Functional vagal paraganglioma developing 15 years after resection of a retroperitoneal paraganglioma

The patient, a 40-year-old woman, was diagnosed as having a functional right vagal paraganglioma (PGL) 15 years after undergoing resection for a retroperitoneal PGL. 123I-MIBG scintigraphy showed no accumulation, but as the blood noradrenaline and urinary normetanephrine concentrations were elevated, the tumor was judged as being functional, and surgery was scheduled. The patient was started on doxazosin infusion and embolization of the tumor feeding vessel was performed before the surgery. Intraoperative examination showed that the tumor was contiguous with the vagal nerve, necessitating combined resection of the vagal nerve with the tumor. Postoperatively, the catecholamine levels returned to normal range. Histopathologically, the tumor was diagnosed as a moderately differentiated, intermediate-malignant-grade PGL, with a GAPP score of 4 to 6. No non-chromaffin tissue was observed in the tumor background, so that the functional vagal PGL was considered as a sporadic metachronous tumor rather than as a metastasis from the retroperitoneal PGL. More than half of head and neck paragangliomas (HNPGLs) are reported to arise in the carotid body, and about 5% from the vagal nerve. In addition, HNPGLs rarely produce catecholamines. Herein, we consider the relationship with the previously resected retroperitoneal PGL based on a review of the literature.

24-hour urine metanephrine excretion in patients diagnosed with adrenal incidentaloma: impact of commonly used drugs on a clinical decision

INTRODUCTION

Incidentaloma is an adrenal tumor detected during diagnostic imaging performed for extra‑adrenal causes. Evaluation of metanephrine concentrations in a 24‑hour urine collection can be a significant challenge in patients with multiple medications and comorbidities.

OBJECTIVES

The aim of this study was to evaluate the effect of commonly used groups of drugs on metanephrine levels in the 24‑hour urine collection.

PATIENTS AND METHODS

A total of 1051 patients with adrenal mass below 10 Hounsfield units on unenhanced computed tomography were included in the study. Patients diagnosed with Cushing or Conn syndrome, adrenal carcinoma, pheochromocytoma, active extra‑adrenal malignant neoplasms, and exacerbation of severe illnesses were excluded. Metanephrine, normetanephrine, and 3‑methoxytyramine in the 24‑hour urine collection were measured by high‑performance liquid chromatography with electrochemical detection. Information on concomitant medication (β‑blockers, calcium channel blockers [CCBs], loop diuretics, thiazide diuretics, potassium‑sparing diuretics, α‑blockers, angiotensin‑converting enzyme inhibitors / angiotensin II receptor blockers, metformin, nonmetformin antidiabetic drugs [NMADs], lipid‑lowering drugs, proton pump inhibitors, levothyroxine, thyreostatics, antidepressants, neuroleptics, benzodiazepines, glucocorticosteroids, inhaled B‑receptor agonists, and ipratropium) was collected from each patient.

RESULTS

The urinary excretion of normetanephrine was significantly higher in the patients on β‑blockers, CCBs, loop diuretics, α‑blockers, NMADs, and neuroleptics. α‑Blockers increased urine metanephrine concentration, and NMADs, antidepressants, and glucocorticosteroids lowered it. There was no association between the analyzed drugs and urinary 3‑methoxytyramine level.

CONCLUSIONS

Many drug groups interfere with the measurement of urinary fractionated metanephrines. These interactions should be taken into account during interpretation of a hormonal evaluation, as they can be crucial for further management, especially for making a decision on surgical treatment.

Dual-Template Magnetic Molecularly Imprinted Polymer for Simultaneous Determination of Spot Urine Metanephrines and 3-Methoxytyramine for the Diagnosis of Pheochromocytomas and Paragangliomas

