Plasma Normetanephrine Research Articles

Clinical utility of chromogranin A for the surveillance of succinate dehydrogenase B- and succinate dehydrogenase D-related paraganglioma.

Patients with mutations of succinate dehydrogenase B (SDHB) and succinate dehydrogenase D (SDHD) are at high risk of paraganglioma necessitating surveillance. Chromogranin A has been proposed as a biochemical marker of paraganglioma. We sought to determine the diagnostic utility of chromogranin A in a population-based SDHx sample. Tasmania is an island state with one tertiary referral centre for endocrine neoplasia. We performed a cross-sectional analysis of all adult SDHB ( n = 52) and SDHD ( n = 10) patients undergoing paraganglioma surveillance between 2011 and 2017. Chromogranin A was referenced against the outcome of paraganglioma surveillance with a minimum of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) and plasma metanephrines (metanephrine and normetanephrine). Chromogranin A correctly predicted the result of paraganglioma surveillance more often in patients with SDHB compared with those with SDHD (77% vs. 22%, P = 0.003). In the SDHB group, chromogranin A demonstrated a sensitivity of 67% and specificity of 79% compared with 22% and 0% in the SDHD group. Chromogranin A identified one of three PET/CT-visualized SDHB-related paragangliomas with normal plasma metanephrines at the expense of nine false-positive results. A normal chromogranin A demonstrated a negative predictive value of 92% for SDHB-related paraganglioma. In patients with SDHB, plasma normetanephrine and metanephrine offered superior specificity (100%, P = 0.01 and 100%, P < 0.01, respectively) with comparable sensitivity (67%, P = 1.0 and 11%, P = 0.06, respectively) to chromogranin A. Chromogranin A does not provide additive benefit to standard surveillance for predicting the presence of SDHB- or SDHD-related paraganglioma, but has a useful negative predictive value when normal in patients with SDHB mutation.

Rendimiento de las metanefrinas libres plasmáticas en el diagnóstico de los feocromocitomas y paragangliomas en la población asturiana

IntroductionPheochromocytoma and paraganglioma are uncommon tumors whose best known symptoms include high blood pressure, palpitations, headache, and sweating. Clinical identification is not easy, however, and requires biochemical tests that allow for early diagnosis, including measurement of metanephrines levels. The aim of this study was to assess the diagnostic performance of plasma free metanephrines (PMETs) and to verify the transferability of the reference values used. MethodsPMETs levels were measured by liquid chromatography coupled to tandem mass spectrometry. Other biochemical tests evaluated (plasma catecholamine, urine metanephrine, catecholamine and vanilmandelic acid levels) were performed by liquid chromatography with electrochemical detection. Requests of these tests from 01/09/2015 to 31/10/2017 were reviewed, and both the reference values (document EP28-A3c) and the parameters of biological variation (Fraser method) for PMETs were estimated. ResultsThe study sample consisted of 1,279 patients (61.3% females) aged 0-90 years, including 19 with pheochromocytoma/paraganglioma. Tests requested included: PMETs (n=662), catecholamines (n=589), metanephrines (n=586), and vanilmandelic acid (n=513) in urine, and plasma catecholamines (n=228). Tests with higher sensitivity were urinary fractionated metanephrines (91.7%) and PMETs (82.4%). When performance was compared in patients with both tests (n=243), they detected the same number of tumors (90.9%), but PMETs showed greater specificity (93.5% vs 88.8%). Plasma normetanephrine levels showed a significant association with age (rho=0.19, P<.0001). ConclusionPMETs and urinary fractionated metanephrines are the biochemical tests with better performance in diagnosis of pheochromocytomas/paragangliomas.

Multifocal pheochromocytoma-paraganglioma in a 29-year-old woman with cyanotic congenital heart disease

BackgroundMultifocal pheochromocytoma/paraganglioma presenting at an early age is commonly associated with a hereditary syndrome. Case ReportA 29-year-old woman was referred for evaluation of multifocal pheochromocytoma/paraganglioma. Interestingly, her family history did not include pheochromocytoma/paraganglioma, and comprehensive genetic testing for the well-documented pheochromocytoma/paraganglioma susceptibility genes was negative. Of note, this patient had a history of a complex cardiac defect resulting in cyanotic congenital heart disease and had never undergone operative repair. Thus she lived in a chronic hypoxic state with a baseline oxygen saturation of about 80%. Laboratory evaluation found marked increases in plasma norepinephrine and normetanephrines with normal epinephrine and metanephrines. Imaging revealed 4 aortocaval masses and a right adrenal mass. After appropriate preoperative preparation she underwent successful resection of each of the neoplasms, with pathologic testing revealing multifocal pheochromocytoma/paraganglioma. DiscussionThis case highlights a growing recognition of the potential development of pheochromocytoma/paraganglioma in patients with cyanotic congenital heart disease. The underlying pathophysiology and phenotypic similarities between pheochromocytoma/paraganglioma in patients with cyanotic congenital heart disease and those with mutations that lead to cellular pseudohypoxia are reviewed.

