Analysis of Patients with NET G1/G2 Neuroendocrine Tumors of the Small Intestine in the Course of Carcinoid Heart Disease-A Retrospective Study.

Neuroendocrine neoplasms of the small intestine (SI-NENs) are one of the most commonly recognized gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs). Carcinoid heart disease (CHD) is the primary cause of death in patients with the carcinoid syndrome (CS). The aim of this retrospective study was to evaluate possible factors impacting upon overall survival (OS) in subjects with both neuroendocrine tumors (NETs) G1/G2 of the small intestine (SI-NET) and CHD. Enrolled in our study of 275 patients with confirmed G1/G2 SI-NET, were 28 (10%) individuals with CHD. Overall survival was assessed using the Kaplan-Meier method. The Cox-Mantel test was used to determine how OS varied between groups. A Cox proportional hazards model was used to conduct univariate analyses of predictive factors for OS and estimate hazard ratios (HRs). Of the 28 individuals with confirmed carcinoid heart disease, 12 (43%) were found to have NET G1 and 16 (57%) were found to have NET G2. Univariate analysis revealed that subjects with CHD and without resection of the primary tumor had a lower OS. Our retrospective study observed that patients who presented with CHD and without resection of primary tumor had worse prognosis of survival. These results suggest that primary tumors may need to be removed when feasible, but further research is needed. However, no solid recommendations can be issued on the basis of our single retrospective study.

What do we know about carcinoid heart disease in the present era?

Carcinoid heart disease (CHD) is a severe complication of carcinoid syndrome (CS) found primarily in patients with small intestine neuroendocrine neoplasms (SI-NENs). Patients who develop CHD have significantly worse morbidity and mortality outcomes, highlighting the importance of clinical practice recommendations for CHD screening, diagnosis, and treatment that are both consistent and practical. CHD is characterized by white plaque-like deposits on the endocardial surface of heart structures, generally affecting the right heart valves, causing tricuspid and pulmonary regurgitation and, less commonly, valve stenosis. Cardiac imaging is essential for both the diagnosis and management of CHD. Previously, imaging for CHD was mostly achieved by echocardiography, but more recently, imaging has become multimodal. N-terminal pro-B-type natriuretic peptide (NT-proBNP) and 5-hydroxyindoleacetic acid in the urine (u5-HIAA) are currently the most effective markers used in screening CS patients and evaluating CHD severity. Managing patients with CHD is challenging since both systemic malignant disease and cardiac involvement must be treated concurrently. Early diagnosis and surgical intervention when required are critical to patient prognosis, especially in those without primary tumor resection. Valve replacement surgery is the most effective treatment for patients with advanced carcinoid heart disease for alleviating cardiac symptoms and contributing to survival outcomes. To deliver effective patient treatment, multidisciplinary team collaboration is needed. This review summarizes current research findings on CHD pathogenesis, clinical and epidemiological features, useful biomarkers and imaging modalities, and treatment strategies.

Myocardial perfusion imaging using single-photon emission computed tomography with cadmium-zinc-telluride technology.

Myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT) is a well-established diagnostic approach for patients with suspected or confirmed coronary artery disease (CAD). In the present century, nuclear cardiology has benefited immensely from advances in imaging instrumentation and technology. Dedicated cardiac SPECT cameras incorporating novel, highly efficient cadmium-zinc-telluride (CZT) detectors, collimators, and system designs have evolved as a result of the expansion of nuclear cardiology. A vast amount of evidence is emerging, demonstrating the new technology's advantages over the traditional gamma cameras. Myocardial perfusion imaging (MPI) using gamma-cameras with CZT detectors may be performed with the limited injected activity of radiotracer and recorded times. The use of CZT's dynamic acquisition of myocardial perfusion imaging in clinical practice may help cardiologists in detecting hemodynamically significant CAD. In this article, we present the current state of knowledge on cardiac CZT-SPECT scanners, a summary of the literature published on validation studies, radiation dose reduction, and dynamic acquisition, as well as a comparison of conventional myocardial perfusion imaging with invasive coronary angiography.

Chromogranin A (CgA) as a biomarker in carcinoid heart disease and NETG1/G2 neuroendocrine neoplasms of the small intestine (SI-NENs) related carcinoid syndrome.

