Measurement of thyroid blood flow area is useful for diagnosing the cause of thyrotoxicosis

High Diagnostic Accuracy of Thyroid-Stimulating Hormone (TSH) Receptor Antibodies in Distinguishing Graves' Disease and Subacute Thyrotoxicosis in the Indian Population

BACKGROUND AND OBJECTIVE

Thyrotoxicosis is a common clinical condition encountered in endocrine practice. Graves' disease and subacute thyroiditis are the two common causes of thyrotoxicosis and often have overlapping clinical and biochemical features. 99mTc thyroid scintigraphy is the most commonly used confirmatory test to differentiate the two conditions but is not available in the majority of the second-tier cities of India. However, obtaining thyroid stimulating hormone (TSH) receptor antibodies (TSHrAb), another accurate test to differentiate the two conditions, in second-tier cities by outsourcing to labs in major cities is a feasible option nowadays. However, the data on the performance of TSHrAb to differentiate the two conditions in Indian patients is limited. Hence, we have evaluated the diagnostic accuracy of TSHrAb in the Indian population to differentiate Graves' disease and subacute thyroiditis.

MATERIALS AND METHODS

This prospective study was conducted on 115 consecutive newly diagnosed thyrotoxicosis patients presenting to the Department of Endocrinology at a tertiary health care centre in India. Clinical parameters like throat pain, duration of symptoms, and grade of goitre were noted. Measurement of total tri-iodothyronine (TT3), total thyroxine (TT4), TSH, TSHrAb, and 99mTc thyroid scintigraphy were performed in all participants. All participants were followed up at least for six months after the recruitment. Increased tracer uptake (>4%) and/or increased thyroid to parotid trace uptake ratio (>2.5) were used to diagnose Graves' disease.

RESULTS

Eighty-one and 34 patients were diagnosed with Graves' disease and subacute thyroiditis, respectively. TT3/TT4 ratio had low diagnostic accuracy (area under the curve (AUC): 0.6, best cut-off: 15.6, sensitivity: 53.1%, specificity: 79.4%). TSHrAb had the best AUC (0.9) to distinguish Graves' disease from subacute thyroiditis (cut-off: 2.0 IU/L, sensitivity: 97.5%, specificity: 100%). In contrast, the kit manufacturer's reference range (1.75 IU/L) was slightly more sensitive (98.8%), but less specific (94%).

CONCLUSION

The TT3/TT4 ratio is not a good test to differentiate Graves' disease and subacute thyroiditis. TSHrAb is accurate in distinguishing Graves' disease from subacute thyroiditis and a level of 2.0 may be a more accurate cut-off to differentiate the two conditions in the Indian population.

Duplex Hemodynamic Parameters of Both Superior and Inferior Thyroid Arteries in Evaluation of Thyroid Hyperfunction Disorders

Background

Thyrotoxicosis may be caused by Graves’ disease or destructive thyroiditis. Differentiation between causes of thyrotoxicosis is crucial as management will differ. ^99mTechnetium (Tc)-pertechnetate thyroid scintigraphy is currently the gold standard for this purpose, however, is expensive and uses ionizing radiation.

Objective

To evaluate the role of color flow Doppler Ultrasound (CDU) of the superior thyroid (STA) and inferior thyroid arteries (ITA) as an inexpensive, non-invasive tool that can aid in differentiating between Graves’ disease and thyroiditis and compare it with thyroid scintigraphy.

Methods

Sixty-nine patients with newly-diagnosed thyrotoxicosis and 30 controls were enrolled. Thyroid functions, thyroid scintigraphy, and CDU of STA and ITA with measurements of peak systolic velocity (PSV) and end diastolic velocity (EDV), were performed. According to thyroid scintigraphy results, patients were divided into two groups: 42 patients with Graves’ disease and 27 patients with thyroiditis.

Results

PSV and EDV of both STA and ITA were significantly higher in patients with Graves’ disease than thyroiditis (p-values <0.001). The STA-PSV had an equal sensitivity and specificity of 66.7%; cut-off value 76.57 cm/s, while those of STA-EDV were 73.8%, and 77.8% respectively; cut-off value 28.22 cm/s. ITA-PSV had a sensitivity and specificity of 76.2% and 77.8%, respectively; cut-off value 62.12 cm/s), while those of ITA-EDV were 78.6% and 77.8%, respectively; cut-off value 5.22 cm/s.

Conclusion

CDU parameters of the STA and ITA could be used as an alternative to thyroid scintigraphy for discriminating between Graves’ disease and thyroiditis.

Diagnostic Utility of Mean Peak Systolic Velocity of Superior Thyroid Artery in Differentiating Graves' Disease from Thyroiditis

Background Differentiating Graves’ disease from thyroiditis can be at times clinically challenging. The gold standard test (thyroid nuclear imaging scan) is expensive, not routinely available, and has radiation exposure. Color Doppler ultrasonography of thyroid represents a suitable alternate which can be used for differentiating these conditions by studying thyroid blood flow parameters.