A novel dual-template magnetic molecularly imprinted polymer (MMIP) was synthesized to extract normetanephrine (NMN), metanephrine (MN) and 3-methoxytyramine (3-MT) from spot urine samples. As the adsorbent of dispersive solid-phase extraction (d-SPE), the MMIP was prepared using dopamine and MN as dual templates, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the crosslinking reagent and magnetic nanoparticles as the magnetic core. NMN, MN, 3-MT and creatinine (Cr) in spot urine samples were selectively enriched by d-SPE and detected by HPLC-fluorescence detection/ultraviolet detection. The peak area (A) ratios of NMN, MN and 3-MT to Cr were used for the diagnosis of pheochromocytomas and paragangliomas (PPGLs). The results showed that the adsorption efficiencies of MMIP for target analytes were all higher than 89.0%, and the coefficient variation precisions of intra-assay and inter-assay for the analytes were within 4.9% and 6.3%, respectively. The recoveries of the analytes were from 93.2% to 112.8%. The MMIP was still functional within 14 days and could be reused at least seven times. The d-SPE and recommended solid-phase extraction (SPE) were both used to pretreat spot urine samples from 18 PPGLs patients and 22 healthy controls. The correlation coefficients of A_NMN/A_Cr and A_MN/A_Cr between d-SPE and SPE were both higher than 0.95. In addition, the areas under the receiver operator curves for spot urine A_NMN/A_Cr, A_MN/A_Cr and plasma free NMN and MN were 0.975, 0.773 and 0.990, 0.821, respectively, indicating the two methods had the similar performances. The d-SPE method took only 20 min, which was effective in clinical application.

Multivariate Statistical Approach for Nephrines in Women with Obesity

Catecholamines are physiological regulators of carbohydrate and lipid metabolism during stress, but their chronic influence on metabolic changes in obese patients is still not clarified. The present study aimed to establish the associations between the catecholamine metabolites and metabolic syndrome (MS) components in obese women as well as to reveal the possible hidden subgroups of patients through hierarchical cluster analysis and principal component analysis. The 24-h urine excretion of metanephrine and normetanephrine was investigated in 150 obese women (54 non diabetic without MS, 70 non-diabetic with MS and 26 with type 2 diabetes). The interrelations between carbohydrate disturbances, metabolic syndrome components and stress response hormones were studied. Exploratory data analysis was used to determine different patterns of similarities among the patients. Normetanephrine concentrations were significantly increased in postmenopausal patients and in women with morbid obesity, type 2 diabetes, and hypertension but not with prediabetes. Both metanephrine and normetanephrine levels were positively associated with glucose concentrations one hour after glucose load irrespectively of the insulin levels. The exploratory data analysis showed different risk subgroups among the investigated obese women. The development of predictive tools that include not only traditional metabolic risk factors, but also markers of stress response systems might help for specific risk estimation in obesity patients.

Random 'spot' urinary metanephrines compared with 24-h-urinary and plasma results in phaeochromocytomas and paragangliomas

BACKGROUND

In patients with phaeochromocytomas or paragangliomas (PPGLs), 24-h urine collections for metanephrines (uMNs) are cumbersome.

OBJECTIVE

To evaluate the diagnostic utility of ratios to creatinine of 'spot' uMNs.

METHODS

Concentrations of uMNs and plasma metanephrines (pMNs) were measured by HPLC-mass-spectrometry. We retrospectively compared correlations of 24-h-urine output and ratio to creatinine in historical specimens and prospectively assessed 24-h and contemporaneous spot urines and, where possible, pMNs. Using trimmed log-transformed values, we derived reference intervals based on age and sex for spot urines. We used multiples of upper limit of normal (ULNs) to compare areas under curves (AUCs) for receiver-operator characteristic curves of individual, and sum and product of, components.

RESULTS

In 3143 24-h-urine specimens on 2416 patients, the correlation coefficients between the ratios and outputs of metanephrine, normetanephrine and 3-methoxytyramine in 24-h urines were 0.983, 0.905 and 0.875, respectively. In 96 patients, the correlations between plasma concentrations, urine output and ratios in spot specimens were similar to those for raw output or ratios in 24-h specimens. Of the 160 patients with PPGLs, the CIs for AUCs for individual metabolites overlapped for all four types of measurement, as did those for the sum of the multiple ULNs although these were slightly higher (AUC for spot urine: 0.838 (0.529-1), plasma: 0.929 (0.874-0.984) and output: 0.858 (0.764-0.952)).

CONCLUSIONS

Ratios of fractionated metanephrines to creatinine in spot urine samples appear to have a similar diagnostic power to other measurements. The ease of spot urine collection may facilitate diagnosis and follow-up of PPGLs through improved patient compliance.

