Timing of the repeat thyroid fine-needle aspiration biopsy: does early repeat biopsy change the rate of nondiagnostic or atypia of undetermined significance cytology result?

PURPOSE: To determine whether early repeat fine needle aspiration biopsy (FNA) has an effect on adequate or atypia of undetermined significance (AUS) cytology rates in thyroid nodules with inadequate or AUS result in the first FNA. METHODS: Nodules of patients who underwent repeat biopsy due to insufficient or AUS cytology between 2019-2022 were included. Data of the patients and ultrasonographic, cytological and histopathological results of the nodules were recorded. Additionally, the time between the two biopsies was noted. The first was called "initial" and the second was called "rebiopsy". Five different paired groups were formed according to the time between two consecutive biopsies; before and after 1 month, 45 days, 2 months, 3 months, and 6 months. The groups were compared in terms of adequate and AUS cytological results. RESULTS: We evaluated 1129 patients with 2187 nodules undergoing FNAB. After excluding nodules with one FNA result and/or missing data, 966 nodules of 628 patients who underwent FNA at least twice were included. Initial cytology was nondiagnostic (ND) in 665 (30.4%) and AUS in 301 (13.8%) nodules. The mean age of the patients was 52.0 ± 11.9 years, and the female sex ratio was 78.8% (n = 495). There were no differences in adequate or AUS rebiopsy results according to the different time interval groups (p > 0.05 for all). AUS result was statistically insignificantly more frequent in nodules with initially AUS nodules when rebiopsy was performed before 1 month in comparison to after 1 month (53.8%, 27.1%; p = 0.054). Accuracy of rebiopsy was also similar in the time intervals groups (p > 0.05 for all). CONCLUSION: In patients with inadequate or AUS initial biopsy, the rate of adequate or AUS cytology results at rebiopsy did not vary with the timing of repeat biopsy indicating that there may be no need to wait 1 month for a repeat biopsy. In patients with suspicious nodules, biopsy might be repeated before 1 month.

An old friend, a new insight: Calcitonin measurement in serum and aspiration needle washout fluids significantly increases the early and accurate detection of medullary thyroid cancer.

BACKGROUND: The sensitivity of cytological (CY) evaluation after fine-needle aspiration (FNA) for detecting medullary thyroid carcinoma (MTC) is a subject of controversy. The routine use of serum calcitonin (CT) in patients with thyroid nodules is not universally adopted. The authors conducted CT screening of FNA washout fluid (FNA-CT) to address the diagnostic challenges. The objective was to assess the contributions of serum CT, FNA cytology (FNA-CY), and FNA-CT to the diagnosis. METHODS: Between February 2019 and June 2022 (group 1), the authors prospectively screened the CT of patients with thyroid nodules. Both FNA-CY and FNA-CT were performed for patients with persistently elevated CT values. The sensitivity of FNA-CY, serum CT, and FNA-CT for accurate diagnosis was evaluated. Additionally, the authors retrospectively examined data from patients with thyroid nodules before CT screening (2008-2019) (group 2). They compared the characteristics of MTC patients in groups 1 and 2. RESULTS: MTC was identified in 30 patients (0.25%) in group 1 and 19 (0.07%) in group 2. A FNA-CT cutoff value of 4085.5 pg/mL detected MTC with a sensitivity of 96.8%, and a serum CT cutoff value of 28.3 pg/mL detected MTC with a sensitivity of 86.7%. In contrast, FNA-CY detected MTC with a sensitivity of 42.4%. In group 1, 18 patients (60%) with MTC were diagnosed with microcarcinoma, whereas only two patients (10.5%) in group 2 had microcarcinoma. CONCLUSIONS: This study detected MTC earlier by routinely measuring serum CT in all patients with nodular thyroid disease and performing FNA-CT in those with elevated values. FNA-CT and serum CT sensitivities were significantly higher than those of FNA-CY. This study revealed different FNA-CT cutoff values compared to other studies, emphasizing the need for determining clinic-specific cutoff values.