Establishment a diagnostic strategy of pheochromocytoma by plasma free metanephrines determined by liquid chromatography-tandem mass spectrometry

Objective To set up reference intervals of plasma free metanephrine (MN) and normetanephrine (NMN) by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and diagnostic strategies of pheochromocytoma. Methods 255 healthy people were recruited to set up reference intervals.110 patients with pheochromocytoma were also enrolled, in addition to 1 262 subjects taken as disease control group and 500 subjects taken as health control group. Positive rates of plasma free MN and NMN were compared among different groups. Diagnostic strategies were designed according to reference intervals and cut-off value with optimal specificity determined by receiver operating characteristic (ROC) curve. Results The reference intervals of MN and NMN are <64.97 pg/ml and <185.83 pg/ml, respectively. Significant differences in the level of MN and NMN were found between not only pheochromocytoma group and disease control group (Z=-17.410, P=0.000; Z=-17.278, P=0.000), but also pheochromocytoma group and health control group (Z=-16.434, P=0.000; Z=-16.439, P=0.000). We establish diagnostic strategy A for either of MN and NMN above the upper limit of the reference range and B for either of MN and NMN above specific diagnostic cutoff value to rule in or rule out the diagnosis of pheochromocytoma. Conclusion The reference intervals of plasma free MN and NMN by LC-MS/MS and diagnostic strategies of pheochromocytoma. Key words: Liquid chromatography-tandem mass spectrometry; Metanephrine; Normetanephrine; Pheochromocytoma

Radioimmunoassay of chromogranin A and free metanephrines in diagnosis of pheochromocytoma.

This work discusses the clinical performance of chromogranin A, free metanephrine and normetanephrine determination in plasma using a radioimmunoanalytical methods for the diagnosis of pheochromocytoma and paraganglioma. Blood samples were collected from 55 patients (46 pheochromocytomas, 9 paragangliomas). A sampling of biological materials was performed preoperatively and about one week, six months and one year after adrenal gland surgery. The comparative group without a diagnosis of pheochromocytoma/paraganglioma consisted of 36 pheochromocytoma/paraganglioma patients more than 4 months after adrenal gland surgery, and of 87 patients, 16 of them with multiple endocrine neoplasia, 9 with medullary and 5 with parafolicullar carcinoma of the thyroid gland. The rest were patients with various adrenal gland disorders. Chromogranin A, metanephrine and normetanephrine were determined in the EDTA-plasma using a radioimmunoassay kits Cisbio Bioassays, France and IBL International GmbH, Germany. Clinical sensitivity was 96 % for the combination of metanephrine and normetanephrine, and 93 % for chromogranin A. Clinical specificity was 100 % for the combination metanephrine and normetanephrine, and 96 % for chromogranin A. Falsely elevated levels of chromogranin A were observed in 1 patient with chronic renal insufficiency and 9 analyses were influenced by the administration of proton pump inhibitors. These results were excluded of CGA specificity. Both the combination of plasma free metanephrine, normetanephrine and chromogranin A as determined by radioimmunoassays, which are simple without the necessity of special laboratory material, are effective markers of pheochromocytoma or paraganglioma. Chromogranin A exerts association to malignity and all markers are associated with tumor mass.

Excessive Catecholamine Secretion and the Activation of the Renin-Angiotensin-Aldosterone-System in Patients with Pheochromocytoma: A Single Center Experience and Overview of the Literature.