Association between higher urinary normetanephrine and insulin resistance in a Japanese population

Since activation of the sympathetic nervous system is associated with both impaired insulin secretion and insulin resistance, or namely with diabetes, evaluation of such activation in ordinary clinical settings may be important. Therefore, we evaluated the relationships between urinary concentrations of the catecholamine metabolites, urinary normetanephrine (U-NM) and urinary metanephrine (U-M), and glucose metabolism in a general population. From 1,148 participants in the 2016 population-based Iwaki study of Japanese, enrolled were 733 individuals (gender (M/F): 320/413; age: 52.1±15.1), who were not on medication affecting serum catecholamines, not diabetic, and had complete data-set and blood glucose levels appropriate for the evaluation of insulin secretion and resistance, using homeostasis model assessment (HOMA-β and HOMA-R, respectively). Univariate linear regression analyses revealed significant correlations between both U-NM and U-M, and HOMA-β, but adjustment for multiple factors correlated with HOMA indices abolished these (β = -0.031, p = 0.499, and β = -0.055, p = 0.135, respectively). However, the correlation between U-NM and HOMA-R observed using univariate linear regression analysis (β = 0.132, p<0.001) remained significant even after these adjustments (β = 0.107, p = 0.007), whereas U-M did not correlate with HOMA-R. Furthermore, use of the optimal cut-off value of U-NM for the prediction of insulin resistance (HOMA-R >1.6) determined by ROC analysis (0.2577 mg/gCr) showed that individuals at risk had an odds ratio of 2.65 (confidence interval: 1.42–4.97) after adjustment for the same factors used above. Higher U-NM concentrations within the physiologic range are a significant risk factor for increased insulin resistance in a general Japanese population.

Correlation between urinary fractionated metanephrines in 24-hour and spot urine samples for evaluating the therapeutic effect of metyrosine: a subanalysis of a multicenter, open-label phase I/II study

We recently conducted an open-label phase I/II study to evaluate the efficacy and safety of preoperative and chronic treatment with metyrosine (an inhibitor of catecholamine synthesis) in pheochromocytoma/paraganglioma (PPGL) in Japan. We compared creatinine-corrected metanephrine fractions in spot urine and 24-hour urine samples (the current standard for the screening and diagnosis of PPGLs) from 16 patients to assess the therapeutic effect of metyrosine. Percent changes from baseline in urinary metanephrine (uMN) or normetanephrine (uNMN) were compared between spot and 24-hour urine samples. Mean percent changes in uMN or uNMN in spot and 24-hour urine were -26.36% and -29.27%, respectively. The difference in the percent change from baseline between uMN or uNMN in spot and 24-hour urine was small (-2.90%). The correlation coefficient was 0.87 for percent changes from baseline between uMN or uNMN measured in spot and 24-hour urine. The area under the receiver operator characteristic (ROC) curve of uMN or uNMN measured in spot urine vs. 24-hour urine (reference standard) to assess the efficacy of metyrosine treatment was 0.93. Correlations and ROCs between 24-hour urinary vanillylmandelic acid, adrenaline, and noradrenaline and 24-hour uMN or uNMN were similar to those between spot uMN or uNMN and 24-hour uMN or uNMN. No large difference was observed between spot and 24-hour urine for the assessment of metyrosine treatment by quantifying uMN or uNMN in Japanese patients with PPGLs. These results suggest that spot urine samples may be useful in assessing the therapeutic effect of metyrosine.

Change of skeletal muscle mass in patients with pheochromocytoma

The effects of catecholamine excess due to pheochromocytoma on body composition, including skeletal muscle mass, are unknown. Here, we investigated the effects of catecholamine metabolites on body composition in subjects with pheochromocytoma. After body compositions using bioelectrical impedance analysis, urinary metanephrine (UM), and urinary normetanephrine (UNM) were measured in 16 patients with pheochromocytoma and 224 patients with nonfunctioning adrenal incidentaloma (NFAI), we compared skeletal muscle mass and fat mass (FM) between the two groups. After adjustments for confounders, UM (β = - 0.171, P = 0.006) and UNM (β = - 0.249, P < 0.001) levels were correlated inversely with skeletal muscle mass index (SMI), but not FM or percentage FM (pFM), in all subjects. Patients with pheochromocytoma had lower ASM by 7.7% (P = 0.022) and SMI by 6.6% (P = 0.001) than patients with NFAI. Conversely, FM and pFM were not statistically different between the two groups. The odds ratio for low skeletal muscle mass in the presence of pheochromocytoma was 10.33 (95% confidence interval, 2.65-40.22). Our results indicate that patients with pheochromocytoma have a reduced skeletal muscle mass and suggest that catecholamine excess has adverse effects on skeletal muscle metabolism.