Serum Calcium/Phosphorus Ratio in Biochemical Screening of Primary Hyperparathyroidism.

OBJECTIVE: Primary hyperparathyroidism is a common endocrine disease and most cases are asymptomatic. Currently, in a hypercalcemic patient, the first laboratory investigation is serum primary hyperparathyroidism measurement. However, the primary hyperparathyroidism level cannot be measured in many primary healthcare centers in our country. In addition, serum calcium levels are normal in normocalcemic primary hyperparathyroidism patients, even if most centers have serum calcium levels measured. Therefore, a simple and inexpensive laboratory biochemical marker is required for the diagnosis of primary hyperparathyroidism. Recently, the calcium/phosphorus ratio has been proposed as a suitable tool for diagnosing primary hyperparathyroidism. This study aimed to investigate the diagnostic value of serum calcium/phosphorus ratio in primary hyperparathyroidism screening. METHODS: A total of 462 patients followed in our clinic with a diagnosis of primary hyperparathyroidism were reviewed in this retrospective study. Out of these patients, 148 with normal levels of serum parathyroid hormone, calcium, and phosphorus were selected as the control group. Serum calcium, corrected calcium, phosphorus, albumin, parathyroid hormone, 25-hydroxyvitamin D, and creatinine were evaluated. The diagnostic accuracy of the calcium/phosphorus ratio was investigated using receiver operating characteristic curve analysis. RESULTS: There were 404 (87.4%) females and 58 (12.6%) males in the primary hyperparathyroidism group. Calcium, parathyroid hormone, and calcium/phosphorus ratio were significantly higher in primary hyperparathyroidism than in controls (p<0.001 for each). Receiver operating characteristic curve analyses identified a cutoff value of 2.59 (3.35 if calcium and phosphorus are measured in mg/dL) for the calcium/phosphorus ratio, with a sensitivity of 90.5% and specificity of 93.2% (p<0.001). CONCLUSION: The calcium/phosphorus ratio is a simple and inexpensive method for primary hyperparathyroidism screening when a cutoff value of 2.59 is used.

Thicknesses of the retinal layers in patients with Graves' disease with or without orbitopathy.

PURPOSE: Graves' orbitopathy (GO) is an inflammatory process that may involve the ocular surface, orbital fat, extraocular muscles, and optic nerves in patients with Graves' disease (GD). We aimed to compare thicknesses of retinal layers in patients with GD with and without GO. METHODS: One hundred seven patients with GD [23 with GO (Group 1), 84 without GO (Group 2)] and eighteen volunteers (Group 3) were enrolled. The spectral-domain optical coherence tomography (SD-OCT) was used for ophthalmologic evaluation. Seven retinal layers including retinal nerve fibre layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), retinal pigment epithelium (RPE) were assessed. The thicknesses of layers were compared in groups. RESULTS: The median GCL thickness values in groups 1, 2, and 3 were 14 µm, 15 µm, and 17.5 µm, respectively (p = 0.02). The median IPL thickness was 20 µm in group 1, 21 µm in group 2, and 22 µm in group 3 (p = 0.038). The median RPE thickness values in groups 1, 2, and 3 were 16 µm, 17 µm, and 18.5 µm, respectively (p = 0.001). GCL in group 1 was thinner than in group 3 (p = 0.02), while similar in groups 2 and 3 (p = 0.06). IPL in group 1 was thinner than in group 3 (p = 0.035), while similar in groups 2 and 3 (p = 0.13). RPE in groups 1 and 2 was thinner than in group 3 (p = 0.009, p = 0.001, respectively), while it was similar in groups 1 and 2 (p = 0.93). RNLF, INL, OPL, ONL were similar in all three (p > 0.05 for each). CONCLUSION: Ganglion cell layer and IPL were thinner in patients with GO than in healthy controls, while both were similar in patients without GO and healthy controls. RPE was thinner in all Graves patients than in healthy controls. Early detection of changes in retinal layers of GD may guide the physician to prevent significant vision problems.