Catecholamines stimulate renin-secretion in the juxtaglomerular cells of the kidney and a number of case reports suggest an association between pheochromocytoma and activation of the RAAS. Therefore, it could be asked whether patients suffering from pheochromocytoma with high concentrations of circulating catecholamines present with oversecretion of renin and aldosterone. We identified twelve patients with excessive catecholamine secretion due to pheochromocytoma and compared them to a group of twelve patients with essential hypertension (EH) with regard to the activation of the renin-angiotensin-aldosterone-system (RAAS). The PubMed database was screened for studies that investigate the association between pheochromocytoma and activation of the RAAS. The plasma concentrations of metanephrines (19.9-fold) and normetanephrines (29.5-fold) were significantly higher in the pheochromocytoma group than in the EH group. Renin and aldosterone levels were 1.3-fold and 1.6-fold higher, respectively, as compared to the EH group, whereas the differences were not statistically significant. There was no significant correlation between plasma metanephrine or normetanephrine levels and the plasma renin concentration (rs=0.077, rs=0.049, respectively) in our patients. The data from our institution and from review of literature suggest that an association between pheochromocytoma in the context of high plasma catecholamine levels and activation of the RAAS is present. However, results have not been consistent. Thus, other causes of RAAS-activation should be considered also in the presence of pheochromocytoma or reinvestigation for aldosteronism should be offered to such patients after removal of the catecholamine-producing tumour.

Postexercise cold water immersion modulates skeletal muscle PGC-1α mRNA expression in immersed and nonimmersed limbs: evidence of systemic regulation.

Mechanisms mediating postexercise cold-induced increases in PGC-1α gene expression in human skeletal muscle are yet to be fully elucidated but may involve local cooling effects on AMPK and p38 MAPK-related signaling and/or increased systemic β-adrenergic stimulation. Therefore, we aimed to examine whether postexercise cold water immersion enhancement of PGC-1α mRNA is mediated through local or systemic mechanisms. Ten subjects completed acute cycling (8 × 5 min at ~80% peak power output) followed by seated-rest (CON) or single-leg cold water immersion (CWI; 10 min, 8°C). Muscle biopsies were obtained preexercise, postexercise, and 3 h postexercise from a single limb in the CON condition but from both limbs in CWI [thereby providing tissue from a CWI and nonimmersed limb (NOT)]. Muscle temperature decreased up to 2 h postexercise following CWI (-5°C) in the immersed limb, with lesser changes observed in CON and NOT (-3°C, P < 0.05). No differences between limbs were observed in p38 MAPK phosphorylation at any time point (P < 0.05), whereas a significant interaction effect was present for AMPK phosphorylation (P = 0.031). Exercise (CON) increased gene expression of PGC-1α 3 h postexercise (~5-fold, P < 0.001). CWI augmented PGC-1α expression above CON in both the immersed (CWI; ~9-fold, P = 0.003) and NOT limbs (~12-fold, P = 0.001). Plasma normetanephrine concentration was higher in CWI vs. CON immediately postimmersion (860 vs. 665 pmol/l, P = 0.034). We report for the first time that local cooling of the immersed limb evokes transcriptional control of PGC-1α in the nonimmersed limb, suggesting increased systemic β-adrenergic activation of AMPK may mediate, in part, postexercise cold induction of PGC-1α mRNA.NEW & NOTEWORTHY We report for the first time that postexercise cold water immersion of one limb also enhances PGC-1α expression in a contralateral, nonimmersed limb. We suggest that increased systemic β-adrenergic stimulation, and not localized cooling per se, exerts regulatory effects on local signaling cascades, thereby modulating PGC-1α expression. Therefore, these data have important implications for research designs that adopt contralateral, nonimmersed limbs as a control condition while also increasing our understanding of the potential mechanisms underpinning cold-mediated PGC-1α responses.

Plasma methoxytyramine: clinical utility with metanephrines for diagnosis of pheochromocytoma and paraganglioma.

ContextMeasurements of plasma methoxytyramine, the O-methylated dopamine metabolite, are useful for detecting rare dopamine-producing pheochromocytomas and paragangliomas (PPGLs) and head and neck paragangliomas (HNPGLs), but utility for screening beyond that achieved using standard measurements of normetanephrine and metanephrine is unclear.ObjectiveEvaluation of the additional utility of methoxytyramine compared to plasma normetanephrine and metanephrine for diagnosis of PPGLs and HNPGLs.DesignComparative prospective study.MethodsComparison of mass spectrometric-based measurements of plasma methoxytyramine, normetanephrine and metanephrine in 1963 patients tested for PPGLs at six tertiary medical centers according to reference intervals verified in 423 normotensive and hypertensive volunteers.ResultsOf the screened patients, 213 had PPGLs and 38 HNPGLs. Using an upper cut-off of 0.10 nmol/L for methoxytyramine, 0.45 nmol/L for metanephrine and age-specific upper cut-offs for normetanephrine, diagnostic sensitivity with the addition of methoxytyramine increased from 97.2% to 98.6% for patients with PPGLs and from 22.1% to 50.0% for patients with HNPGLs, with a small decrease in specificity from 95.9% to 95.1%. Addition of methoxytyramine did not significantly alter areas under receiver operating characteristic curves for patients with PPGLs (0.984 vs 0.991), but did increase (P < 0.05) areas for patients with HNPGLs (0.627 vs 0.801). Addition of methoxytyramine also increased the proportion of patients with PPGLs who showed highly positive predictive elevations of multiple metabolites (70.9% vs 49.3%).ConclusionsWhile the benefit of additional measurements of plasma methoxytyramine for the detection of PPGLs is modest, the measurements do assist with positive confirmation of disease and are useful for the detection of HNPGLs.