Differences in the actions of adrenaline and noradrenaline with regard to glucose intolerance in patients with pheochromocytoma

Glucose intolerance is often observed in patients with pheochromocytoma. However, it remains controversial issue that glucose intolerance on pheochromocytoma is caused by impaired insulin secretion and/or by increased insulin resistance. We aimed to reveal the mechanism of glucose intolerance on pheochromocytoma with regard to the type and amount of catecholamines released. We evaluated 12 individuals diagnosed with pheochromocytoma and who underwent surgery to remove it. We examined glycemic parameters before and after surgery and investigated the association between the change of parameters of insulin secretion (homeostasis model assessment of β-cell function (HOMA-β)), insulin resistance (homeostasis model assessment of insulin resistance (HOMA-IR)) and that of urinary levels of metanephrine/normetanephrine before and after surgery. Overall, fasting plasma glucose, glycated hemoglobin (HbA1c), HOMA-β, and HOMA-IR were improved significantly after surgery. Regression analysis showed that the improvement in HOMA-β from before to after surgery was significantly positively associated with an improvement in urinary levels of metanephrine from before to after surgery and showed a significantly negative association with improvement in urinary levels of normetanephrine from before to after surgery. The improvement in HOMA-IR from before to after surgery was significantly positively associated with an improvement in urinary levels of normetanephrine from before to after surgery. Our results showed that pheochromocytoma extirpation improved glycemic parameters. Furthermore, the different effects elicited by excess amounts of adrenaline and noradrenaline on glucose intolerance were demonstrated.

Reference intervals for LC-MS/MS measurements of plasma free, urinary free and urinary acid-hydrolyzed deconjugated normetanephrine, metanephrine and methoxytyramine

BACKGROUND

Plasma or urinary metanephrines are recommended for screening of pheochromocytomas and paragangliomas (PPGLs). Measurements of urinary free rather than deconjugated metanephrines and additional measurements of methoxytyramine represent other developments. For all measurements there is need for reference intervals.

METHODS

Plasma free, urinary free and urinary deconjugated O-methylated catecholamine metabolites were measured by LC-MS/MS in specimens from 590 hypertensives and normotensives. Reference intervals were optimized using data from 2,056 patients tested for PPGLs.

RESULTS

Multivariate analyses, correcting for age and body surface area, indicated higher plasma and urinary metanephrine in males than females and sex differences in urinary normetanephrine and free methoxytyramine that largely reflected body size variation. There were positive associations of age with plasma metabolites, but negative relationships with urinary free metanephrine and methoxytyramine. Plasma and urinary normetanephrine were higher in hypertensives than normotensives, but differences were small. Optimization of reference intervals using the data from patients tested for PPGLs indicated that age was the most important consideration for plasma normetanephrine and sex most practical for urinary metabolites.

CONCLUSION

This study clarifies impacts of demographic and anthropometric variables on catecholamine metabolites, verifies use of age-specific reference intervals for plasma normetanephrine and establishes sex-specific reference intervals for urinary metabolites.

Higher sympathetic activity as a risk factor for skeletal deterioration in pheochromocytoma

Despite the potential biological importance of sympathetic activity in human bone metabolism, its effects on bone microarchitecture, a key determinant of bone quality, has not been thoroughly studied. In the present study, we investigated the lumbar spine trabecular bone score (TBS) as an indicator of skeletal deterioration in pheochromocytoma. Among 620 consecutive patients with newly diagnosed adrenal incidentaloma, 29 with histologically confirmed pheochromocytoma (a catecholamine-secreting neuroendocrine tumor) and 266 with nonfunctional adrenal incidentaloma were defined as cases and controls, respectively. After adjustment for confounders, subjects with pheochromocytoma had 2.9% lower lumbar spine TBS than those without pheochromocytoma (P = 0.038). Moreover, urinary normetanephrine level, but not urinary metanephrine level, was inversely correlated with lumbar spine TBS (P = 0.009). Subjects in the highest urinary normetanephrine quartile showed markedly lower lumbar spine TBS than those in the lowest quartile (P = 0.018), in a dose-response manner across increasing urinary normetanephrine quartile categories (P for trend = 0.021). Consistent with the results of previous studies, subjects with pheochromocytoma had significantly lower bone mass at the lumbar spine and higher serum level of C-terminal telopeptide of type I collagen than controls (P = 0.013 and 0.002, respectively). These findings provide clinical evidence that catecholamine excess and the resultant sympathetic overstimulation in pheochromocytoma may contribute to bone fragility, especially in the trabecular bone, through a weak microarchitecture in addition to a lower bone mass and increased bone resorption, and support the possibility of pheochromocytoma as a secondary cause of osteoporosis.