INTRODUCTION: Progression of carcinoid syndrome (CS) to carcinoid heart disease (CHD) is difficult to predict. This retrospective analysis evaluates the use of chromogranin A (CgA), a biomarker widely used in the diagnosis of neuroendocrine tumours (NET), in monitoring CS and disease progression. PATIENTS AND METHODS: 108 patients with confirmed CS, selected from a group of 351 patients with neuroendocrine neoplasms of the small intestine (SI-NENs), including NETG1 well 40% and NETG2 60% moderately differentiated NET. CgA concentration was measured during initial diagnosis and clinical follow up in 84 patients, 27 of them subsequently developed CHD. The patient's overall survival (OS) was evaluated using the Kaplan-Meier method. RESULTS: Patients with CHD, were found to have significantly shorter OS than patients with CS but without CHD (67.22 vs. 73.03 months). Univariate and multivariate analyses revealed that initial high concentration of CgA and/or increased concentration of CgA is significantly associated with decreased median OS in patients with CS (p<0.05). CONCLUSION: CgA has potential as a clinically useful biomarker in reporting disease status and predicting outcome in patients with CS and with CHD.

Intrarenal hemodynamics and kidney function in pheochromocytoma and paraganglioma before and after surgical treatment.

PURPOSE: Current evidence regarding renal involvement in pheochromocytoma and paraganglioma (PPGL) is scant. More accurate diagnostic methods, such as renal Doppler ultrasound for intrarenal hemodynamic studies, may provide more detailed information on renal function. It might be postulated that renal function in PPGL patients might be altered by high blood pressure and excess secretion of catecholamines. The aim of this prospective study was to assess intrarenal blood flow parameters in PPGL patients included in the prospective monoamine-producing tumour (PMT) study and to evaluate the effects of normalisation of catecholamine production after surgical treatment on long-term renal function. MATERIALS AND METHODS: Seventy consecutive patients (aged 46.5 ± 14.0 years) with PPGL were included. Forty-eight patients from the PMT study cohort, matched for age, gender, blood pressure level and presence of hypertension, served as a control group. Renal artery doppler ultrasound spectral analysis included mean resistance index (RRI) and pulsatility index (PI). Forty-seven patients completed 12 months follow-up. RESULTS: There were no differences in renal parameters such as RRI, PI and kidney function between PPGL and non-PPGL patients as assessed by renal ultrasound, serum creatinine, eGFR and albumin excretion rate. No correlations between kidney function parameters, intrarenal doppler flow parameters and plasma catecholamines were observed in PPGL patients. At 12 months after surgery, no differences in creatinine level, eGFR, albumin excretion rate, RI and PI were found as compared to baseline results. CONCLUSIONS: In contrast to patients with other forms of secondary hypertension, our study did not show differences in intrarenal blood flow parameters and renal function between PPGL and non-PPGL subjects. Intrarenal hemodynamics and renal function did not change after normalisation of catecholamine levels by surgical treatment.

Functional significance of germline EPAS1 variants.

Mosaic or somatic EPAS1 mutations are associated with a range of phenotypes including pheochromocytoma and/or paraganglioma (PPGL), polycythemia and somatostatinoma. The pathogenic potential of germline EPAS1 variants however is not well understood. We report a number of germline EPAS1 variants occurring in patients with PPGL, including a novel variant c.739C>A (p.Arg247Ser); a previously described variant c.1121T>A (p.Phe374Tyr); several rare variants, c.581A>G (p.His194Arg), c.2353C>A (p.Pro785Thr) and c.2365A>G (p.Ile789Val); a common variant c.2296A>C (p.Thr766Pro). We performed detailed functional studies to understand their pathogenic role in PPGL. In transient transfection studies, EPAS1/HIF-2α p.Arg247Ser, p.Phe374Tyr and p.Pro785Thr were all stable in normoxia. In co-immunoprecipitation assays, only the novel variant p.Arg247Ser showed diminished interaction with pVHL. A direct interaction between HIF-2α Arg247 and pVHL was confirmed in structural models. Transactivation was assessed by means of a HRE-containing reporter gene in transiently transfected cells, and significantly higher reporter activity was only observed with EPAS1/HIF-2α p.Phe374Tyr and p.Pro785Thr. In conclusion, three germline EPAS1 variants (c.739C>A (p.Arg247Ser), c.1121T>A (p.Phe374Tyr) and c.2353C>A (p.Pro785Thr)) all have some functional features in common with somatic activating mutations. Our findings suggest that these three germline variants are hypermorphic alleles that may act as modifiers to the expression of PPGLs.