Aim We aimed to investigate the use of thyroid blood flow parameters’ assessment of the superior thyroid artery (STA) and common carotid artery (CCA) with color Doppler ultrasonography for differentiating Graves’ disease from thyroiditis.

Materials and Methods This is a cross-sectional study on 111 patients with newly diagnosed thyrotoxicosis (82 with Graves’ disease and 29 with thyroiditis) and 45 years of age and sex-matched healthy controls. All patients underwent detailed clinical and necessary investigations. Color Doppler ultrasonography of the thyroid gland and spectral flow analysis of both superior thyroid arteries was done using standard protocol. Sensitivity and specificity for mean peak systolic velocity of STA (STA-PSV) cut-offs were calculated using receiver operating characteristic curves.

Results Patients with Graves’ disease have significantly higher free tri-iodothyronine (FT3) levels, free thyroxine (FT4) levels, antithyroid stimulating hormone receptor antibody (TRAb) levels, and thyroid volume as compared with those with thyroiditis. The mean STA-PSV of patients with Graves’ disease was significantly higher than thyroiditis and control group. Mean STA-PSV greater than 54.3 cm/s had 82.9% sensitivity and 86.2% specificity in diagnosing Graves’ disease. Mean PSV-STA/PSV-CCA ratio of 0.40 was 80.5% sensitive and 86.2% specific for Graves’ disease.

Conclusion Mean STA-PSV has high sensitivity and specificity in differentiating Graves’ disease from thyroiditis and can be used routinely in clinical practice as a cheap and invaluable diagnostic tool.

Rapid Differential Diagnosis of Thyrotoxicosis Using T3/T4 Ratio, FT3/FT4 Ratio and Color Doppler of Thyroid Gland

CONTEXT

Establishing the etiology of thyrotoxicosis is of utmost importance to plan the appropriate line of therapy. However, certain scenarios such as absence of pathognomonic clinical features of Graves' disease in some patients, or non-availability of radionuclide scanning and newer generation TRAb assays especially in resource-poor settings, necessitates utilization of other, simple and effective measures to differentiate between the two common causes of thyrotoxicosis, Graves' disease (GD) and Destructive thyroiditis (DT).

AIMS

The aim of this work was to study the role of FT3/FT4 ratio, T3/T4 ratio and color flow Doppler ultrasound in treatment-naïve patients with thyrotoxicosis, in comparison to Tc-99m pertechnetate thyroid scanning in the differentiation of thyrotoxicosis due to GD and DT.

MATERIALS AND METHODS

Clinical data was collected from all study subjects. Thyroid function tests including FT3, FT4, T3, T4 and TSH, TSH Receptor Antibody (TRAb), Technetium Tc 99m pertechnetate scan and the mean peak systolic velocity in inferior thyroid artery (mean PSV-ITA) by color Doppler ultrasonography of thyroid gland was done in all patients.

RESULTS

A total of 83 treatment-naïve patients with thyrotoxicosis (61 with GD and 22 with DT) were studied. Mean PSV-ITA, T3/T4 ratio and FT3/FT4 ratio showed a sensitivity of 85.2%, 73.8%, and 77.04%, and a specificity of 90.9%, 72.7%, and 59.09%, respectively. The three parameters in combination yielded a positive predictive value of 100% in the diagnosis of Graves' disease.

CONCLUSION

Results of this study show that inferior thyroid artery blood flow, T3/T4 ratio and FT3/FT4 ratio are useful parameters in the differentiation between GD and DT.

Clinical applications of Doppler ultrasonography for thyroid disease: consensus statement by the Korean Society of Thyroid Radiology

Doppler ultrasonography (US) is widely used for the differential diagnosis of thyroid nodules, metastatic cervical lymph nodes in patients with thyroid cancer, and diffuse parenchymal disease, as well as for guidance in various US-guided procedures, including biopsy and ablation. However, controversies remain regarding the appropriate use and interpretation of Doppler US. Therefore, the Korean Society of Thyroid Radiology organized a taskforce to develop a consensus statement on the clinical use of Doppler US for thyroid disease. The review and recommendations in this article are based on a comprehensive analysis of the current literature and the consensus of experts.

Quantitative Color Doppler Ultrasonography Measurement of Thyroid Blood Flow in Patients with Graves' Disease

BACKGROUND

Graves' Disease is an autoimmune disorder characterized by increased levels of thyroid hormones correlated with increased thyroid blood flow. Thyroid scintigraphy is an important and conventional method. However, it has limited accessibility, has ionizing radiation, and is expensive.

OBJECTIVES

To investigate the thyroid blood flow in patients with Graves' Disease by color Doppler Ultrasonography and a newly developed software Color Quantification.