Next-generation panel sequencing identifies NF1 germline mutations in three patients with pheochromocytoma but no clinical diagnosis of neurofibromatosis type 1

OBJECTIVE

Our objective was to improve molecular diagnostics in patients with hereditary pheochromocytoma and paraganglioma (PPGL) by using next-generation sequencing (NGS) multi-gene panel analysis. Derived from this study, we here present three cases that were diagnosed with NF1 germline mutations but did not have a prior clinical diagnosis of neurofibromatosis type 1 (NF1).

DESIGN

We performed genetic analysis of known tumor predisposition genes, including NF1, using a multi-gene NGS enrichment-based panel applied to a total of 1029 PPGL patients. We did not exclude genes known to cause clinically defined syndromes such as NF1 based on missing phenotypic expression as is commonly practiced.

METHODS

Genetic analysis was performed using NGS (TruSight Cancer Panel/customized panel by Illumina) for analyzing patients' blood and tumor samples. Validation was carried out by Sanger sequencing.

RESULTS

Within our cohort, three patients, who were identified to carry pathogenic NF1 germline mutations, attracted attention, since none of the patients had a clinical suspicion of NF1 and one of them was initially suspected to have MEN2A syndrome due to co-occurrence of a medullary thyroid carcinoma. In these cases, one splice site, one stop and one frameshift mutation in NF1 were identified.

CONCLUSIONS

Since phenotypical presentation of NF1 is highly variable, we suggest analysis of the NF1 gene also in PPGL patients who do not meet diagnostic NF1 criteria. Co-occurrence of medullary thyroid carcinoma and PPGL was found to be a clinical decoy in NF1 diagnostics. These observations underline the value of multi-gene panel NGS for PPGL patients.

Symptom-dependent cut-offs of urine metanephrines improve diagnostic accuracy for detecting pheochromocytomas in two separate cohorts, compared to symptom-independent cut-offs

The development of advanced imaging techniques has increased the detection of subclinical pheochromocytomas. Because of the substantial proportions of subclinical pheochromocytomas, measurement of urine metanephrine concentrations is crucial due to detect or exclude pheochromocytoma. Although urine metanephrines are elevated in symptomatic subjects, diagnostic cut-offs according to the presence of adrenergic symptoms have not been studied. Pheochromocytomas patients who underwent adrenalectomy at Samsung Medical Center and a control group were compared to determine cut-off concentrations of urine metanephrines. An independent population was analyzed for urine metanephrines with different kits to validate the improvement in diagnostic accuracy using adjusted cut-offs. Symptom-dependent cut-offs of urine metanephrines were higher for symptomatic patients (307 μg/day in males, 235 μg/day in females for urine metanephrine, and 1,045 μg/day in males and 457 μg/day in females for urine normetanephrine) than for asymptomatic patients (206 μg/day in males, 199 μg/day in females for urine metanephrine, and 489 μg/day in males and 442 μg/day in females for urine normetanephrine). Symptom-dependent cut-offs of urine metanephrines improved a specificity from 92.7 % to 96.3 % and a high sensitivity of 97.8 % was maintained. Using the Symptom-dependent cut-offs raised diagnostic accuracy by 5.5 % (p <0.001). Similar trend was also observed in an independent population using different hormone kits. Using symptom-dependent cut-offs of urine metanephrines in symptomatic patients for pheochromocytomas resulted in a significant improvement in diagnostic accuracy in two separate cohorts.

Parkinson's disease: the effect of L-dopa therapy on urinary free catecholamines and metabolites

Background: L-dopa is an important antiparkinsonian drug. It is a precursor of dopamine and the other catecholamines. Potentially, administration of L-dopa could lead to increased urinary excretion of catecholamines and their metabolites to abnormal amounts. The current study aimed to determine these excretions in patients with Parkinson's disease (PD) receiving L-dopa compared with suitable controls. This is the first assessment of the effect of exogenous administration of L-dopa on urinary free metadrenalines.

Methods: Using one-way analysis of variance (ANOVA), urine catecholamines and metabolites, expressed as mmol per mole creatinine, were compared in: patients with PD who were receiving L-dopa; patients with PD but not receiving L-dopa; and patients without PD who were being investigated for the presence of phaechromocytoma but were found not to have the disease.

