Association between DIO2 Thr92Ala polymorphism and hypertension in patients with hypothyroidism: Korean Genome and Epidemiology Study

Background/Aims@#Recent evidence has identified the significance of type 2 iodothyronine deiodinase (DIO2) in various diseases. However, the role of DIO2 polymorphism in metabolic parameters in patients with hypothyroidism is not fully understood. @*Methods@#We assessed the polymorphism of the DIO2 gene and various clinical parameters in 118 patients who were diagnosed with hypothyroidism from the Ansan-Anseong cohort of the Korean Genome and Epidemiology Study. Furthermore, we systematically analyzed Genotype-Tissue Expression (GTEx) data. @*Results@#A total of 118 participants with hypothyroidism were recruited; 32 (27.1%) were homozygous for the Thr allele, 86 (73.9%) were homozygous for the Ala allele or heterozygous. Patients with hypothyroidism with DIO2 polymorphism without hypertension at baseline had higher incidence of hypertension compared to patients without DIO2 polymorphism. Analysis of the GTEx database revealed that elevation of DIO2 expression is associated with enhancement of genes involved in blood vessel regulation and angiogenesis. @*Conclusions@#Commonly inherited variation in the DIO2 gene is associated with high blood pressure and prevalence of hypertension in patients with hypothyroidism. Our results suggest that genetic variation in the hypothalamic-pituitary-thyroid pathway in influencing susceptibility to hypertension.

Effectiveness and Usefulness of Bone Turnover Marker in Osteoporosis Patients: A Multicenter Study in Korea

Background@#This study aimed to investigate real-world data of C-terminal telopeptide (CTX), propeptide of type I collagen (P1NP), and osteocalcin through present multicenter clinical study, and retrospectively analyze the usefulness of bone turnover markers (BTMs) in Koreans. @*Methods@#The study focused on pre- and post-menopausal patients diagnosed with osteoporosis and excluded patients without certain test results or with test intervals of over 1 year. The demographic data and 3 BTMs (CTX, P1NP, and osteocalcin) were collected. The patients were classified by demographic characteristics and the BTM concentrations were analyzed by the group. @*Results@#Among women with no history of fractures, the levels of P1NP (N=2,100) were 43.544±36.902, CTX (N=1,855) were 0.373 ±0.927, and osteocalcin (N=219) were 10.81 ±20.631. Among men with no history of fractures, the levels of P1NP (N=221) were 48.498±52.892, CTX (N=201) were 0.370±0.351, and osteocalcin (N=15) were 7.868 ±10.674. Treatment with teriparatide increased the P1NP levels after 3 months in both men and women, with a 50% increase observed in women. Similarly, treatment with denosumab decreased the CTX levels after 3 months in both men and women, with a reduction of 50% observed in women. @*Conclusions@#The results of this study can contribute to the accurate assessment of bone replacement status in Koreans. We also provide the P1NP level in the Korean population for future comparative studies with other populations.

Metabolite Changes during the Transition from Hyperthyroidism to Euthyroidism in Patients with Graves’ Disease

Background@#An excess of thyroid hormones in Graves’ disease (GD) has profound effects on systemic energy metabolism that are currently partially understood. In this study, we aimed to provide a comprehensive understanding of the metabolite changes that occur when patients with GD transition from hyperthyroidism to euthyroidism with methimazole treatment. @*Methods@#Eighteen patients (mean age, 38.6±14.7 years; 66.7% female) with newly diagnosed or relapsed GD attending the endocrinology outpatient clinics in a single institution were recruited between January 2019 and July 2020. All subjects were treated with methimazole to achieve euthyroidism. We explored metabolomics by performing liquid chromatography-mass spectrometry analysis of plasma samples of these patients and then performed multivariate statistical analysis of the metabolomics data. @*Results@#Two hundred metabolites were measured before and after 12 weeks of methimazole treatment in patients with GD. The levels of 61 metabolites, including palmitic acid (C16:0) and oleic acid (C18:1), were elevated in methimazole-naïve patients with GD, and these levels were decreased by methimazole treatment. The levels of another 15 metabolites, including glycine and creatinine, were increased after recovery of euthyroidism upon methimazole treatment in patients with GD. Pathway analysis of metabolomics data showed that hyperthyroidism was closely related to aminoacyl-transfer ribonucleic acid biosynthesis and branched-chain amino acid biosynthesis pathways. @*Conclusion@#In this study, significant variations of plasma metabolomic patterns that occur during the transition from hyperthyroidism to euthyroidism were detected in patients with GD via untargeted metabolomics analysis.