METHODS

Forty-one consecutive subjects with GD and 41 healthy controls were enrolled. Color Doppler ultrasonography parameters of the thyroid arteries and Color Quantification values of the gland were measured by a radiologist. The correlations between thyroid blood flow parameters, levels of 99mTechnetium pertechnetate uptake, thyrotropin, and free thyroxine were evaluated. The diagnostic performances of these parameters were investigated.

RESULTS

The peak systolic-end diastolic velocities of thyroid arteries and Color Quantification values were increased in the study group (p < 0.05 for all). We observed negative correlations between thyrotropin levels and peak-systolic and end-diastolic velocities of superior thyroid arteries and Color Quantification values. There were positive correlations between 99mTechnetium uptake levels and thyroid blood flow parameters (p < 0.05 for all). In the diagnostic performance of thyroid blood flow parameters, we observed utilities significantly in peak-systolic and end-diastolic velocities of thyroid arteries and Color Quantification values (p < 0.05 for all).

CONCLUSION

The increased peak-systolic and end-diastolic velocities of thyroid arteries, and increased Color Quantification values might be helpful in the diagnosis of Graves' Disease.

Comparison between peak systolic velocity of the inferior thyroid artery and technetium-99m pertechnetate thyroid uptake in differentiating Graves' disease from thyroiditis

OBJECTIVES

The differentiation between the various etiologies of thyrotoxicosis, including those with hyperthyroidism (especially Graves' disease [GD], the most common cause of hyperthyroidism) and without hyperthyroidism (like thyroiditis), is an important step in planning specific therapy. Technetium-99m (99mTc) pertechnetate thyroid scanning is the gold standard in differentiating GD from thyroiditis. However, this technique has limited availability, is contraindicated in pregnancy and lactation, and is not helpful in cases with history of recent exposure to excess iodine. The aim of this study was to identify the diagnostic value of the peak systolic velocity of the inferior thyroid artery (PSV-ITA) assessed by color-flow Doppler ultrasound (CFDU) and compare the sensitivity and specificity of this method versus 99mTc pertechnetate thyroid uptake.

SUBJECTS AND METHODS

We prospectively analyzed 65 patients (46 with GD and 19 with thyroiditis). All patients were evaluated with clinical history and physical examination and underwent 99mTc pertechnetate scanning and measurement of TRAb levels and PSV-ITA values by CFDU. The diagnosis was based on findings from signs and symptoms, physical examination, and 99mTc pertechnetate uptake.

RESULTS

Patients with GD had significantly higher mean PSV-ITA values than those with thyroiditis. At a mean PSV-ITA cutoff value of 30 cm/sec, PSV-ITA discriminated GD from thyroiditis with a sensitivity of 91% and specificity of 89%.

CONCLUSION

Measurement of PSV-ITA by CFDU is a good diagnostic approach to discriminate between GD and thyroiditis, with sensitivity and specificity values comparable to those of 99mTc pertechnetate thyroid uptake.

Mean peak systolic velocity of superior thyroid artery for the differential diagnosis of thyrotoxicosis: a diagnostic meta-analysis

BACKGROUND

Thyrotoxicosis is often caused by destructive thyroiditis (DT) or Graves' disease (GD), and a prompt and accurate differential diagnosis for thyrotoxicosis is needed as management strategy differs. A meta-analysis of published literature was performed to evaluate the diagnostic accuracy for differentiating GD from DT patients by the measurement of mean peak systolic velocity of superior thyroid artery (STA-PSV) using ultrasonography.

METHODS

The databases of Embase, Pubmed, Cochrane, Web of Science, Wanfang, and CNKI were retrieved without time limit to identify eligible studies. The statistical information and scientific quality were assessed and classified. The data were analyzed using Stata12.0 software.

RESULTS

A total of 11 studies with 1052 cases only from Asia were included. Meta-analysis results showed the pooled sensitivity and pooled specificity of STA-PSV by ultrasonography were 0.86 (95% CI, 0.80-0.90) and 0.93 (95% CI, 0.86-0.97) in distinguishing GD from DT, respectively, with the AUC of 0.94 (95% CI, 0.92-0.96) .

CONCLUSION

STA-PSV by ultrasonography is a useful diagnostic method in differentiating GD from DT. More studies from other countries are needed to further evaluate the accuracy of STA-PSV for the differential diagnosis of thyrotoxicosis.

Scintigraphic Profile of Thyrotoxicosis Patients and Correlation with Biochemical and Sonological Findings

INTRODUCTION

Thyrotoxicosis is a spectrum of disorder with a rather common clinical presentation with different aetiologies. The aetiological diagnosis is important as the management differs. It is essential to accurately diagnose the cause before starting treatment. Scintigraphy of thyroid helps in differentiating accurately the various causes. USG is routinely being advocated and T3/T4 ratio has also been used.

AIM

This study aims to evaluate the scintigraphic profile of thyrotoxicosis patients and to correlate biochemical and USG findings with scintigraphy.