Markers of physiological stress during exercise under conditions of normoxia, normobaric hypoxia, hypobaric hypoxia, and genuine high altitude

PurposeTo investigate whether there is a differential response at rest and following exercise to conditions of genuine high altitude (GHA), normobaric hypoxia (NH), hypobaric hypoxia (HH), and normobaric normoxia (NN).MethodMarkers of sympathoadrenal and adrenocortical function [plasma normetanephrine (PNORMET), metanephrine (PMET), cortisol], myocardial injury [highly sensitive cardiac troponin T (hscTnT)], and function [N-terminal brain natriuretic peptide (NT-proBNP)] were evaluated at rest and with exercise under NN, at 3375 m in the Alps (GHA) and at equivalent simulated altitude under NH and HH. Participants cycled for 2 h [15-min warm-up, 105 min at 55% Wmax (maximal workload)] with venous blood samples taken prior (T0), immediately following (T120) and 2-h post-exercise (T240).ResultsExercise in the three hypoxic environments produced a similar pattern of response with the only difference between environments being in relation to PNORMET. Exercise in NN only induced a rise in PNORMET and PMET.ConclusionBiochemical markers that reflect sympathoadrenal, adrenocortical, and myocardial responses to physiological stress demonstrate significant differences in the response to exercise under conditions of normoxia versus hypoxia, while NH and HH appear to induce broadly similar responses to GHA and may, therefore, be reasonable surrogates.

Changes in cardiovascular function based on adrenalin and norepinephrine metabolism in ovariectomized rats

Menopause is a cardiovascular risk factor in women, and cardiovascular changes during perimenopause can increase the risk. We observed the influence of plasma adrenalin and norepinephrine and their metabolites on the cardiovascular system and the rectification effect of estrogen in ovariectomized rats. Fifty-four adult female Sprague-Dawley rats were randomly divided into sham (Sham), ovariectomized (OVX), or ovariectomized+estrogen treatment groups (OVX+E), with 18 rats in each. The Sham and OVX groups were given normal saline and the OVX+E group was given estradiol valerate beginning 2weeks after ovariectomy and continuing for 4weeks. Radioimmunoassay, high-performance liquid chromatography, high-performance liquid chromatography-tandem mass spectrometry, and chromatography-spectrophotometry were used to detect estradiol, adrenalin, norepinephrine, metanephrine, and normetanephrine in plasma and vanillylmandelic acid in urine. Echocardiography, Doppler blood flow detection technologyand hamnatodynamometer were applied to assess cardiovascular function. After ovariectomy, levels of estrogen reduced, adrenalin and metanephrine increased, and norepinephrine and normetanephrine in the plasma and vanillylmandelic acid in urine decreased. Symptoms indicative of cardiac diastolic dysfunction, including decreased diastolic left ventricular cavity capacity, increased wall thickness and decreased cardiac rate were observed. Different degrees of vasomotor dysfunction appeared in different peripheral positions, and the tail vessels were in relatively systolic conditions. However, the claw pad vessels were diastolic. Besides, blood pressure also increased. After ovariectomy, estrogen levels reduced and the metabolic processes of adrenalin and norepinephrine changed, which impacted cardiovascular functions. Changes of adrenalin and norepinephrine and its metabolites were correlated with the cardiovascular function. Cardiovascular disease occurred during the perimenopausal period. Estrogen replacement therapy can mitigate, rectify, and improve menopause-related conditions such as hot flash.

Paraganglioma of the organ of Zuckerkandl associated with a somatic HIF2α mutation: A case report.