Results: Significantly higher values for urinary dopamine, homovanillic acid, free normetadrenaline and free metadrenaline were found in patients with PD receiving L-dopa compared with the other two control groups. In all the patients with PD, these four analytes were significantly correlated with daily dose of L-dopa.

Conclusion: L-dopa therapy can result in production of false positives for urinary excretion of dopamine, homovanillic acid, free normetadrenaline or free metadrenaline and thereby decrease the diagnostic value of these measurements in identifying phaeochromocytoma and related tumours.

Paracetamol-associated interference in an HPLC-ECD assay for urinary free metadrenalines and catecholamines

Background: Some high-performance liquid chromatography techniques with electrochemical detection for urinary catecholamines and their metabolites can be subject to interference from drugs and their metabolites. Prime amongst these interferences are those due to paracetamol ingestion.

Methods: The prevalence of paracetamol contamination was determined by measuring the drug in all patient specimens submitted for catecholamine analysis over a 2-month period. These findings were then related to the proportion of unreportable results at each range of specimen paracetamol concentration. The apparent results from a small representative sample of the paracetamol-positive specimens are illustrated.

Results: Approximately one-third of urine specimens were found to contain paracetamol. Low-level contamination can produce apparent patterns of results which may easily be confused with those found in predominantly adrenaline-, or metadrenaline-secreting phaeochromocytomas.

Conclusion: Despite the fact that significantly less than 5% of an oral dose of paracetamol is excreted as the free drug, its analysis provides a good surrogate marker for the likelihood of spurious results. It is useful to know prior to urinary free metadrenaline or catecholamine analysis which urine specimens are likely to contain potentially interfering paracetamol metabolites.

Retroperitoneal Functioning Paraganglioma--A Rare Case of Secondary Diabetes

INTRODUCTION

Paragangliomas are rare neuroendocrine tumors that arise from the extra-adrenal autonomic paraganglia, which can derive from either parasympathetic or sympathetic paraganglia and are closely related to pheochromocytomas.

CASE REPORT

We present the case of a young male patient of 37 years old, who was admitted for hypertensive crisis and palpitations. His medical history included medically controlled type 2 diabetes mellitus, (diagnosed 10 months ago), Hepatitis A. Hormonal evaluation revealed elevated urinary metanephrines and normetanephrines, with mainly increased normetanephrines (2330 ug/24 h). Plasmatic metanephrins were in normal range, but levels of plasmatic normetanephrins were elevated (952 pg/ml). The assessment of pituitary and aldosterone-renin axis values were within normal limits. Abdominal computed tomography showed left adrenal nodular lesion on the external arm, bilobulated, size 32/33 mm with maximum axial and cranio-caudal diameter of approx. 45 cm, suggestive of a benign lesion, keeping the cleavage plane to vecinatate structures. Left adrenalectomy was performed by laparoscopic approach. We mention that immediately after induction of anesthesia were recorded blood pressures of 298/143 mmHg. Histopathologic and immunohistochemical examination diagnose paraganglioma, without invasion of adjacent tissues. The patient evolution was favorable, with the remission of the symptoms and normalization of hormonal markers. It is imperative to note the remission of diabetes in the postoperative period.

DISCUSSION

This is the case of a young patient with functional retroperitoneal paraganglioma, who presented with symptoms of pheochromocytoma. Compared to pheochromocytomas, paragangliomas are rarely symptomatic and functional. Association with diabetes is even more rare. Specialized investigations allowed the proper diagnosis and the therapeutic approach above was the result of a multidisciplinary cooperation.

Quantification of Metanephrine and Normetanephrine in Urine Using Liquid Chromatography-Tandem Mass Spectrometry

Measuring urinary metanephrines aides in the diagnosis of pheochromocytomas-catecholamine producing tumors. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) allows for greater sensitivity and simpler sample preparation as compared with other techniques. Here we describe a simple LC-MS/MS method for measuring metanephrines in urine. Each urine sample was treated with diphenylboronic acid to create boronate complexes, and then applied to a Bond-Elut Plexa cartridge. After solid phase extraction, samples were concentrated and analyzed on an Atlantis T3 column with chromatographic run time totaling 8.5 min. MS/MS was set in positive electrospray ionization mode with multiple reaction monitoring for data collection. The assay was linear from 0.2 to 27.4 μmol/L and 0.3 to 14.6 μmol/L for metanephrine and normetanephrine, respectively. Intra-assay and total precision at three concentration levels over 10 days were <5 % for metanephrine and <10 % for normetanephrine.