Expression of LONP1 Is High in Visceral Adipose Tissue in Obesity, and Is Associated with Glucose and Lipid Metabolism

Background@#The nature and role of the mitochondrial stress response in adipose tissue in relation to obesity are not yet known. To determine whether the mitochondrial unfolded protein response (UPRmt) in adipose tissue is associated with obesity in humans and rodents. @*Methods@#Visceral adipose tissue (VAT) was obtained from 48 normoglycemic women who underwent surgery. Expression levels of mRNA and proteins were measured for mitochondrial chaperones, intrinsic proteases, and components of electron-transport chains. Furthermore, we systematically analyzed metabolic phenotypes with a large panel of isogenic BXD inbred mouse strains and Genotype-Tissue Expression (GTEx) data. @*Results@#In VAT, expression of mitochondrial chaperones and intrinsic proteases localized in inner and outer mitochondrial membranes was not associated with body mass index (BMI), except for the Lon protease homolog, mitochondrial, and the corresponding gene LONP1, which showed high-level expression in the VAT of overweight or obese individuals. Expression of LONP1 in VAT positively correlated with BMI. Analysis of the GTEx database revealed that elevation of LONP1 expression is associated with enhancement of genes involved in glucose and lipid metabolism in VAT. Mice with higher Lonp1 expression in adipose tissue had better systemic glucose metabolism than mice with lower Lonp1 expression. @*Conclusion@#Expression of mitochondrial LONP1, which is involved in the mitochondrial quality control stress response, was elevated in the VAT of obese individuals. In a bioinformatics analysis, high LONP1 expression in VAT was associated with enhanced glucose and lipid metabolism.

Expression of LONP1 Is High in Visceral Adipose Tissue in Obesity, and Is Associated with Glucose and Lipid Metabolism

Background@#The nature and role of the mitochondrial stress response in adipose tissue in relation to obesity are not yet known. To determine whether the mitochondrial unfolded protein response (UPRmt) in adipose tissue is associated with obesity in humans and rodents. @*Methods@#Visceral adipose tissue (VAT) was obtained from 48 normoglycemic women who underwent surgery. Expression levels of mRNA and proteins were measured for mitochondrial chaperones, intrinsic proteases, and components of electron-transport chains. Furthermore, we systematically analyzed metabolic phenotypes with a large panel of isogenic BXD inbred mouse strains and Genotype-Tissue Expression (GTEx) data. @*Results@#In VAT, expression of mitochondrial chaperones and intrinsic proteases localized in inner and outer mitochondrial membranes was not associated with body mass index (BMI), except for the Lon protease homolog, mitochondrial, and the corresponding gene LONP1, which showed high-level expression in the VAT of overweight or obese individuals. Expression of LONP1 in VAT positively correlated with BMI. Analysis of the GTEx database revealed that elevation of LONP1 expression is associated with enhancement of genes involved in glucose and lipid metabolism in VAT. Mice with higher Lonp1 expression in adipose tissue had better systemic glucose metabolism than mice with lower Lonp1 expression. @*Conclusion@#Expression of mitochondrial LONP1, which is involved in the mitochondrial quality control stress response, was elevated in the VAT of obese individuals. In a bioinformatics analysis, high LONP1 expression in VAT was associated with enhanced glucose and lipid metabolism.

The Significance of Transcriptomic Signatures in the Multifocal Papillary Thyroid Carcinoma: Two mRNA Expression Patterns with Distinctive Clinical Behavior from The Cancer Genome Atlas (TCGA) Database

Background and Objectives@#The association between multifocal papillary thyroid carcinoma (PTC) and tumor aggressiveness remains controversial. The aim of study is to evaluate molecular subtypes of multifocal PTCs using multiplatform genomic analysis. @*Materials and Methods@#Statistical analysis and genomic analysis were performed for gene expression data and clinical data of multifocal PTCs in The Cancer Genome Atlas data. Clinicopathologic findings, recurrence-free survival (RFS), copy number alteration and somatic mutation status in patients in relation to molecular subtypes were analyzed. @*Results@#Multiplatform genomic analysis revealed that multifocal PTCs (n=226) were divided into two distinct molecular subgroups. Participants in cluster 2 showed significantly increased risk of extrathyroidal extension, lymph node metastasis, and BRAFV600E mutation compared to patients in cluster 1. To exclude the effect of BRAF mutation and RAS mutation on tumor aggressiveness, we compared clinical parameters between two clusters in patients without BRAF or RAS mutation. Cluster 2 showed significantly higher risk of lymph node metastasis compared to cluster 1. @*Conclusion@#Multifocal PTC has two distinct molecular subtypes with distinctive clinical behaviors. Our data suggested the clinical implications of the transcriptomic signature to predict clinical outcomes of multifocal PTC.

