In:Curry RA, Tempkin BB, editors. Sonography. 2nd ed. St. Louis,MO: Saunders; 2004. p. 367e83.[2] Solbiati L, Charboneau JW, James EM, et al. The thyroidgland. In: Rumack CM, Wilson SR, Charboneau JW, editors.Diagnostic Ultrasound. 2nd ed. St. Louis, MO: Mosby; 1998.p. 703e29.[3] Jarløv AE, Hegedus L, Gjorup T, et al. Accuracy of the clinicalassessment of thyroid size. Dan Med Bull 1991;38:87e9.[4] Toma P, Guastalla PP, Carini C, et al. In: Fariello G, Perale R,Perri G, Toma P, editors. Ecografia Pediatrica. Milno:Ambrosiana; 1992. p. 139e62.[5] Solbiati L. La tiroide e learatiroidi. In: Rizzatto G, Solbiati L,editors. Anatomia ecografica: quadri normali, varianti e limiticon il patologico. Milano: Masson; 1992. p. 35e45 [in Italian].[6] Bhattacharjee PK, Hasan M, Nahar N, et al. The determinationof thyroid volume by ultrasound and its relation to bodyweight, age and sex in normal Bangladeshi subjects.Bangladesh J Ultrason 2001;8:31e6.

106[7] Kerr L. High-resolution thyroid ultrasound: the value of colorDoppler. Ultrasound Q 1994;12:21e43.[8] Yokoyama N, Nagayama Y, Kakezono F, et al. Determination ofvolume of the thyroid gland by a high-resolution ultrasonicscanner. J Nucl Med 1986;27:1475e9.[9] Rojeski MT, Gharib H. Nodular thyroid disease: evaluation andmanagement. N Engl J Med 1985;313:228e36.[10] Van Herle AJ, Rich P, Ljung BME, et al. The thyroid nodule.Ann Intern Med 1992;96:221e32.[11] Grebe SKG, Hay ID. Follicular cell-derived thyroid carcinoma.In: Arnold A, editor. Cancer treatment and research. Endocrine neoplasms. Norwell, MA: Kluwer Academic; p. 91e140.[12] Giuffrida D, Gharib H. Controversies in the management of cold,hot, and occult thyroid nodules. Am J Med 1995;99:642e50.S.Q. Rashid[13] Brander A, Viikinkoski P, Nickels J, et al. Thyroid gland: ultrasound screening in middle-aged women with no previousthyroid disease. Radiology 1989;173:507e10.[14] Mortensen JD, Woolner LB, Bennett WA. Gross and microscopic findings in clinically normal thyroid glands. J ClinEndocrinol Metab 1955;15:1270e80.[15] Horlocker TT, Hay JE, James EM, et al. Prevalence of incidental nodular thyroid disease detected during highresolution parathyroid ultrasonography. In: Medeiros-Neto G,Gaitan E, editors. Frontiers in thyroidology, Volume 2. NewYork: Plenum Medical Book Co.; 1986. p. 1309e12.[16] Hay ID. Thyroid cancer. Curr Ther Int Med 1991;3:931e5.

between two groups. A table of the unknown thyroid pathologies detected during the study, found in 71 individuals or 9.08% of all participants, was also prepared. Conclusion: These nomograms will aid in differentiating normal from abnormal measurements of thyroid glands in the Bangladeshi population. This study also presents the prevalence of un-