Paragangliomas of the organ of Zuckerkandl (OZ-PGL) are rare tumors that, in >70% of cases, occur in association with succinate dehydrogenase complex iron sulfur subunit B (SDHB) or SDHD gene mutations. The aim of the current study was to determine whether a somatic genetic defect in the hypoxia-inducible factor 2α (HIF2α) gene was present in a case of sporadic OZ-PGL. A 32-year-old African female presented with uncontrolled hypertension during the first trimester of pregnancy. A diagnostic hysteroscopy was performed 3 months after delivery, precipitating a hypertensive crisis. Thereafter, the patient was diagnosed with noradrenaline-secreting OZ-PGL. A complete blood count identified mild normocytic anemia of an inflammatory origin. Surgical removal of the tumor resulted in normalization of plasma and urinary normetanephrine levels. Genetic testing for germline mutations (including large deletions) in the von Hippel-Lindau tumor suppressor, SDHB, SDHC and SDHD genes was normal. However, a heterozygous missense mutation (c.1589Cys>Tyr) was detected in exon 12 of HIF2α, which results in a substitution of alanine 530 with valine (Ala530Val) in the HIF2α protein. A germline mutation was excluded based on the negative results of blood DNA testing. A three-dimensional homology model of Ala530Val was constructed, which showed impaired HIF2α/VHL interaction and decreased HIF2α ubiquitination. 1H-high-resolution magic-angle-spinning nuclear magnetic resonance spectroscopy detected low succinate levels and high α and β glucose levels. To the best of our knowledge, the present case represents the first of its kind to associate a somatic HIF2α gain-of-function mutation with OZ-PGL. It is therefore recommended that patients without germline SDHx mutations should be tested for HIF2α mutations.

Screening for phaeochromocytoma and paraganglioma: impact of using supine reference intervals for plasma metanephrines with samples collected from fasted/seated patients.

Background The Endocrine Society Clinical Practice Guideline on Phaeochomocytoma and Paraganglioma recommends phlebotomy for plasma-free metanephrines with patients fasted and supine using appropriately defined reference intervals. Studies have shown higher diagnostic sensitivities using these criteria. Further, with seated-sampling protocols, for result interpretation, reference intervals that do not compromise diagnostic sensitivity should be employed. Objective To determine the impact on diagnostic performance and financial cost of using supine reference intervals for result interpretation with our current plasma-free metanephrines fasted/seated-sampling protocol. Methods We conducted a retrospective cohort study of patients who underwent screening for PPGL using plasma-free metanephrines from 2009 to 2014 at Galway University Hospitals. Plasma-free metanephrines were measured using liquid chromatography-tandem mass spectrometry. Supine thresholds for plasma normetanephrine and metanephrine set at 610 pmol/L and 310 pmol/L, respectively, were used. Results A total of 183 patients were evaluated. Mean age of participants was 53.4 (±16.3) years. Five of 183 (2.7%) patients had histologically confirmed PPGL (males, n=4). Using seated reference intervals for plasma-free metanephrines, diagnostic sensitivity and specificity were 100% and 98.9%, respectively, with two false-positive cases. Application of reference intervals established in subjects supine and fasted to this cohort gave diagnostic sensitivity of 100% with specificity of 74.7%. Financial analysis of each pretesting strategy demonstrated cost-equivalence (€147.27/patient). Conclusion Our cost analysis, together with the evidence that fasted/supine-sampling for plasma-free metanephrines, offers more reliable exclusion of PPGL mandates changing our current practice. This study highlights the important advantages of standardized diagnostic protocols for plasma-free metanephrines to ensure the highest diagnostic accuracy for investigation of PPGL.

Comparison of the effects of nicotinic acid and nicotinamide degradation on plasma betaine and choline levels

The present study was to compare the effects of nicotinic acid and nicotinamide on the plasma methyl donors, choline and betaine. Thirty adult subjects were randomly divided into three groups of equal size, and orally received purified water (C group), nicotinic acid (300mg, NA group) or nicotinamide (300mg, NM group). Plasma nicotinamide, N1-methylnicotinamide, homocysteine, betaine and choline levels before and 1.5-h and 3-h post-dosing, plasma normetanephrine and metanephrine concentrations at 3-h post-dosing, and the urinary excretion of N1-methyl-2-pyridone-5-carboxamide during the test period were examined. The level of 3-h plasma nicotinamide, N1-methylnicotinamide, homocysteine, the urinary excretion of N1-methyl-2-pyridone-5-carboxamide and pulse pressure (PP) in the NM group was 221%, 3972%, 61%, 1728% and 21.2% higher than that of the control group (P<0.01, except homocysteine and PP P<0.05), while the 3-h plasma betaine, normetanephrine and metanephrine level in the NM group was 24.4%, 9.4% and 11.7% lower (P<0.05, except betaine P<0.01), without significant difference in choline levels. Similar but less pronounced changes were observed in the NA group, with a lower level of 3-h plasma N1-methylnicotinamide (1.90±0.20μmol/l vs. 3.62±0.27μmol/l, P<0.01) and homocysteine (12.85±1.39μmol/l vs. 18.08±1.02μmol/l, P<0.05) but a higher level of betaine (27.44±0.71μmol/l vs. 23.52±0.61μmol/l, P<0.05) than that of the NM group. The degradation of nicotinamide consumes more betaine than that of nicotinic acid at identical doses. This difference should be taken into consideration in niacin fortification.