[THE SIMULTANEOUS ANALYSIS OF FREE CATECHOLAMINES AND METANEPHRTNES IN URINE USING TECHNIQUE OF HIGHLY EFFECTIVE LIQUID CHROMATOGRAPHY WITH FLUORIMETRIC DETECTION AND SOLID PHASE EXTRACTION ON POLYMERIC SORBENT (PUROSEP-200)]

The article considers the technique of simultaneous detection of free catecholamines and free metanephrines in urine using inverse phase highly effective liquid chromatography with fluorimetric detection. The solid phase extraction was implemented on cartridges with 30 mg of hyper cross-linked polystyrene (Purosep-200). The simplicity, reproducibility and sufficient sensitivity of technique permit applying it in clinical practice to diagnose pheochromocytoma.

Catecholamine-Synthesizing Enzymes Are Expressed in Parasympathetic Head and Neck Paraganglioma Tissue

BACKGROUND/AIM

Increased dopamine production may be a feature of head and neck paraganglioma (HNPGL). 18F-fluorodihydroxyphenylalanine positron emission tomography scintigraphy has a high sensitivity for detecting HNPGLs. These observations strongly suggest that HNPGLs have the capacity for L-3,4-dihydroxyphenylalanine uptake and conversion towards dopamine. Therefore, our aim was to demonstrate the presence of catecholamine-synthesizing enzymes, i.e. tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AADC) and dopamine β-hydroxylase (DBH) in HNPGL tissue.

METHODS

A single-center study was performed among patients who underwent surgery for HNPGL at a single university referral center between 1994 and 2012. HNPGL tissue was immunohistochemically stained for TH, AADC and DBH. Data on paraganglioma-associated germline mutations, preoperative biochemical phenotype and imaging studies were retrieved. Catecholamine excess was defined as preoperative plasma and/or urinary levels of metanephrine, normetanephrine or 3-methoxytyramine above the upper reference limit.

RESULTS

Nineteen HNPGLs from 18 patients were evaluated. All tumor tissues (100%) stained positive for AADC, 6 (32%) for TH and 2 (11%) for DBH. Of 3 HNPGLs staining positive for DBH, 2 were also positive for AADC and TH. Catecholamine excess was only present in 1 patient (5%). The HNPGLs of this single patient only showed positive staining for AADC.

CONCLUSIONS

Catecholamine-synthesizing enzymes, in particular AADC, are expressed in the majority of HNPGL tissues.

Biochemical and radiological relationships in patients with pheochromocytoma: lessons from a case control study

BACKGROUND

An elevation of fractionated plasma or urinary metanephrine (MN) or nor-metanephrine (NMN), collectively called metanephrines (MN and NMN), >4-fold above the upper limit of normal (ULN) is usually considered to be diagnostic for pheochromocytoma (PHEO). There are a greater number of false positive results when the elevations are more modest.

AIM

To identify biochemical and radiological features in PHEOs with modest elevations (<4-fold above ULN) of metanephrines.

METHODOLOGY

We retrospectively reviewed the charts of 112 patients with PHEO (10% extra-adrenal) and 208 patients with a non-PHEO adrenal mass operated from 1997-2011, who had metanephrines measured pre-operatively. We divided PHEO into group 1 (n = 90) with metanephrines ≥4-fold ULN and group 2 (n = 22) with metanephrines <4-fold ULN. The non-PHEO group was designated as group 3.

RESULTS

The median (range) tumour size in group 1 and group 2 was 4·8 cm (1·7-22) and 3·0 cm (1·7-5) respectively (P < 0·001). All patients with PHEO in group 2 had a tumour <5 cm in size. The MN fraction was elevated in about 65% of groups 1 and 2; only 2 (1%) patients in group 3 had an elevated urinary MN fraction, and none were associated with an elevated plasma MN fraction. All PHEOs had a pre-contrast attenuation ≥17 Hounsfield Units (HU).

CONCLUSIONS

Modest elevations (<4-fold ULN) of the NMN fraction in an adrenal mass >5 cm are almost always falsely positive. Elevations in plasma and urinary MN fraction are less likely to be false positive. The CT pre-contrast attenuation of PHEOs is >10 HU.