Serum Calcium/Phosphorus Ratio in Biochemical Screening of Primary Hyperparathyroidism

SUMMARY OBJECTIVE: Primary hyperparathyroidism is a common endocrine disease and most cases are asymptomatic. Currently, in a hypercalcemic patient, the first laboratory investigation is serum primary hyperparathyroidism measurement. However, the primary hyperparathyroidism level cannot be measured in many primary healthcare centers in our country. In addition, serum calcium levels are normal in normocalcemic primary hyperparathyroidism patients, even if most centers have serum calcium levels measured. Therefore, a simple and inexpensive laboratory biochemical marker is required for the diagnosis of primary hyperparathyroidism. Recently, the calcium/phosphorus ratio has been proposed as a suitable tool for diagnosing primary hyperparathyroidism. This study aimed to investigate the diagnostic value of serum calcium/phosphorus ratio in primary hyperparathyroidism screening. METHODS: A total of 462 patients followed in our clinic with a diagnosis of primary hyperparathyroidism were reviewed in this retrospective study. Out of these patients, 148 with normal levels of serum parathyroid hormone, calcium, and phosphorus were selected as the control group. Serum calcium, corrected calcium, phosphorus, albumin, parathyroid hormone, 25-hydroxyvitamin D, and creatinine were evaluated. The diagnostic accuracy of the calcium/phosphorus ratio was investigated using receiver operating characteristic curve analysis. RESULTS: There were 404 (87.4%) females and 58 (12.6%) males in the primary hyperparathyroidism group. Calcium, parathyroid hormone, and calcium/phosphorus ratio were significantly higher in primary hyperparathyroidism than in controls (p<0.001 for each). Receiver operating characteristic curve analyses identified a cutoff value of 2.59 (3.35 if calcium and phosphorus are measured in mg/dL) for the calcium/phosphorus ratio, with a sensitivity of 90.5% and specificity of 93.2% (p<0.001). CONCLUSION: The calcium/phosphorus ratio is a simple and inexpensive method for primary hyperparathyroidism screening when a cutoff value of 2.59 is used.

Retinal layers in prolactinoma patients: a spectral-domain optical coherence tomography study.

PURPOSE: Prolactinoma is a type of pituitary tumour that produces an excessive amount of the hormone prolactin. It is the most common type of hormonally-active pituitary tumour. These tumours can cause ocular complications such as vision loss and visual fields (VF) defect. In this study, we aimed to evaluate the thickness of chorioretinal layers in patients with prolactinoma. METHODS: We enrolled 63 eyes of 32 prolactinoma patients and 36 eyes of 18 age and gender-matched healthy controls. All participants underwent complete hormonal and ophthalmological examination, including spectral-domain optical coherence tomography (SD-OCT) and VF test.The complete biochemical response was defined as serum PRL concentration ≤ 20 ng/mL at the time of evaluation.The seven layers were retinal nerve fibre layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), and retinal pigment epithelium (RPE). The results of prolactinoma patients were compared with the control group. RESULTS: The mean RNFL, GCL, IPL, INL, ONL, and RPE were thinner in prolactinoma patients than the control group (p < 0.05) while OPL was similar between groups (p > 0.05).None of the patients had VF defect.The thickness of retinal layers was similar in patients with and without complete biochemical response (p > 0.05). CONCLUSION: To our knowledge, this is the first study that evaluates the thickness of chorioretinal layers in patients with prolactinoma.Most of the layers were thinner than the control group.Therefore, detailed eye assessment should be a routine component of the follow-up visits of prolactinoma patients and further studies related to this condition are required.

Effect of Ramadan Fasting on Thyroid Hormone Levels in Patients on Levothyroxine Treatment.