Left Ventricular Structural and Functional Alterations in Patients With Pheochromocytoma/Paraganglioma Before and After Surgery.

OBJECTIVES: This study sought to evaluate left ventricular (LV) structure and function in pheochromocytoma and paraganglioma (PPGL) patients before and after curative surgery. BACKGROUND: Data on catecholamine-induced effects on LV structure and function in patients with PPGL are limited and conflicting. METHODS: The study evaluated 81 consecutive patients with a PPGL, among whom 66 were evaluated 12 months after tumor removal. Fifty patients matched for age, sex, hypertension presence, and blood pressure (BP) levels served as a control group (non-PPGL group). Echocardiography was employed to assess the LV mass index (LVMI), systolic function including speckle tracking echocardiography, and diastolic function. RESULTS: Patients with PPGL were characterized by higher LVMI (median 103 [interquartile range (IQR): 88 to 132] g/m2 vs. median 94 [IQR: 74 to 106] g/m2; p = 0.006) and frequency of LV hypertrophy (44.4% vs. 24.0%; p = 0.018) compared with the non-PPGL group. Patients with PPGLs were characterized by lower global longitudinal strain (GLS) and early diastolic mitral annular velocity compared with patients in the non-PPGL group (median -17.2% [IQR: 15.6% to 18.9%] vs. median -19.3% [IQR: 17.7% to 20.6%]; p < 0.001; and median 11.1 [IQR: 8.3 to 13.0] cm/s vs. median 12.3 [IQR: 10.6 to 14.6] cm/s; p = 0.018, respectively). Presence of LV hypertrophy and GLS were independently associated with plasma free metanephrine concentrations. In operated patients, there were lower frequencies of LV hypertrophy (39.4% vs. 22.7%; p = 0.003), LVMI (median 98 [IQR: 85 to 115] g/m2 vs. median 90 [IQR: 76 to 109] g/m2; p < 0.001), and the ratio of transmitral early diastolic velocity to early diastolic mitral annular velocity (median 6.8 [IQR: 5.5 to 8.6] vs. median 6.0 [IQR: 5.0 to 7.6]; p = 0.005) but higher values for GLS (median -17.4 [IQR: -15.8 to 19.1] vs. median -18.5 [IQR: -17.1 to 20.1] p < 0.001) after compared with before surgery. CONCLUSIONS: Catecholamine excess in patients with PPGLs can lead not only to LV hypertrophy, but also to impairment of systolic LV function and subclinical alterations of diastolic LV function, independently of BP levels. These structural and functional changes are reversible after surgical intervention.

Primary hyperparathyroidism as first manifestation in multiple endocrine neoplasia type 2A: an international multicenter study.

OBJECTIVE: Multiple endocrine neoplasia type 2A (MEN 2A) is a rare syndrome caused by RET germline mutations and has been associated with primary hyperparathyroidism (PHPT) in up to 30% of cases. Recommendations on RET screening in patients with apparently sporadic PHPT are unclear. We aimed to estimate the prevalence of cases presenting with PHPT as first manifestation among MEN 2A index cases and to characterize the former cases. DESIGN AND METHODS: An international retrospective multicenter study of 1085 MEN 2A index cases. Experts from MEN 2 centers all over the world were invited to participate. A total of 19 centers in 17 different countries provided registry data of index cases followed from 1974 to 2017. RESULTS: Ten cases presented with PHPT as their first manifestation of MEN 2A, yielding a prevalence of 0.9% (95% CI: 0.4-1.6). 9/10 cases were diagnosed with medullary thyroid carcinoma (MTC) in relation to parathyroid surgery and 1/10 was diagnosed 15 years after parathyroid surgery. 7/9 cases with full TNM data were node-positive at MTC diagnosis. CONCLUSIONS: Our data suggest that the prevalence of MEN 2A index cases that present with PHPT as their first manifestation is very low. The majority of index cases presenting with PHPT as first manifestation have synchronous MTC and are often node-positive. Thus, our observations suggest that not performing RET mutation analysis in patients with apparently sporadic PHPT would result in an extremely low false-negative rate, if no other MEN 2A component, specifically MTC, are found during work-up or resection of PHPT.

Retinal arterial remodeling in patients with pheochromocytoma or paraganglioma and its reversibility following surgical treatment.