Effects of Hydrocortisone on the Regulation of Blood Pressure: Results From a Randomized Controlled Trial.

Cardiovascular risk is increased in patients with secondary adrenal insufficiency, which may be ascribed to an unfavorable metabolic profile consequent to a relatively high hydrocortisone replacement dose. We determined the effects of a higher versus a lower glucocorticoid replacement dose on blood pressure (BP), the renin-angiotensin-aldosterone system, 11β-hydroxysteroid dehydrogenase enzyme activity and circulating (nor)metanephrines. Forty-seven patients with secondary adrenal insufficiency from the University Medical Center Groningen participated in this randomized double-blind crossover study. Patients randomly received 0.2-0.3 mg hydrocortisone/kg body weight followed by 0.4-0.6 mg hydrocortisone/kg body weight, or vice versa, each during 10 weeks. BP and regulating hormones were measured. The higher hydrocortisone dose resulted in an increase in systolic BP of 5 (12) mm Hg (P = .011), diastolic BP of 2 (9) mm Hg (P = .050), and a median [interquartile range] drop in plasma potassium of -0.1 [-0.3; 0.1] nmol/liter (P = .048). The higher hydrocortisone dose led to decreases in serum aldosterone of -28 [-101; 9] pmol/liter (P = .020) and plasma renin of -1.3 [-4.5; 1.2 ] pg/mL (P = .051), and increased the ratio of plasma and urinary cortisol to cortisone (including their metabolites) (P < .001 for all). Furthermore, on the higher dose, plasma and urinary normetanephrine decreased by -0.101 [-0.242; 0.029] nmol/liter (P < .001) and -1.48 [-4.06; 0.29] μmol/mol creatinine (P < .001) respectively. A higher dose of hydrocortisone increased systolic and diastolic BP and was accompanied by changes in the renin-angiotensin-aldosterone system, 11β-hydroxysteroid dehydrogenase enzyme activity, and circulating normetanephrine. This demonstrates that hydrocortisone dose even within the physiological range affects several pathways involved in BP regulation.

No influence of antihypertensive agents on plasma free metanephrines

BackgroundHypertension can be the predominant sign of pheochromocytoma (PCC) and sympathetic paraganglioma (sPGL) and screening for PCC/sPGL is often performed in patients who are already being treated with antihypertensive agents. There is very little information about the influence of antihypertensive drugs on plasma free metanephrines. The aim of this study was to determine whether commonly prescribed antihypertensive drugs can falsely elevate plasma free metanephrines concentrations measured by LC-MS/MS analysis. MethodsIn a prospective study we included patients with newly diagnosed hypertension, who started monotherapy with an antihypertensive agent (i.e. β-blocker, thiazide diuretic or angiotensin-converting enzyme (ACE) inhibitor). Plasma free metanephrine (MN) and normetanephrine (NMN) levels were measured before and one month after the start of the medication quantified by LC-MS/MS. ResultsBetween 2009 and 2014, 39 patients were included (β-blocker n=13, thiazide diuretic n=14 and ACE inhibitor n=12). In the whole group, the median plasma free MN and NMN concentrations at baseline were 0.19 [0.17–0.26] nmol/L and 0.56 [0.38–0.95] nmol/L. One month after the start of antihypertensive treatment, the median plasma free MN and NMN concentrations were comparable; 0.20 [0–16–0.24] nmol/L and 0.63 [0.39–0.75] nmol/L, respectively (P=0.43 and P=0.39). Separate analysis for each of the three antihypertensive agents examined did not reveal any significant changes in the median plasma free MN and NMN concentrations. ConclusionsThe measurement of plasma free MN and NMN with LC-MS/MS is not affected by use of β-blockers, diuretics and ACE inhibitors. Withdrawal of these drugs prior to the quantification of plasma metanephrines is therefore not necessary.