Clinical Implication of World Health Organization Classification in Patients with Follicular Thyroid Carcinoma in South Korea: A Multicenter Cohort Study

Background@#The study aimed to compare the prognostic value of the 4th edition of World Health Organization classification (WHO-2017) with the previous WHO classification (WHO-2004) for follicular thyroid carcinoma (FTC). @*Methods@#This multicenter retrospective cohort study included 318 patients with FTC from five tertiary centers who underwent thyroid surgery between 1996 and 2009. We evaluated the prognosis of patients with minimally invasive (MI), encapsulated angioinvasive (EA), and widely invasive (WI) FTC according to WHO-2017. Further, we evaluated the proportion of variation explained (PVE) and Harrell’s C-index to compare the predictability of disease-free survival (DFS) and disease-specific survival (DSS). @*Results@#In total, 227, 58, and 33 patients had MI-, EA-, and WI-FTC, respectively. During a median follow-up of 10.6 years, 46 (14.5%) patients had disease recurrence and 20 (6.3%) patients died from FTC. The 10-year DFS rates of patients with MI-, EA-, and WI-FTC were 91.1%, 78.2%, and 54.9%, respectively (P<0.001, PVE=7.1%, C-index=0.649). The corresponding 10-year DSS rates were 95.9%, 93.5%, and 73.5%, respectively (P<0.001, PVE=2.6%, C-index=0.624). The PVE and C-index values were higher using WHO-2017 than using WHO-2004 for the prediction of DFS, but not for DSS. In multivariate analysis, older age (P=0.02), gross extrathyroidal extension (ETE) (P=0.003), and distant metastasis (P<0.001) were independent risk factors for DSS. @*Conclusion@#WHO-2017 improves the predictability of DFS, but not DSS, in patients with FTC. Distant metastasis, gross ETE and older age (≥55 years) were independent risk factors for DSS.

Modification of the Tumor-Node-Metastasis Staging System for Differentiated Thyroid Carcinoma by Considering Extra-Thyroidal Extension and Lateral Cervical Lymph Node Metastasis

BACKGROUND: Concerns have arisen about the classification of extra-thyroidal extension (ETE) and lateral cervical lymph node metastasis (N1b) in the 8th edition of the tumor-node-metastasis staging system (TNM-8). This study evaluated the prognostic validity of a modified-TNM staging system, focusing on ETE and N1b, in differentiated thyroid carcinoma (DTC) patients.METHODS: This multicenter retrospective cohort study included 4,878 DTC patients from five tertiary hospitals. In the modified-TNM, T3b in TNM-8 was down-staged to T2, and stage II was subdivided into stages IIA and IIB. Older patients with N1b were reclassified as stage IIB.RESULTS: The modified-TNM resulted in staging migration in 540 patients (11%) classified as stage II according to the TNM-8, with 75 (14%), 381 (71%), and 84 patients (16%) classified as stages I, IIA, and IIB, respectively. The 10-year disease-specific survival (DSS) rates in patients classified as stages I, II, III, and IV by TNM-8 were 99.8%, 95.9%, 81.0%, and 41.6%, respectively. The DSS rates of patients classified as stages I, IIA, IIB, III, and IV according to the modified-TNM were 99.8%, 96.4%, 93.3%, 81.0%, and 41.6%, respectively. DSS curves between stages on TNM-8 (P<0.001) and modified-TNM (P<0.001) differed significantly, but the modified-TNM discriminated better than TNM-8. The proportions of variation explained values of TNM-8 and modified-TNM were 6.3% and 6.5%, respectively.CONCLUSION: Modification of the TNM staging system focusing on ETE and N1b could improve the prediction of DSS in patients with DTC. Further researches are needed to validate the prognostic accuracy of this modified-TNM staging system.