OBJECTIVE: To evaluate the changes in thyroid functions in Ramadan, and compare late evening and pre-seheri use of levothyroxine in patients with hypothyroidism. STUDY DESIGN: Cross-sectional study. PLACE AND DURATION OF STUDY: Department of Endocrinology, Ankara Ataturk Education and Research Hospital and Ankara Yildirim Beyazit University, Turkey, from May to June 2018. METHODOLOGY: Patients who were on levothyroxine treatment and having normal thyroid functions were recruited for the study in the last one week before Ramadan. Patients were offered to take levothyroxine at 22.30-23.00 pm before sleep or between 01:30-03:00 am at least 30 min pre-seheri. RESULTS: There were 53 (85.5%) female and 9 (14.5%) male patients. Basal thyrotrophin (TSH) was 2.02 µIU/mL (0.27-4.14) and insignificantly increased at the end of Ramadan [2.18 µIU/mL (0.04-19.69), p=0.167]. Free-triiodothyronine (fT3) decreased while free-thyroxine (fT4) increased (p<0.001 for both). Eighteen patients preferred to take levothyroxine in late evening and 44 preferred to take at pre-seheri. There were insignificant increases in TSH in both groups (p=0.401 and p=0.276, respectively). At the end of Ramadan, TSH increased in 39 (63.9%), decreased in 22 (36.1%), and did not change in one patient. CONCLUSION: Increase in TSH was not significant after Ramadan. While there was an insignificant increase in median TSH, about one-third of patients had lower TSH, indicating for the need to evaluate every patient individually and follow closely during Ramadan. Clinical studies with larger sample sizes will be helpful to determine the optimal time for levothyroxine use during Ramadan. Key Words: Thyroid functions, Ramadan fasting, Hypothyroidism, Levotyhroxine.

Can Repeat Biopsies Change the Prognoses of AUS/FLUS Nodule?

OBJECTIVE: Experience with atypia of undetermined significance/follicular lesions of undetermined significance (AUS/FLUS) showed that this category exhibited a marked variability in incidence and malignant outcome in resection specimens. We aimed to determine the utility of repeated fine-needle aspiration biopsies (FNABs) and ultrasonography to determine the malignancy rate in AUS/FLUS nodules. METHODS: 23,587 nodules were biopsied, and 1,288 had at least one AUS/FLUS cytology. Ultrasonographic features including solid hypoechoic status, irregular margins, microcalcifications, nodule taller than wider, or an extrathyroidal extension were also recorded. Nodules for which only 1 FNAB revealed AUS/FLUS cytology were termed Group 1; nodules that underwent 2, 3, and 4 FNABs were termed Groups 2, 3 and 4, respectively. We compared these groups according to malignancy rates. RESULTS: 576 of nodules underwent only 1 FNAB (Group 1); 505, 174, and 33 underwent 2 (Group 2), 3 (Group 3), and 4 FNABs (Group 4), respectively. Fifty-six (30.6%), 45 (27.3%), 18 (30%), and 5 (33.3%) of Groups 1-4 were malignant, respectively. The risk of malignancy was similar in each group (p > 0.05). Suspicious ultrasonographic features were encountered in malignant nodules more than benign nodules (p < 0.05, for each). CONCLUSION: Repeat biopsy of AUS/FLUS nodules did not enhance the identification of malignancy. Ultrasonographic features may be a better guide for the decision of either surveillance or diagnostic surgery.

Ultrasound elastography score and strain index in different parathyroid lesions.