OBJECTIVE: Structural abnormalities in resistance arteries are a hallmark of patients with hypertension. In hypertensive patients with pheochromocytoma or paraganglioma (PPGL), it is still a matter of debate whether structural vascular changes are because of elevated blood pressure (BP) or to toxic effects of elevated circulating catecholamines. Hence, the aim of our study was to assess whether catecholamine excess and/or elevated BP affect the structure of small retinal arteries in patients with catecholamine-producing tumors. METHODS: The study included 27 patients with PPGL and 27 hypertensive patients. All patients underwent biochemical tests for catecholamine excess, echocardiography and analyses of scanning-laser-Doppler-flowmetry (SLDF) both at baseline and 12 months following surgical resection of PPGL. RESULTS: Baseline retinal arterial diameter, arterial wall thickness and wall cross sectional area (WCSA) were higher in patients with PPGL as compared with subjects without PPGL (arterial diameter: 110 ±â€Š16.5 vs. 99.5 ±â€Š10.8 µm, wall thickness: 16.3 ±â€Š6.0 vs. 13.5 ±â€Š4.0 µm, WCSA: 4953.9 ±â€Š2472.8 vs. 3784.1 ±â€Š1446.3 µm, P < 0.05). Significant correlations were noted between wall thickness and WCSA and echocardiographic parameters assessing diastolic and systolic function of left ventricle. No correlations between retinal parameters, BP level and plasma concentrations of metanephrines were observed. In patients with PPGL, there were postoperative decreases in wall thickness (16.4 ±â€Š15.8 vs. 14.8 ±â€Š4.7 µm; P = 0.011) and WLR (0.42 ±â€Š0.13 vs. 0.37 ±â€Š0.10; P = 0.003) at 12 months after surgical removal of tumors. CONCLUSION: This is the first study to demonstrate that catecholamine excess is related to thickening of retinal arteries independent of BP and reversible after surgical cure. These data support a role of catecholamines in vascular remodeling in PPGL patients.

Systematic and Multidisciplinary Evaluation of Fibromuscular Dysplasia Patients Reveals High Prevalence of Previously Undetected Fibromuscular Dysplasia Lesions and Affects Clinical Decisions: The ARCADIA-POL Study.

Fibromuscular dysplasia (FMD), regarded as a generalized vascular disease, may affect all vascular beds and may result in arterial stenosis, occlusion, aneurysm, or dissection. It has been proposed to systematically evaluate all vascular beds in patients with FMD, regardless of initial FMD involvement. However, the impact of this approach on clinical decisions and on management is unknown. Within the prospective ARCADIA-POL study (Assessment of Renal and Cervical Artery Dysplasia-Poland), we evaluated 232 patients with FMD lesions confirmed in at least one vascular bed, out of 343 patients included in the registry. All patients underwent a detailed clinical evaluation including computed tomography angiography of intracranial and cervical arteries, as well as computed tomography angiography of the abdominal aorta, its branches, and upper and lower extremity arteries. In the study group, FMD lesions were most frequently found in renal arteries (87.5%). FMD was also found in cerebrovascular (24.6%), mesenteric (13.8%), and upper (3.0%) and lower extremity (9.9 %) arteries. Newly diagnosed FMD lesions were found in 34.1% of the patients, and previously undetected vascular complications were found in 25% of the patients. Among all FMD patients included in the study, one out of every 4 evaluated patients qualified for interventional treatment due to newly diagnosed FMD lesions or vascular complications. The ARCADIA-POL study shows for the first time that the systematic and multidisciplinary evaluation of patients with FMD based on a whole-body computed tomography angiography scan has an impact on their clinical management. This proved the necessity of the systematic evaluation of all vascular beds in patients with FMD, regardless of initial FMD involvement.

Comparison of Pheochromocytoma-Specific Morbidity and Mortality Among Adults With Bilateral Pheochromocytomas Undergoing Total Adrenalectomy vs Cortical-Sparing Adrenalectomy.