MATERIALS AND METHODS

A total of 60 newly diagnosed thyrotoxicosis patients based on biochemical reports were included in the study. They underwent further evaluation with ultrasonography and 99mTc scintigraphy.

RESULTS

Of 60 patients of thyrotoxicosis, 45 cases were of Grave's disease, 10 cases were of thyroiditis and five cases were of Toxic Multinodular Goiter (MNG). The clinical characteristics were helpful in establishing the diagnosis in only six (10%) patients who presented with classic features of Grave's disease with ophthalmopathy. T3/T4 ratio greater than 20 was seen only in 29 (66%) patients of Grave's disease and also in three (33.33%) of thyroiditis patients. USG had a sensitivity and specificity of 81.82% and 93.75% in diagnosing Graves' disease and 100% and 82.4% in diagnosing thyroiditis respectively.

CONCLUSION

Clinical findings do not help in accurately delineating aetiological diagnosis of thyrotoxicosis. Serum T3/T4 ratio when used as a criterion has marked overlap between the various conditions causing thyrotoxicosis. USG has reasonable sensitivity however, misses many cases of early Grave's disease. Follow up scintigraphy helps in a small population with resolving thyroiditis or early Grave's disease where the initial scintiscan is normal or inconclusive.

An Advantageous Role of Spectral Doppler Sonography in the Evaluation of Thyroid Dysfunction During the Postpartum Period

OBJECTIVES

To evaluate the diagnostic value of spectral Doppler sonography in women with thyroid dysfunction during the first postpartum year.

METHODS

This prospective observational clinical study included 83 consecutive untreated women: 32 with hyperthyroid postpartum thyroiditis, 32 with hypothyroid postpartum thyroiditis, and 19 with Graves disease, which first appeared within 12 months after delivery. Thyrotropin, free thyroid hormones, thyroid peroxidase antibodies, thyroglobulin antibodies, and thyrotropin receptor antibodies were measured. With a 7.5-MHz linear transducer, we measured the thyroid volume and peak systolic velocity (PSV) at the level of intrathyroid arteries.

RESULTS

Hyperthyroid postpartum thyroiditis appeared significantly earlier (mean ± SD, 4.4 ± 1.9 months after delivery) than hypothyroid postpartum thyroiditis (6.5 ± 2.1 months) and Graves disease (7.2 ± 2.7 months; P< .001). The thyroid volume in hyperthyroid postpartum thyroiditis (9.7 ± 6.3 mL) was significantly lower than in hypothyroid postpartum thyroiditis (14.7 ± 10.2 mL; P = .030) and Graves disease (19.4 ± 10.2 mL; P< .001). The PSV in hyperthyroid postpartum thyroiditis (9.4 ± 3.4 cm/s) was significantly lower than in hypothyroid postpartum thyroiditis (14.4 ± 3.9 cm/s; P < .001) and Graves disease (19.8 ± 7.0 cm/s; P < .001). With a cutoff level of 15 cm/s, the sensitivity and specificity of the PSV as a predictor of the correct diagnosis in hyperthyroid postpartum women were 94.7% and 96.8%, respectively. A multinomial logistic regression revealed PSV and the time after delivery at which the disorders presented as independent predictors of the differentiation between hyperthyroid postpartum thyroiditis and Graves disease (P = .003; P = .022).

CONCLUSIONS

Spectral Doppler sonography was shown to be a useful and accurate method for thyroid dysfunction evaluation during the postpartum period.

The Sonographic Features of the Thyroid Gland After Treatment with Radioiodine Therapy in Patients with Graves' Disease

The aim of the study was to describe the typical sonographic features of the thyroid gland in patients with Graves' hyperthyroidism after radioiodine therapy (RIT). Thirty patients (21 female and 9 male) with a mean age of 53 y (standard deviation [SD] ± 11.3) and with previous Graves' disease who had been successfully treated with RIT were enrolled in the study. All were hypothyroid or euthyroid after treatment. The thyroid ultrasound was carried out by a single experienced operator with an 8-MHz linear transducer. Volume, vascularity, echogenicity and echotexture of the glands were noted. The presence of nodules and lymph nodes was also documented. The mean volumes of the right lobe were 2.4 mL ± 2.9 SD (0.6-14) and the left lobe were 1.8 mL ± 1.9 SD (0.4-9.1), with a mean total volume of 4.2 mL ± 4.7 SD (1.3-19.1). Of those who had a pre-treatment ultrasound (23%), the percentage reduction in volume was 87% (p < 0.05); 93% of the glands were hypovascular, with the remaining 7% showing normal vascularity. The glands were hyperechoic and of coarse echotexture. Overall, the sonographic features of the post-RIT gland included a significantly reduced mean total volume of 4.2 mL, hypovascularity, coarse echotexture and hyperechogenicity.