Implications of Mitochondrial Unfolded Protein Response and Mitokines: A Perspective on Fatty Liver Diseases

The signaling network of the mitochondrial unfolded protein response (UPR(mt)) and mitohormesis is a retrograde signaling pathway through which mitochondria-to-nucleus communication occurs in organisms. Recently, it has been shown that the UPR(mt) is closely associated with metabolic disorders and conditions involving insulin resistance, such as alcoholic and non-alcoholic fatty liver and fibrotic liver disease. Scientific efforts to understand the UPR(mt) and mitohormesis, as well as to establish the mitochondrial proteome, have established the importance of mitochondrial quality control in the development and progression of metabolic liver diseases, including non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). In this review, we integrate and discuss the recent data from the literature on the UPR(mt) and mitohormesis in metabolic liver diseases, including NAFLD/NASH and fibrosis.

Serum R-Spondin 1 Is a New Surrogate Marker for Obesity and Insulin Resistance

BACKGROUND: Recent in vivo studies indicated that R-spondin 1 (RSPO1) regulates food intake and increases insulin secretion, but its role in humans remains unknown. This study investigated the association between serum levels of RSPO1 and diverse metabolic parameters in humans. METHODS: The study population consisted of 43 subjects with newly diagnosed diabetes mellitus, and 79 non-diabetic participants. Serum levels of RSPO1 were measured using the enzyme-linked immunosorbent assay. The relationships between circulating RSPO1 and diverse metabolic parameters were analyzed. RESULTS: Circulating RSPO1 levels increased to a greater extent in the obese group than in the lean group. Moreover, serum levels of RSPO1 were higher in the insulin-resistant group than in the insulin-sensitive group. Serum levels of RSPO1 were significantly correlated with a range of metabolic parameters including body mass index, fasting C-peptide, homeostasis model assessment of insulin resistance index, and lipid profile. Moreover, levels were significantly associated with insulin resistance and obesity in non-diabetic subjects. CONCLUSION: This study demonstrated the association between serum levels of RSPO1 and a range of metabolic parameters in humans. Serum levels of RSPO1 are significantly related to obesity and insulin resistance, although the precise mechanisms remain unknown.

Genetic Analysis of CLCN7 in an Old Female Patient with Type II Autosomal Dominant Osteopetrosis

BACKGROUND: Type II autosomal dominant osteopetrosis (ADO II) is a rare genetically heterogeneous disorder characterized by osteosclerosis and increased bone mass, predominantly involving spine, pelvis, and skull. It is closely related to functional defect of osteoclasts caused by chloride voltage-gated channel 7 (CLCN7) gene mutations. In this study, we aimed to identify the pathogenic mutation in a Korean patient with ADO II using whole exome sequencing. METHODS: We evaluated the clinical, biochemical, and radiographic analysis of a 68-year-old woman with ADO II. We also performed whole exome sequencing to identify pathogenic mutation of a rare genetic disorder of the skeleton. Moreover, a polymorphism phenotyping program, Polymorphism Phenotyping v2 (PolyPhen-2), was used to assess the effect of the identified mutation on protein function. RESULTS: Whole exome sequencing using peripheral leukocytes revealed a heterozygous c.296A>G missense mutation in the CLCN7 gene. The mutation was also confirmed using Sanger sequencing. The mutation c.296A>G was regarded to have a pathogenic effect by PolyPhen-2 software. CONCLUSION: We detect a heterozygous mutation in CLCN7 gene of a patient with ADO II, which is the first report in Korea. Our present findings suggest that symptoms and signs of ADO II patient having a c.296A>G mutation in CLCN7 may appear at a very late age. The present study would also enrich the database of CLCN7 mutations and improve our understanding of ADO II.

Overcoming osteoporosis and beyond: Locomotive syndrome or dysmobility syndrome

No abstract available.

Oncogenes, mitochondrial metabolism, and quality control in differentiated thyroid cancer

Thyroid cancer is one of the most common malignancies of endocrine organs, and its incidence rate has increased steadily over the past several decades. Most differentiated thyroid tumors derived from thyroid epithelial cells exhibit slow-growing cancers, and patients with these tumors can achieve a good prognosis with surgical removal and radioiodine treatment. However, a small proportion of patients present with advanced thyroid cancer and are unusually resistant to current drug treatment modalities. Thyroid tumorigenesis is a complex process that is regulated by the activation of oncogenes, inactivation of tumor suppressors, and alterations in programmed cell death. Mitochondria play an essential role during tumor formation, progression, and metastasis of thyroid cancer. Recent studies have successfully observed the mitochondrial etiology of thyroid carcinogenesis. This review focuses on the recent progress in understanding the molecular mechanisms of thyroid cancer relating to altered mitochondrial metabolism.