176-01: Radiofrequency cardiac denervation: scintigraphic evaluation of the effectiveness

Purpose: The aim of the study was to evaluate the role of radionuclide imaging with 123I-metaiodbenzilguanidine (123I-MIBG) in assessing of the cardiac radiofrequency denervation effectiveness. Methods and Materials: In this study were enrolled 32 patients with mitral valve (MV) disease: 21 patients with long-standing persistent atrial fibrillation, who was undergone MV surgery and the «Maze» procedure (Maze+ group) and 11 patients with sinus rhythm and with MV surgery without the «Maze» procedure (Maze- group). All patients underwent cardiac 123I-MIBG imaging prior and 10 days after surgery. The early and delayed heart-to-mediastinum ratio (HMR) and the washout rate (WR) were performed. Local denervation was evaluated on polar map images using the 17-segment model of left ventricle (LV). In addition, we determined the levels of norepinephrine, metanephrine, normetanephrine in plasma, obtained intraoperatively from the coronary sinus (CS) and the ascending aorta (Ao) before and after the main stage of the surgery. All patients were intraoperatively intake of histological material (left atrial appendage) to determine the distribution density of nerve endings in the myocardium. Results: In patients with AF the early HMR and delayed HMR prior surgery were significantly lower compared to patients with SR (p < 0.01). The washout rate of 123I-MIBG prior surgery in patients with AF was greater compared to patients with SR (p < 0.01). The HMR after surgery was significantly lower vs baseline in both groups (early HMR: 1,78 ± 0,17 vs 1,56 ± 0,19; p < 0,01 and 2,12 ± 0,25 vs 1,79 ± 0,18; p < 0,01; delayed HMR: 1,69 ± 0,21 vs 1,47 ± 0,19; p < 0,01 and 2,0 ± 0,22 vs 1,74 ± 0,19; p < 0,01). The WR after surgery was significantly increased vs baseline in both groups (27,3% ± 14,03% vs 35,0% ± 14,18%; p < 0,01 and 17,1% ± 13,7% vs 31% ± 16,15%; p < 0,01). After surgery sympathetic activity defect was increased only in the Maze+ group (12,7% ± 7,3% and 25,4% ± 8,5%; p < 0,01). The correlations between the cardiac 123I-MIBG parameters and the levels of norepinephrine, metanephrine, normetanephrine in plasma were examined. Cardiac 123I-MIBG parameters had significant correlations with transcardiac gradients (CS-Ao) of the norepinephrine and normetanephrine. Cardiac 123I-MIBG parameters had significant correlations with the distribution density of nerve endings in the myocardium. Conclusion: Results of this study indicated that the more sympathetic innervation abnormality prior surgery was observed in patients with AF. In patients who had undergone MV surgery without the «Maze» procedure, there were no significant changes in sympathetic activity defect in the early stage. The MV surgery itself doesn't influence the regional cardiac sympathetic activity. The evaluation of the cardiac nervous activity using 123I-MIBG scintigraphy may be a promising tool to determine of effectiveness of the cardiac radiofrequency denervation. The study was supported by a grant from the Russian Science Foundation № 15-15-10016.

Evaluating the optimum rest period prior to blood collection for fractionated plasma free metanephrines analysis

IntroductionThe high diagnostic accuracy of plasma metanephrines (PMets) in the diagnosis of Phaeochromocytoma/Paraganglioma (PPGL) is well established. Considerable controversy exists regarding optimum sampling conditions for PMets. The use of reference intervals that do not compromise diagnostic sensitivity is recommended. However, the optimum rest period prior to sampling has yet to be clearly established. The aim of this study was to evaluate PMets concentrations in paired blood samples collected following 30 and 40min seated-rest prior to sampling, in patients in whom it was clinically reasonable to suspect that PPGL may be present. Design and MethodsA retrospective cross-sectional study design was used. PMets results from paired blood samples collected after 30 and 40min seated-rest between January 2009 and June 2015 were recorded. Results were interpreted using reference intervals established in subjects seated and supine. ResultsA total of 410 patient results were eligible for analysis. There was no statistical difference between plasma normetanephrine (NMN) or metanephrine (MN) concentrations in samples collected following 30 and 40min seated-rest in subjects with PPGL (n=11), post-resection of PPGL (n=20) or in whom PPGL was excluded (n=379). Using reference intervals established in the seated position, diagnostic sensitivity was 100% at 30min and 90.9% at 40min. Diagnostic specificity was approximately 95% at both time points. When supine reference intervals were used, diagnostic sensitivity was 100% and diagnostic specificity was reduced by ≈22% at both time points. ConclusionBased on these data, we recommend at most 30min continuous rest prior to sampling for PMets measurement.

Is Biochemical Assessment of Pheochromocytoma Necessary in Adrenal Incidentalomas with Magnetic Resonance Imaging Features not Suggestive of Pheochromocytoma?