Screening for thyroid cancer according to French recommendations with thyroid ultrasound in newly diagnosed Graves' disease without palpable nodule is not useful

OBJECTIVE

The aim of the study was to evaluate systematic thyroid ultrasonography (US) relevance in newly diagnosed Graves' disease among patients presenting without palpable nodules.

SUBJECTS AND METHODS

We consecutively recruited 208 cases of Graves' disease without palpable nodule. All patients were screened for thyroid antibodies and underwent a thyroid US. Ultrasonically guided biopsy was proposed for the assessment of all nodules upper or equal to 10mm in diameter.

RESULTS

Two third of patients had an abnormal thyroid at palpation requiring an US. One third of patients had a normal thyroid at palpation and US was consequently unwarranted. Among all patients, US detected non-palpable nodules in 26% of cases. We found no smears suspected to be cancerous.

CONCLUSIONS

In newly diagnosed Graves' disease, the US relevance is only questionable in patients without abnormal thyroid at palpation. Ultrasonography detected non-palpable nodules and none was suspected to be cancerous. These data suggest that US is not useful in patients without abnormal thyroid at palpation. Nevertheless, the recent Thyroid Imaging-Reporting And Data System classification (TI-RADS) might change our conclusions. The TI-RADS classification indeed improves the selection of nodules lower than 10mm in diameter requiring a biopsy. Nodules lower than 10mm in diameter were not biopsied in the present study. The other US data presented herein (echogenicity, vascularisation) provide no further relevance for systematic US in newly diagnosed patients.

Ultrasound findings of subacute thyroiditis: a single institution retrospective review

BACKGROUND

High resolution ultrasonography features have also been described as having a useful supporting role in the diagnosis of subacute granulomatous thyroiditis (ST), and images are generally characterized by heterogeneous hypoechoic areas of the affected tissue with lack of flow on color Doppler US.

PURPOSE

To determine the sonographic features of subacute granulomatous thyroiditis.

MATERIAL AND METHODS

We reviewed the medical records of patients referred at the Endocrine and Metabolic Unit of our Institution between January 2010 and December 2011.

RESULTS

A total of 7520 patients were evaluated in our department between January 2010 and December 2011. Among them, 22 (0.3%) patients had a diagnosis of ST (19 women and 3 men, 45.4 ± 9.7 year; range, 33-62 years). Ultrasound examination showed bilateral ST in 64% of patients. Thyroid volume was 13.2 ± 7.7 mL, without difference if ST was unilateral (13.2 ± 7.1 mL) or bilateral (13.9 ± 8.3 mL). On grayscale US, heterogeneous diffusely or focally marked hypoechoic areas, like "lava flow", were found in all the lesions.

CONCLUSION

Our data confirm the high sensitivity of US in the diagnosis of ST: diffuse hypoechoic and confluent areas with the characteristic features like "lava flow".

Diagnosis and management of Graves disease: a global overview

Graves disease is an autoimmune disorder characterized by goitre, hyperthyroidism and, in 25% of patients, Graves ophthalmopathy. The hyperthyroidism is caused by thyroid hypertrophy and stimulation of function, resulting from interaction of anti-TSH-receptor antibodies (TRAb) with the TSH receptor on thyroid follicular cells. Measurements of serum levels of TRAb and thyroid ultrasonography represent the most important diagnostic tests for Graves disease. Management of the condition currently relies on antithyroid drugs, which mainly inhibit thyroid hormone synthesis, or ablative treatments ((131)I-radiotherapy or thyroidectomy) that remove or decrease thyroid tissue. None of these treatments targets the disease process, and patients with treated Graves disease consequently experience either a high rate of recurrence, if receiving antithyroid drugs, or lifelong hypothyroidism, after ablative therapy. Geographical differences in the use of these therapies exist, partially owing to the availability of skilled thyroid surgeons and suitable nuclear medicine units. Novel agents that might act on the disease process are currently under evaluation in preclinical or clinical studies, but evidence of their efficacy and safety is lacking.

[Colour-coded duplex-sonography versus scintigraphy. Can scintigraphy be replaced by sonography for diagnosis of functional thyroid autonomy?]

Since the development of colour coded duplex-sonography (ccds), several attempts have been made to implement this technique for diagnosis of focal lesions in the thyroid. There are controversial discussions on whether ccds might replace thyroid scintigraphy in diagnosis of hyperfunctional thyroid nodules. Aim of this study was the comparison of ccds and thyroid scintigraphy in diagnosis of functional thyroid autonomy.

PATIENTS, MATERIAL AND METHODS

192 patients with thyroid nodules > 10mm detected by conventional sonography underwent thyroid scintigraphy. Additionally, these patients were subjected to ccds of the thyroid. In total, 286 thyroid nodules were examined by scintigraphy, ccds and blood tests.