Disease-Specific Mortality of Differentiated Thyroid Cancer Patients in Korea: A Multicenter Cohort Study

BACKGROUND: Little is known regarding disease-specific mortality of differentiated thyroid cancer (DTC) patients and its risk factors in Korea. METHODS: We retrospectively reviewed a large multi-center cohort of thyroid cancer from six Korean hospitals and included 8,058 DTC patients who underwent initial surgery between 1996 and 2005. RESULTS: Mean age of patients at diagnosis was 46.2±12.3 years; 87% were females. Most patients had papillary thyroid cancer (PTC; 97%) and underwent total thyroidectomy (85%). Mean size of the primary tumor was 1.6±1.0 cm. Approximately 40% of patients had cervical lymph node (LN) metastases and 1.3% had synchronous distant metastases. During 11.3 years of follow-up, 150 disease-specific mortalities (1.9%) occurred; the 10-year disease-specific survival (DSS) rate was 98%. According to the year of diagnosis, the number of disease-specific mortality was not different. However, the rate of disease-specific mortality decreased during the study period (from 7.7% to 0.7%). Older age (≥45 years) at diagnosis, male, follicular thyroid cancer (FTC) versus PTC, larger tumor size (>2 cm), presence of extrathyroidal extension (ETE), lateral cervical LN metastasis, distant metastasis and tumor node metastasis (TNM) stage were independent risk factors of disease-specific mortality of DTC patients. CONCLUSION: The rate of disease-specific mortality of Korean DTC patients was 1.9%; the 10-year DSS rate was 98% during 1996 to 2005. Older age at diagnosis, male, FTC, larger tumor size, presence of ETE, lateral cervical LN metastasis, distant metastasis, and TNM stages were significant risk factors of disease-specific mortality of Korean DTC patients.

The Eosinophil Count Tends to Be Negatively Associated with Levels of Serum Glucose in Patients with Adrenal Cushing Syndrome

BACKGROUND: Cushing syndrome is characterized by glucose intolerance, cardiovascular disease, and an enhanced systemic inflammatory response caused by chronic exposure to excess cortisol. Eosinopenia is frequently observed in patients with adrenal Cushing syndrome, but the relationship between the eosinophil count in peripheral blood and indicators of glucose level in patients with adrenal Cushing syndrome has not been determined. METHODS: A retrospective study was undertaken of the clinical and laboratory findings of 40 patients diagnosed with adrenal Cushing syndrome at Chungnam National University Hospital from January 2006 to December 2016. Clinical characteristics, complete blood cell counts with white blood cell differential, measures of their endocrine function, description of imaging studies, and pathologic findings were obtained from their medical records. RESULTS: Eosinophil composition and count were restored by surgical treatment of all of the patients with adrenal Cushing disease. The eosinophil count was inversely correlated with serum and urine cortisol, glycated hemoglobin, and inflammatory markers in the patients with adrenal Cushing syndrome. CONCLUSION: Smaller eosinophil populations in patients with adrenal Cushing syndrome tend to be correlated with higher levels of blood sugar and glycated hemoglobin. This study suggests that peripheral blood eosinophil composition or count may be associated with serum glucose levels in patients with adrenal Cushing syndrome.

Effect of Atorvastatin on Growth Differentiation Factor-15 in Patients with Type 2 Diabetes Mellitus and Dyslipidemia

BACKGROUND: Elevated serum levels of growth differentiation factor-15 (GDF-15) are associated with type 2 diabetes. Therefore, the effects of atorvastatin on metabolic parameters and GDF-15 levels in patients with type 2 diabetes and dyslipidemia were evaluated. METHODS: In this prospective randomized trial from February 2013 to March 2014, 50 consecutive type 2 diabetic patients with a low density lipoprotein cholesterol (LDL-C) levels > or =100 mg/dL were enrolled. The patients were divided into two groups based on the amount of atorvastatin prescribed, 10 mg/day (n=23) or 40 mg/day (n=27). The effect of atorvastatin on metabolic parameters, including lipid profiles and GDF-15 levels, at baseline and after 8 weeks of treatment were compared. RESULTS: The baseline metabolic parameters and GDF-15 levels were not significantly different between the two groups. After 8 weeks of treatment, the total cholesterol (TC) and LDL-C levels were significantly decreased in both groups. The mean changes in TC and LDL-C levels were more significant in the 40 mg atorvastatin group. The GDF-15 level was decreased in the 10 mg atorvastatin group, from 1,460.6+/-874.8 to 1,451.0+/-770.8 pg/mL, and was increased in the 40 mg atorvastatin group, from 1,271.6+/-801.0 to 1,341.4+/-855.2 pg/mL. However, the change in the GDF-15 level was not statistically significant in the 10 or 40 mg atorvastatin group (P=0.665 and P=0.745, respectively). CONCLUSION: The GDF-15 levels were not significantly changed after an 8-week treatment with atorvastatin in type 2 diabetic patients.