BACKGROUND: Despite significant improvement in imaging quality and advanced scientific knowledge, it may still sometimes be difficult to distinguish different parathyroid lesions. The aims of this prospective study were to evaluate parathyroid lesions with ultrasound elastography and to determine whether strain index can help to differentiate parathyroid lesions. METHODS: Patients with biochemically confirmed hyperparathyroidism and localised parathyroid lesions in ultrasonography were included. All patients underwent B-mode US and USE examination. Ultrasound elastography scores and strain index of lesions were determined. Strain index was defined as the ratio of strain of the thyroid parenchyma to the strain of the parathyroid lesion. RESULTS: Data of 245 lesions of 230 patients were analysed. Histopathologically, there were 202 (82.45%) parathyroid adenomas, 26 (10.61%) atypical parathyroid adenomas, and 17 (6.94%) cases of parathyroid hyperplasia. Median serum Ca was significantly higher in atypical parathyroid adenoma patients than parathyroid hyperplasia patients (P = 0.019) and median PTH was significantly higher in APA compared to PA patients (P < 0.001). In 221 (90.2%) of the parathyroid lesions, USE score was 1 or 2. The median SI of atypical parathyroid adenomas was significantly higher than parathyroid adenomas and hyperplasia lesions (1.5 (0.56-4.86), 1.01 (0.21-8.43) and 0.91 (0.26-2.02), respectively, P = 0.003). CONCLUSION: Our study revealed that SI of parathyroid lesions as well as serum calcium, parathyroid hormone levels, and B-mode US features may help to predict the atypical parathyroid adenoma. Ultrasound elastography can be used to differentiate among parathyroid lesions and guide a surgical approach.

Is thyroid nodule volume predictive for malignancy?

ABSTRACT Objective: We aimed to determine the roles of preoperative thyroid nodule diameter and volume in the prediction of malignancy. Subjects and methods: The medical records of patients who underwent thyroidectomy between January 2007 and December 2014 were reviewed. The nodule diameters were grouped as < 1 cm, 1-1.9 cm, 2-3.9 cm and ≥ 4 cm, and volume was grouped as > 5 cm3, 5-9.9 cm3 and > 10 cm3. ROC (Receiver Operating Characteristic) curve analysis was performed to find the optimal cutoff value of diameter and volume that can predict malignancy. Results: There were 5561 thyroid nodules in 2463 patients. Five hundred and forty (9.7%) nodules were < 1 cm, 2,413 (43.4%) were 1-1.9 cm, 1,600 (28.8%) were 2-3.9 cm and 1,008 (18.1%) were ≥ 4 cm. Malignancy rates were 25.6%,10.6%, 9.7% and 8.5% in nodules < 1 cm, 1-1.9 cm, 2-3.9 cm and ≥ 4 cm, respectively. When classified according to volume, 3,664 (65.9%) nodules were < 5 cm3, 594 (10.7%) were 5-9.9 cm3 and 1,303 (23.4%) were ≥ 10 cm3. The malignancy rates were 12.7%, 11.4% and 7.8% for the nodules < 5 cm3, 5-9.9 cm3 and ≥ 10 cm3, respectively (p < 0.001). In ROC curve analysis, an optimal cutoff value for diameter or volume that can predict malignancy in all thyroid nodules or nodules ≥ 4 cm could not be determined. Conclusion: In this surgical series, malignancy risk did not increase with increasing nodule diameter or volume. Although the volume of malignant nodules ≥ 4 cm was higher than that of benign nodules ≥ 4 cm, there was no optimal cutoff value. The diameter or volume of the nodule cannot be used to predict malignancy or decide on surgical resection.

Is thyroid nodule volume predictive for malignancy?