RESULTS

Thyroid scintigraphy showed 67% of thyroid nodules as hyperfunctional, 19% indifferent and 14% as hypofunctional. Mean 99mTc uptake of hyperfunctional nodules was 2.19%, of indifferent nodules 1.12% and of hypofunctional nodules 1.06% respectively. The ccds allowed perinodular measurement of flow speed (hyperfunctional: 0.23 ± 0.1 m/s; hypofunctional: 0.22 ± 0.1; indifferent: 0.21 ± 0.09), resistance index (hyperfunctional: 1.21 ± 1.16; hypofunctional: 0.62 ± 0.48; indifferent: 0.93 ± 1.02) and pulsatility index (hyperfunctional: 0.97 ± 0.45; hypofunctional: 0.84 ± 0.4; indifferent: 1.04 ± 0.6) in all nodules as well as intranodular measurement in some of the nodules (24% in hyperfunctional, 2% in indifferent and 15% in hypofunctional nodules). Statistic analysis of the obtained ccds data did not show any practically relevant correlations (p>0.05) with 99mTc uptake, basal TSH, fT3 or fT4.

CONCLUSION

Thyroid scintigraphy cannot be replaced by ccds for diagnosis of functional thyroid autonomy. Reliable diagnostics still require a combination of thyroid scintigraphy, sonography and blood tests.

Use of color Doppler ultrasonography to measure thyroid blood flow and differentiate graves' disease from painless thyroiditis

BACKGROUNDS

Color Doppler ultrasonography (CDU) has not yet been established as a method to investigate the pathogenesis of thyrotoxicosis.

OBJECTIVES

Our first objective was to determine whether the measurement of peak systolic blood-flow velocity in the superior thyroid artery (STV) and thyroid tissue blood flow (TBF) using CDU could differentiate Graves' disease (GD) from painless thyroiditis (PT). The second objective was to examine the factors mediating increased blood flow to the thyroid gland in GD.

METHODS

Recruited patients had untreated GD or PT and visited the Department of Internal Medicine (I), Osaka Medical College, between April 1, 2006 and May 31, 2010. Age, gender, blood pressure, pulse rate, thyroid-stimulating hormone, free thyroxine, tri-iodothyronine, TSH receptor antibody and thyroid volume were evaluated in patients. In addition, bilateral measurements of STV, TBF and peak systolic velocity in the common carotid artery (CCV) were also performed. TBF was quantified by calculating the ratio of blood-flow pixels to total pixels in the region of interest using sagittal section images of the thyroid gland. Receiver-operating characteristic curve analysis was performed to determine the ability of STV and TBF measurements to differentiate GD from PT.

RESULTS

For the average of STV measured on both sides, the area under the receiver-operating characteristic curve (AUC) was 0.956. For the average of TBF measured on both sides, the AUC was 0.920. At an average STV cut-off value of 43 cm/s, the sensitivity to discriminate GD from PT was 0.87 and the specificity was 1.00. At an average TBF cut-off value of 3.8%, the sensitivity was 0.71 and the specificity was 1.00. In the GD group, neither blood pressure nor pulse rate correlated with the average STV or TBF. Moreover, there was no correlation between STV and CCV or between TBF and CCV on either side. However, STV was correlated with TBF (right side: R = 0.47; left side: R = 0.52).

CONCLUSIONS

The results demonstrate that STV and TBF are useful for differentiating GD from PT. Furthermore, the increased STV and TBF found in GD are not related to hyperthyroidism-induced increases in systolic blood pressure, pulse rate or CCV.

Clinical review: Clinical utility of TSH receptor antibodies

CONTEXT

TSH receptor antibodies (TRAb) cause Graves' disease (GD) hyperthyroidism. Widely available TRAb measurement methods have been significantly improved recently. However, the role of TRAb measurement in the differential diagnosis of hyperthyroidism, the prediction of remission of GD hyperthyroidism, the prediction of fetal/neonatal thyrotoxicosis, and the clinical assessment of Graves' ophthalmopathy (GO) are controversial.

EVIDENCE ACQUISITION

We reviewed and analyzed the literature reporting primary data on the clinical use of TRAb. We focused our analyses on clinical studies analyzing third-generation TRAb assays.

EVIDENCE SYNTHESIS

The performance of TRAb in the differential diagnosis of overt hyperthyroidism is excellent, with sensitivity and specificity in the upper 90%. TRAb can accurately predict short-term relapses of hyperthyroidism after a course of antithyroid drugs but are less effective in predicting long-term relapses or remissions. Pregnancies in women with GD with negative TRAb are highly unlikely to result in fetal hyperthyroidism, whereas high titers of TRAb in pregnancy require careful fetal monitoring. GD patients with GO frequently have high TRAb levels. However, there are insufficient data to use the test to predict the clinical course of GO and response to treatment.

CONCLUSIONS

Third-generation TRAb assays are suitable in the differential diagnosis of hyperthyroidism. In GD, TRAb should be tested before deciding whether methimazole can be stopped. TRAb should be used in pregnant women with GD to assess the risk of fetal thyrotoxicosis. The use of TRAb in GO requires further studies.