Currently, it is unclear whether pheochromocytomas can be ruled out based on low intensity on T2-weighted sequences and signal loss on out-of-phase magnetic resonance imaging (MRI) sequences. Hence, in this study, we investigated whether biochemical screening for pheochromocytoma in patients with adrenal incidentalomas (AIs) showing MRI features not suggesting pheochromocytoma would prove beneficial. We performed MRI for 300 AIs in 278 consecutive patients. All patients were screened for pheochromocytoma with plasma metanephrine and normetanephrine. Patients with high plasma levels of metanephrine and/or normetanephrine were also assessed for pheochromocytoma by urinary metanephrines. Hyperintensity was detected on T2-weighted MRI sequences in 28 (9.3%) of the 300 AIs. Among these 28 incidentalomas, pheochromocytoma was diagnosed in 13 (46.4%) of the cases by histopathologic analysis. Hyperintensity on T2-weighted MRI was significantly higher in pheochromocytomas compared to the remaining AIs (P<.001). All 13 pheochromocytomas were characterized by hyperintensity on T2-weighted sequences and the absence of signal loss on out-of-phase MRI sequences. Pheochromocytoma was not detected in any of the 272 AIs that appeared hypointense or isointense on T2-weighted MRI sequences or in the 250 cases with signal loss on out-of-phase sequences. The results of this study suggest that AIs that appear hypointense or isointense on T2-weighted MRI sequences and those with signal loss on out-of-phase sequences may not require routine biochemical screening for pheochromocytoma. Further studies including a higher number of pheochromocytomas are required to confirm our results.

Clinical case of rheumatoid arthritis with antiphospholipid antibody syndrome

The article presents a clinical case of development of secondary antiphospholipid syndrome (APS) with early active rheumatoid polyarthritis, complication in the form of acute deep vein thrombosis of forearm on the left and chronic left vein thrombosis of the lower extremity. Patient treatment with methotrexate has developed an infectious complication and resulting in the need to go to therapy of leflunomide. This therapy have positive effect. In a survey of the patient revealed a rare form of adrenal pheochromocytoma confirmed by computed tomography and measurements of plasma normetanephrine, but not accompanied an increase of blood pressure. This article discusses the modern classification of APS, pathogenesis, clinical and laboratory diagnostic criteria, methods of therapy as rheumatoid arthritis, and APS.

Validation of an assay for quantification of free normetanephrine, metanephrine and methoxytyramine in plasma by high performance liquid chromatography with coulometric detection: Comparison of peak-area vs. peak-height measurements.

Measurements of plasma concentrations of free normetanephrine (NMN), metanephrine (MN) and methoxytyramine (MTY) constitute the most diagnostically accurate screening test for pheochromocytomas and paragangliomas. The aim of this article is to present the results from a validation of an analytical method utilizing high performance liquid chromatography with coulometric detection (HPLC-CD) for quantifying plasma free NMN, MN and MTY. Additionally, peak integration by height and area and the use of one calibration curve for all batches or individual calibration curve for each batch of samples was explored as to determine the optimal approach with regard to accuracy and precision. The method was validated using charcoal stripped plasma spiked with solutions of NMN, MN, MTY and internal standard (4-hydroxy-3-methoxybenzylamine) with the exception of selectivity which was evaluated by analysis of real plasma samples. Calibration curve performance, accuracy, precision and recovery were determined following both peak-area and peak-height measurements and the obtained results were compared. The most accurate and precise method of calibration was evaluated by analyzing quality control samples at three concentration levels in 30 analytical runs. The detector response was linear over the entire tested concentration range from 10 to 2000pg/mL with R(2)≥0.9988. The LLOQ was 10pg/mL for each analyte of interest. To improve accuracy for measurements at low concentrations, a weighted (1/amount) linear regression model was employed, which resulted in inaccuracies of -2.48 to 9.78% and 0.22 to 7.81% following peak-area and peak-height integration, respectively. The imprecisions ranged from 1.07 to 15.45% and from 0.70 to 11.65% for peak-area and peak-height measurements, respectively. The optimal approach to calibration was the one utilizing an individual calibration curve for each batch of samples and peak-height measurements. It was characterized by inaccuracies ranging from -3.39 to +3.27% and imprecisions from 2.17 to 13.57%. The established HPLC-CD method enables accurate and precise measurements of plasma free NMN, MN and MTY with reasonable selectivity. Preparing calibration curve based on peak-height measurements for each batch of samples yields optimal accuracy and precision.