OBJECTIVE: We aimed to determine the roles of preoperative thyroid nodule diameter and volume in the prediction of malignancy. SUBJECTS AND METHODS: The medical records of patients who underwent thyroidectomy between January 2007 and December 2014 were reviewed. The nodule diameters were grouped as < 1 cm, 1-1.9 cm, 2-3.9 cm and ≥ 4 cm, and volume was grouped as > 5 cm3, 5-9.9 cm3 and > 10 cm3. ROC (Receiver Operating Characteristic) curve analysis was performed to find the optimal cutoff value of diameter and volume that can predict malignancy. RESULTS: There were 5561 thyroid nodules in 2463 patients. Five hundred and forty (9.7%) nodules were < 1 cm, 2,413 (43.4%) were 1-1.9 cm, 1,600 (28.8%) were 2-3.9 cm and 1,008 (18.1%) were ≥ 4 cm. Malignancy rates were 25.6%,10.6%, 9.7% and 8.5% in nodules < 1 cm, 1-1.9 cm, 2-3.9 cm and ≥ 4 cm, respectively. When classified according to volume, 3,664 (65.9%) nodules were < 5 cm3, 594 (10.7%) were 5-9.9 cm3 and 1,303 (23.4%) were ≥ 10 cm3. The malignancy rates were 12.7%, 11.4% and 7.8% for the nodules < 5 cm3, 5-9.9 cm3 and ≥ 10 cm3, respectively (p < 0.001). In ROC curve analysis, an optimal cutoff value for diameter or volume that can predict malignancy in all thyroid nodules or nodules ≥ 4 cm could not be determined. CONCLUSION: In this surgical series, malignancy risk did not increase with increasing nodule diameter or volume. Although the volume of malignant nodules ≥ 4 cm was higher than that of benign nodules ≥ 4 cm, there was no optimal cutoff value. The diameter or volume of the nodule cannot be used to predict malignancy or decide on surgical resection.

Comparative analysis of diagnostic adequacy rate between aspiration and nonaspiration techniques of fine-needle cytology in patients with thyroid cancer and ultrasonographically suspicious cervical lymph nodes.

BACKGROUND: We aimed to compare nonaspiration (NAS) and aspiration (AS) techniques in the evaluation of fine-needle cytology of lymph node (FNC-LN) in terms of diagnostic adequacy of cytologic material. METHODS: One hundred and twenty-three superficial cervical LNs in 75 patients who underwent NAS and AS-FNC-LN in the same visit were evaluated. Cytological results were categorized as diagnostic and nondiagnostic. RESULTS: The rates of malignancy were 13.8% in AS versus 16.3% in NAS technique, whereas nondiagnostic cytology was detected in 43.1% and 25.2%, respectively (P = .549 and P < .01). CONCLUSIONS: The diagnostic adequacy rate in NAS-FNC-LN was significantly higher than AS-FNC-LN. However, NAS technique seems to be more simple and comfortable. We suggest both NAS and AS-FNC-LN in cytologic evaluation of suspicious cervical LNs until the diagnostic accuracy is determined with prospective studies.

SHOULD MULTIFOCAL PAPILLARY THYROID CARCINOMAS CLASSIFIED AS T1A WITH A TUMOR DIAMETER SUM OF 1 TO 2 CENTIMETERS BE RECLASSIFIED AS T1B?

OBJECTIVE: Considering the diameter of the largest tumor while determining T stage in multifocal papillary thyroid microcarcinomas (PTMCs) might cause underestimation of tumoral stage. We aimed to investigate the effect of total tumor diameter (TTD) on tumor node metastasis (TNM) classification in multifocal T1a PTMCs. METHODS: T1 tumors were grouped as T1a or T1b according to 7th TNM edition. For patients with multifocal T1a, TTD (the sum of the maximal diameter of each focus) was calculated, and these patients were further subgrouped as TTD ≤1 cm or TTD 1 to 2 cm. RESULTS: There were 724 patients with T1 tumors. Multifocality was observed in 150 (28.5%) of 527 patients with T1a and 84 (42.6%) of 197 patients with T1b tumors (P<.001). Lymph node metastasis (LNM), thyroid capsule invasion, and lymphovascular invasion were significantly higher in T1b compared to T1a (P<.001, P<.001, and P = .015, respectively). There were 8 (1.5%) patients with persistence but not any with recurrence in the T1a group. Persistence and recurrence were observed in 3 (1.5%) and 5 (2.5%) patients in the T1b group, respectively. Among 150 T1a patients with multifocal tumors, TTD was ≤1 cm in 89 (59.3%) and 1 to 2 cm in 61 (40.7%) patients. Number of tumor foci, LNM, and thyroid capsule invasion were significantly higher in multifocal T1a patients with TTD 1 to 2 cm compared to with TTD ≤1 cm (P<.001, P = .032, P = .014, respectively). CONCLUSION: TTD might be used as a parameter to determine patients at higher risk for persistence, and T1a multifocal PTMCs with TTD 1 to 2 cm can be reclassified as T1b. ABBREVIATIONS: ETE = extrathyroidal extension LNM = lymph node metastasis PTC = papillary thyroid carcinoma PTMC = papillary thyroid microcarcinoma RAI = radioactive iodine TNM = tumor, node, metastasis TTD = total tumor diameter.