Significant role of serum CRP in differentiating inflammatory from non-inflammatory causes of thyrotoxicosis

BACKGROUND

C-reactive protein (CRP), which is a marker of inflammation, has not been widely studied in inflammatory thyroid disorders particularly in sub-acute thyroiditis (SAT).

AIM

This study was aimed to find the significance of CRP level rise in patients with SAT and compare that to the rise in erythrocyte sedimentation rate (ESR), a gold standard laboratory parameter in establishing the diagnosis of SAT.

MATERIALS AND METHODS

Serum CRP levels were measured at initial presentation in 28 subjects with SAT(12 male, 16 female, age (Mean +SD) 37.96 ±8.5 years),and 19 patients with Graves' disease (2 male, 17 female, age [Mean +SD] 36.8 ±16.5 years) as controls. Erythrocyte sedimentation rate (ESR) was measured in all 28 patients with SAT by Westergrens' method. Either Tc(99) nucleotide thyroid scan or high resolution ultrasonography (HR-USG) was performed to differentiate SAT from Graves' disease.Fine needle aspiration cytology (FNAC) of thyroid was performed selected patients.

RESULTS

Serum CRP level was high in 61% of SAT patients but in none of the Graves'patients. Mean (SEM) (90%CI) serum CRP level (mg/L) was also significantly higher (P <0.0004) in the SAT group [27.55 (5.76) (15.72-39.38)], than in the Graves' group [4.09 (0.12) (3.81-4.36)]. The sensitivity of serum CRP was 73.33%, specificity 53.85%, positive predictive value (PPV) 64.71%, and negative predictive value (NPV) 63.64% as compared to the sensitivity (53.57%), specificity (15.38%), PPV (57.69 %), and NPV (13.33%) of ESR.

CONCLUSION

There is significantly higher rise in serum CRP level in patients with SAT is compared to patients with Graves' disease. It correlates well with the rise in ESR. Such findings of this pilot study highlight the scope of using serum CRP as a diagnostic marker of SAT specially in situations when it may be confused with Graves' disease, another common cause of thyrotoxicosis. It is logical to carry out studies to find a particular cut-off for serum CRP which can serve as an objective parameter for grading the inflammation in patients with SAT.

Thyrotoxicosis

Hyperthyroidism describes the sustained increase in thyroid hormone biosynthesis and secretion by a thyroid gland with increased metabolism. Although the use of radioiodine scanning serves as a useful surrogate that may help characterize the cause of thyrotoxicosis, it only indirectly addresses the underlying physiologic mechanism driving the increase in serum thyroid hormones. In this article, thyrotoxic states are divided into increased or decreased thyroid metabolic function. In addition to the diagnosis, clinical presentation, and treatment of the various causes of hyperthyroidism, a section on functional imaging and appropriate laboratory testing is included.

Color-flow doppler sonography in patients with subclinical thyroid dysfunction

OBJECTIVE

To assess the value of color-flow Doppler sonography (CFDS) in evaluating intrathyroidal blood flow and velocity in patients with subclinical thyroid dysfunction.

METHODS

In this prospective study, patients with subclinical hypothyroidism, patients with subclinical hyperthyroidism, and euthyroid patients without known thyroid autoimmune disease who served as controls were included. Subclinical thyroid dysfunction was defined as normal se-rum free thyroxine (FT4) and free triiodothyronine (FT3) in the presence of high (subclinical hypothyroidism), or low-suppressed (subclinical hyperthyroidism) serum thyrotropin (TSH) levels. Serum FT4, FT3, TSH, and antibodies to thyroid peroxidase and thyroglobulin were measured in all participants. In addition, TSH receptor antibody levels were determined in patients with subclinical hyperthyroid-ism. All participants underwent conventional sonography and CFDS. Mean peak systolic velocity (PSV) and resistive index were obtained from multiple extranodular thyroid parenchyma samplings and inferior thyroid artery measurements.

RESULTS

The study population included 27 patients with subclinical hypothyroidism, 15 patients with subclinical hyperthyroidism, and 20 euthyroid patients. Patients with subclinical hypothyroidism had significantly higher mean intrathyroidal PSV values than control patients (19.9 +/- 5.6 cm/s vs 15.7 +/- 4.4 cm/s; P = .008), whereas patients with subclinical hyperthyroidism had significantly higher mean PSV values than control patients at the inferior thyroid artery level (29.7 +/- 10.7 cm/s vs 21.9 +/- 6.8 cm/s; P = .014). Compared with control patients, a greater proportion of patients with subclinical hypothyroidism and patients with subclinical hyperthyroidism had marked CFDS patterns (78% vs 15% [P<.001] and 53% vs 15%; [P<.001], respectively). A significant association was found between positivity for thyroid autoantibodies and intense CFDS patterns. No correlation was found between TSH or thyroid hormone levels and CFDS pattern or blood flow velocity.