Multiple Fractures in Patient with Graves' Disease Accompanied by Isolated Hypogonadotropic Hypogonadism

Isolated hypogonadotropic hypogonadism (IHH) is known to decrease bone mineral density due to deficiency of sex steroid hormone. Graves' disease is also an important cause of secondary osteoporosis. However, IHH does not preclude the development of primary hyperthyroidism caused by Graves' disease, leading to more severe osteoporosis rapidly. Here, we describe the first case of 35-year-old Asian female patient with IHH accompanied by Graves' disease and osteoporosis-induced multiple fractures. Endocrine laboratory findings revealed preserved anterior pituitary functions except for secretion of gonadotropins and showed primary hyperthyroidism with positive autoantibodies. Sella magnetic resonance imaging showed slightly small sized pituitary gland without mass lesion. Dual energy X-ray absorptiometry revealed severe osteoporosis in lumbar spine and femur neck of the patient. Plain film radiography of the pelvis and shoulder revealed a displaced and nondisplaced fracture, respectively. After surgical fixation with screws for the femoral fracture, the patient was treated with antithyroid medication, calcium, and vitamin D until now and has been recovering fairly well. We report a patient of IHH with Graves' disease and multiple fractures that is a first case in Korea.

Letter: Insufficient Experience in Thyroid Fine-Needle Aspiration Leads to Misdiagnosis of Thyroid Cancer (Endocrinol Metab 2014;29:293-9, Jung Il Son et al.)

No abstract available.

Genetic and Clinical Characteristics of Korean Patients with Isolated Hypoparathyroidism: From the Korean Hypopara Registry Study

Isolated hypoparathyroidism (IH) shows heterogeneous phenotypes and can be caused by defects in a variety of genes. The goal of our study was to determine the clinical features and to analyze gene mutations in a large cohort of Korean patients with sporadic or familial IH. We recruited 23 patients. They showed a broad range of onset age and various values of biochemical data. Whole exome sequencing was performed on two affected cases and one unaffected individual in a family. All coding exons and exon-intron borders of GCMB, CASR, and prepro-PTH were sequenced using PCR-amplified DNA. In one family who underwent the whole exome sequencing analysis, approximately 300 single nucleotide changes emerged as candidates for genetic alteration. Among them, we identified a functional mutation in exon 2 of GCMB (C106R) in two affected cases. Besides, heterozygous gain-of-function mutations in the CASR gene were found in other subjects; D410E and P221L. We also found one single nucleotide polymorphism (SNP) in the prepro-PTH gene, five SNPs in the CASR gene, and four SNPs in the GCMB gene. The current study represents a variety of biochemical phenotypes in IH patients with the molecular genetic diagnosis of IH.

A Case of Primary Hyperparathyroidism Caused by Solitary Parathyroid Adenoma That was Not Detected by Both Ultrasonography and Sestamibi Scan

Thanks to advances in assay techniques and routine measurements in serum chemical analysis, primary hyperparathyroidism has become far more frequently detected, and the number of asymptomatic patients has substantially increased. In the majority of patients (85%), a solitary adenoma is the underlying cause of primary hyperparathyroidism. Surgical excision is the treatment of choice for most cases of primary hyperparathyroidism; this procedure has a relatively high success rate. In the past decade, improvements in preoperative imaging have played a major role in a targeted operative approach, which allows for minimally invasive surgery to be performed. The success of parathyroid surgery depends on the accurate preoperative localization of parathyroid adenoma. In this study, we report the case of a 54 year-old woman with primary hyperparathyroidism who presented with left buttock and leg pain. For localization of the parathyroid lesion, an ultrasonography and a 99mTc-sestamibi scan were initially performed, but these attempts failed to localize the lesion. We then carried out contrast-enhanced CT; thereafter, a single parathyroid adenoma was detected. Therefore, in patients with negative results on both ultrasonography and 99mTc-sestamibi scan, contrast-enhanced CT may prove helpful for preoperative parathyroid localization.