Evaluation of postural parathyroid hormone change in patients with primary hyperparathyroidism.

Purpose. In the present study, we aimed to investigate postural change of PTH in normal individuals and in patients with primary hyperparathyroidism (PHPT). Methods. Twenty-two patients with PHPT and nine healthy controls were enrolled. Following 12 h of fast, patients stayed in recumbent position for an hour and PTH and total Ca measurements were performed at the 45th and 60th minutes of resting. Afterwards, the patients resumed an upright posture for an hour and again blood samples were taken at the 45th and 60th minutes of standing. Results. In the PHPT group, mean PTH was calculated as 153.9 pg/mL in the recumbent position while it was 206.3 during upright position (Δ change was 47.7) (P < 0.001). In the control group mean serum PTH was measured as 41.2 pg/mL in the recumbent position while it was 44.8 pg/mL in the upright position (Δ change was 1.7) (P = 0.11). In both groups, serum Ca was higher in the upright position compared to the recumbent position (P < 0.001). Conclusion. Postural change of serum PTH is significant only in PHPT group. Postural PTH test may give a clue to the clinician when the diagnosis of PHPT is equivocal.

Diagnostic value of endoscopic ultrasonography for preoperative localization of parathyroid adenomas.

The most common cause of primary hyperparathyroidism (PHPT) is a single, sporadic parathyroid adenoma. Ultrasonography (US) and (99m)Technetium methoxyisobutylisonitrile ((99m)Tc-MIBI) scintigraphy are the imaging methods most widely used to localize parathyroid adenomas. The purpose of the present study was to determine the diagnostic value and accuracy of endoscopic ultrasonography (EUS) for localizing parathyroid adenoma compared with those of US and (99m)Tc-MIBI scintigraphy. Forty-seven patients with a PHPT diagnosis and who were recommended for surgery were enrolled in this study. An endoscopist who was blinded to the previous US and (99m)Tc-MIBI scintigraphy results performed the EUS in each patient. Thirty-nine female and eight male patients with PHPT were evaluated. The presence of adenoma was confirmed by subsequent postsurgical pathology results. One case was excluded because the histopathological evaluation was compatible with a lymph node, although the lesion was detected using three different imaging modalities preoperatively. The locations of the parathyroid adenomas were correctly documented by US in 39 patients (84.7 %) by (99m)Tc-MIBI scintigraphy in 35 (76.0 %), and by EUS in 44 (95.6 %) of 46 patients. EUS located all 31 adenomas detected previously with US and (99m)Tc-MIBI scintigraphy. EUS also successfully located three adenomas that could not be identified by US and (99m)Tc-MIBI scintigraphy. The positive predictive value and diagnostic accuracy of EUS, US, and (99m)Tc-MIBI were 97.7, 97.7, and 95.6 %; 88.6, 97.5, and 86.9 %; and 77.7, 97.2, 76.0 %, respectively. EUS was preferred as the second step imaging tool for detecting parathyroid adenomas that could not be localized by US and (99m)Tc-MIBI scintigraphy.