CONCLUSION

We have demonstrated that significantly increased thyroid blood flow velocity and vascularity are already present in patients with mild thyroid dysfunction.

The role of imaging in Graves’ disease: A cost-effectiveness analysis

According to many guidelines, scintigraphy remains the first suggested diagnostic procedure in hyperthyroid patients in spite of the widespread availability of ultrasounds. The aim of this study was to evaluate the cost-effectiveness of sonography versus scintigraphy in the management of Graves's disease, and to assess ultrasound features suggesting cancer in detecting thyroid nodules. Among 1470 hyperthyroid patients evaluated in our department from 2002 to 2005, 426 (29%) had Graves' disease: echographic and scintigraphic features were not suggestive of GD in 20/426 (4.8%) and 11/426 (2.6%) patients, respectively (p=0.763), even if one of the two procedures was almost always diagnostic. Ultrasound identified 68/426 (16%) patients with a concomitant solid lesion, while scintigraphy detected only 9/426 (2.1%) "cold" nodules (p<0.001). Thyroid cancer was diagnosed in 30/68 (47.7%) patients. Malignancy presented at ultrasound investigation blurred margins (26.7% versus 15.8%), microcalcifications (33.3% versus 28.9%) and an anteroposterior and transverse diameter ratio>or=1 (73.3% versus 71.1%); more frequently than benign nodules, but this was not statistically significant. The total cost to obtain a diagnosis by ultrasound was euro14645.34 (euro13312.5 for echography+euro1332.84 for scintigraphy in the 29 patients "negative" at echographic evaluation for GD) versus euro19922.71 by scintigraphy (euro19578.96 for scan+euro343.75 for ultrasounds in the 11 patients "negative" at scintigraphy). Our data show no difference in terms of diagnosis between sonography and scintigraphy. Indeed, scintigraphy was less sensitive in detecting nodules (often of malignant nature) than ultrasound, and, moreover, with a consequent increase of the direct cost of nodule management when scintigraphy is the first line procedure. In conclusion, according to our results, we suggest that ultrasounds with color-Doppler evaluation should be performed as first step in all hyperthyroid patients, and that scintigraphic examination should be limited only to the uncommon cases, where physician's observation, laboratory assays and/or ultrasounds are not diagnostic.

Hyperthyroidism

Thyrotoxicosis is a condition resulting from elevated levels of thyroid hormone. In this article, the authors review the presentation, diagnosis, and management of various causes of thyrotoxicosis.

Quantitative measurement of thyroid blood flow for differentiation of painless thyroiditis from Graves' disease

OBJECTIVE

Differentiation between destruction-induced thyrotoxicosis and Graves' thyrotoxicosis is important for selection of proper therapy. It is, however, often difficult to make this distinction without measurement of radioactive iodine uptake. We investigated the possibility that assessment of thyroid blood flow would allow differentiation between the two entities.

PATIENTS AND MEASUREMENTS

One hundred and fourteen untreated patients with thyrotoxicosis (56 Graves' disease, 28 painless thyroiditis, 30 subacute thyroiditis) and 25 normal controls were examined. Serum levels of freeT4 (FT4), freeT3 (FT3) and TSH were measured by chemiluminescent immunoassay, and anti-TSH receptor antibodies (TSH-binding inhibitory immunoglobulin, TBII) were measured by enzyme-linked immunosorbent assay. Thyroid volume and blood flow (TBF) were measured quantitatively by ultrasonography.

RESULTS

TBF was significantly higher in Graves' disease (mean +/- 1SD: 14.9 +/- 6.4%, P < 0.0001) than in painless thyroiditis (0.8 +/- 0.5%), subacute thyroiditis (0.9 +/- 0.7%) and in normal controls (0.8 +/- 0.5%). All patients with Graves' disease had TBF values of more than 4% and all patients with painless thyroiditis and subacute thyroiditis had TBF values less than 4%. TBF values significantly correlated with values of radioactive iodine uptake (RAIU) either at 3 h (r = 0.492, P < 0.01) or 24 h (r = 0.762, P < 0.001) within the Graves' disease and painless thyroiditis groups. There was no relationship between TBF values and thyroid volumes or values of TBII in the Graves' disease group. All patients with Graves' disease had positive TBII of 15% or more. Three of 28 patients with painless thyroiditis and one of 30 patients with subacute thyroiditis had positive TBII.

CONCLUSION

TBF was quantitatively measured by power Doppler ultrasonography and was more effective than TBII for differentiation between destruction-induced thyrotoxicosis (painless or subacute thyroiditis) and Graves' thyrotoxicosis. TBF values of less than 4% in untreated thyrotoxic patients are laboratory signals of destruction-induced thyrotoxicosis and if these are determined, the radioactive iodine uptake test can be omitted for differential diagnosis of these two types of thyrotoxicosis.