Importance: Large studies investigating long-term outcomes of patients with bilateral pheochromocytomas treated with either total or cortical-sparing adrenalectomies are needed to inform clinical management. Objective: To determine the association of total vs cortical-sparing adrenalectomy with pheochromocytoma-specific mortality, the burden of primary adrenal insufficiency after bilateral adrenalectomy, and the risk of pheochromocytoma recurrence. Design, Setting, and Participants: This cohort study used data from a multicenter consortium-based registry for 625 patients treated for bilateral pheochromocytomas between 1950 and 2018. Data were analyzed from September 1, 2018, to June 1, 2019. Exposures: Total or cortical-sparing adrenalectomy. Main Outcomes and Measures: Primary adrenal insufficiency, recurrent pheochromocytoma, and mortality. Results: Of 625 patients (300 [48%] female) with a median (interquartile range [IQR]) age of 30 (22-40) years at diagnosis, 401 (64%) were diagnosed with synchronous bilateral pheochromocytomas and 224 (36%) were diagnosed with metachronous pheochromocytomas (median [IQR] interval to second adrenalectomy, 6 [1-13] years). In 505 of 526 tested patients (96%), germline mutations were detected in the genes RET (282 patients [54%]), VHL (184 patients [35%]), and other genes (39 patients [7%]). Of 849 adrenalectomies performed in 625 patients, 324 (52%) were planned as cortical sparing and were successful in 248 of 324 patients (76.5%). Primary adrenal insufficiency occurred in all patients treated with total adrenalectomy but only in 23.5% of patients treated with attempted cortical-sparing adrenalectomy. A third of patients with adrenal insufficiency developed complications, such as adrenal crisis or iatrogenic Cushing syndrome. Of 377 patients who became steroid dependent, 67 (18%) developed at least 1 adrenal crisis and 50 (13%) developed iatrogenic Cushing syndrome during median (IQR) follow-up of 8 (3-25) years. Two patients developed recurrent pheochromocytoma in the adrenal bed despite total adrenalectomy. In contrast, 33 patients (13%) treated with successful cortical-sparing adrenalectomy developed another pheochromocytoma within the remnant adrenal after a median (IQR) of 8 (4-13) years, all of which were successfully treated with another surgery. Cortical-sparing surgery was not associated with survival. Overall survival was associated with comorbidities unrelated to pheochromocytoma: of 63 patients who died, only 3 (5%) died of metastatic pheochromocytoma. Conclusions and Relevance: Patients undergoing cortical-sparing adrenalectomy did not demonstrate decreased survival, despite development of recurrent pheochromocytoma in 13%. Cortical-sparing adrenalectomy should be considered in all patients with hereditary pheochromocytoma.

A Clinical Efficacy of PRRT in Patients with Advanced, Nonresectable, Paraganglioma-Pheochromocytoma, Related to SDHx Gene Mutation.

Paragangliomas and pheochromytomas (PPGLs) exhibit variable malignancy, advanced/hormonally active/progressive need therapy. PRRT (Peptide Receptor Radionuclide Therapy) could be an option for these patients. To evaluate the effectiveness of PRRT (90Y DOTATATE), based on overall survival (OS) and progression-free survival (PFS), in patients with PPGLs, related to SDHx gene mutation, we conducted a prospective open-label, single-center, phase II study. Thirteen patients were observed, eight PGL1 and five PGL4, all with advanced, non-resectable tumors, and eight had metastases. All were treated with 90Y DOTATATE. Efficacy was based on OS and PFS, and radiological response was based on RECIST. Hormonal activity was evaluated using serum-fractionated free catecholamines. Eight subjects had a clinical response, three were stable, and two exhibited disease progression. Among four patients with hormonally-active PPGLs, three showed a reduction and one showed normalization. OS for all was 68.0 months; PFS was 35.0 months. OS in PGL4 = 25.0 vs. N.R. (not reached) in PGL1. PFS in PGL4 = 12.0 vs. N.R. in PGL1. A difference was seen in the OS and PFS in patients who did not respond clinically, compared to those who did, OS = 22.0 vs. N.R. PFS = 7.0 vs. N.R. A difference in the OS and PFS was noted in patients with liver and bone involvement compared to those without. PRRT is an effective therapy in selected population of patients with SDHx, in those with locally-advanced, non-resectable tumors. Furthermore, it is effective regardless of the secretory status.

Natural history, treatment, and long-term follow up of patients with multiple endocrine neoplasia type 2B: an international, multicentre, retrospective study.

BACKGROUND: Multiple endocrine neoplasia type 2B is a rare syndrome caused mainly by Met918Thr germline RET mutation, and characterised by medullary thyroid carcinoma, phaeochromocytoma, and extra-endocrine features. Data are scarce on the natural history of multiple endocrine neoplasia type 2B. We aimed to advance understanding of the phenotype and natural history of multiple endocrine neoplasia type 2B, to increase awareness and improve detection. METHODS: This study was a retrospective, multicentre, international study in patients carrying the Met918Thr RET variant with no age restrictions. The study was done with registry data from 48 centres globally. Data from patients followed-up from 1970 to 2016 were retrieved from May 1, 2016, to May 31, 2018. Our primary objectives were to determine overall survival, and medullary thyroid carcinoma-specific survival based on whether the patient had undergone early thyroidectomy before the age of 1 year. We also assessed remission of medullary thyroid carcinoma, incidence and treatment of phaeochromocytoma, and the penetrance of extra-endocrine features. FINDINGS: 345 patients were included, of whom 338 (98%) had a thyroidectomy. 71 patients (21%) of the total cohort died at a median age of 25 years (range <1-59). Thyroidectomy was done before the age of 1 year in 20 patients, which led to long-term remission (ie, undetectable calcitonin level) in 15 (83%) of 18 individuals (2 patients died of causes unrelated to medullary thyroid carcinoma). Medullary thyroid carcinoma-specific survival curves did not show any significant difference between patients who had thyroidectomy before or after 1 year (comparison of survival curves by log-rank test: p=0·2; hazard ratio 0·35; 95% CI 0.07-1.74). However, there was a significant difference in remission status between patients who underwent thyroidectomy before and after the age of 1 year (p<0·0001). There was a significant difference in remission status between patients who underwent thyroidectomy before and after the age of 1 year (p<0·0001). In the other 318 patients who underwent thyroidectomy after 1 year of age, biochemical and structural remission was obtained in 47 (15%) of 318 individuals. Bilateral phaeochromocytoma was diagnosed in 156 (50%) of 313 patients by 28 years of age. Adrenal-sparing surgery was done in 31 patients: three (10%) of 31 patients had long-term recurrence, while normal adrenal function was obtained in 16 (62%) patients. All patients with available data (n=287) had at least one extra-endocrine feature, including 106 (56%) of 190 patients showing marfanoid body habitus, mucosal neuromas, and gastrointestinal signs. INTERPRETATION: Thyroidectomy done at no later than 1 year of age is associated with a high probability of cure. The reality is that the majority of children with the syndrome will be diagnosed after this recommended age. Adrenal-sparing surgery is feasible in multiple endocrine neoplasia type 2B and affords a good chance for normal adrenal function. To improve the prognosis of such patients, it is imperative that every health-care provider be aware of the extra-endocrine signs and the natural history of this rare syndrome. The implications of this research include increasing awareness of the extra-endocrine symptoms and also recommendations for thyroidectomy before the age of 1 year. FUNDING: None.

Biochemical Diagnosis of Chromaffin Cell Tumors in Patients at High and Low Risk of Disease: Plasma versus Urinary Free or Deconjugated O-Methylated Catecholamine Metabolites.

BACKGROUND: Measurements of plasma or urinary metanephrines are recommended for diagnosis of pheochromocytoma and paraganglioma (PPGL). What test offers optimal diagnostic accuracy for patients at high and low risk of disease, whether urinary free metanephrines offer advantages over deconjugated metanephrines, and what advantages are offered by including methoxytyramine in panels all remain unclear. METHODS: A population of 2056 patients with suspected PPGLs underwent prospective screening for disease using mass spectrometric-based measurements of plasma free, urinary deconjugated, and urinary free metanephrines and methoxytyramine. PPGLs were confirmed in 236 patients and were excluded in others on follow-up evaluation. RESULTS: Measurements of plasma free metabolites offered higher (P < 0.01) diagnostic sensitivity (97.9%) than urinary free (93.4%) and deconjugated (92.9%) metabolites at identical specificities for plasma and urinary free metabolites (94.2%) but at a lower (P < 0.005) specificity for deconjugated metabolites (92.1%). The addition of methoxytyramine offered little value for urinary panels but provided higher (P < 0.005) diagnostic performance for plasma measurements than either urinary panel according to areas under ROC curves (0.991 vs 0.972 and 0.964). Diagnostic performance of urinary and plasma tests was similar for patients at low risk of disease, whereas plasma measurements were superior to both urinary panels for high-risk patients. CONCLUSIONS: Diagnosis of PPGLs using plasma or urinary free metabolites provides advantages of fewer false-positive results compared with commonly measured deconjugated metabolites. The plasma panel offers better diagnostic performance than either urinary panel for patients at high risk of disease and, with appropriate preanalytics, provides the test of choice. Measurements of methoxytyramine in urine show limited diagnostic utility compared with plasma.