Biochemical diagnosis of phaeochromocytoma using plasma-free normetanephrine, metanephrine and methoxytyramine: importance of supine sampling under fasting conditions

OBJECTIVE

To document the influences of blood sampling under supine fasting versus seated nonfasting conditions on diagnosis of phaeochromocytomas and paragangliomas (PPGL) using plasma concentrations of normetanephrine, metanephrine and methoxytyramine.

DESIGN AND METHODS

Biochemical testing for PPGL was performed on 762 patients at six centres, two of which complied with requirements for supine sampling after an overnight fast and four of which did not. Phaeochromocytomas and paragangliomas were found in 129 patients (67 noncompliant, 62 compliant) and not in 633 patients (195 noncompliant, 438 compliant).

RESULTS

Plasma concentrations of normetanephrine and methoxytyramine did not differ between compliant and noncompliant sampling conditions in patients with PPGL but were 49-51% higher in patients without PPGL sampled under noncompliant compared with compliant conditions. The 97·5 percentiles of distributions were also higher under noncompliant compared with compliant conditions for normetanephrine (1·29 vs 0·79 nmol/l), metanephrine (0·49 vs 0·41 nmol/l) and methoxytyramine (0·42 vs 0·18 nmol/l). Use of upper cut-offs established from seated nonfasting sampling conditions resulted in substantially decreased diagnostic sensitivity (98% vs 85%). In contrast, use of upper cut-offs established from supine fasting conditions resulted in decreased diagnostic specificity for testing under noncompliant compared with compliant conditions (71% vs 95%).

CONCLUSIONS

High diagnostic sensitivity of plasma normetanephrine, metanephrine and methoxytyramine for the detection of PPGL can only be guaranteed using upper cut-offs of reference intervals established with blood sampling under supine fasting conditions. With such cut-offs, sampling under seated nonfasting conditions can lead to a 5·7-fold increase in false-positive results necessitating repeat sampling under supine fasting conditions.

Diagnosis of endocrine disease: Biochemical diagnosis of phaeochromocytoma and paraganglioma

Adrenal phaechromocytomas and extra-adrenal sympathetic paragangliomas (PPGLs) are rare neuroendocrine tumours, characterised by production of the catecholamines: noradrenaline, adrenaline and dopamine. Tumoural secretion of catecholamines determines their clinical presentation which is highly variable among patients. Up to 10-15% of patients present entirely asymptomatic and in 5% of all adrenal incidentalomas a PPGL is found. Therefore, prompt diagnosis of PPGL remains a challenge for every clinician. Early consideration of the presence of a PPGL is of utmost importance, because missing the diagnosis can be devastating due to potential lethal cardiovascular complications of disease. First step in diagnosis is proper biochemical analysis to confirm or refute the presence of excess production of catecholamines or their metabolites. Biochemical testing is not only indicated in symptomatic patients but also in asymptomatic patients with adrenal incidentalomas or identified genetic predispositions. Measurements of metanephrines in plasma or urine offer the best diagnostic performance and are the tests of first choice. Paying attention to sampling conditions, patient preparation and use of interfering medications is important, as these factors can largely influence test results. When initial test results are inconclusive, additional tests can be performed, such as the clonidine suppression test. Test results can also be used for estimation of tumour size or prediction of tumour location and underlying genotype. Furthermore, tumoural production of 3-methoxytyramine is associated with presence of an underlying SDHB mutation and may be a biomarker of malignancy.

Plasma free metanephrines in the diagnosis of pheochromocytoma: diagnostic accuracy and strategies for Japanese patients

Measuring the levels of the plasma free metanephrines (PFMs) represents a recently developed and promising test for the diagnosis of pheochromocytoma in the United States and Europe. As this test has not yet been evaluated in Japan, it is necessary to evaluate the diagnostic efficacy of measuring the levels of PFMs compared with the standard measurement of the urinary excretion of metanephrines (uMNs) whose reliability is well established to detect of pheochromocytoma. A total of 101 Japanese subjects clinically suspected of having pheochromocytoma in were included in this study. Subsequently, we prospectively measured the PFMs levels in all patients, compared with those of biochemical markers of the catecholamine secretion and metabolisms in the plasma and urine. All subjects with adrenal tumors underwent tumor excision. Data were available for 84 of the 101 patients, 47 of whom had histopathologically proven pheochromocytoma and 37 were finally diagnosed with non-pheochromocytoma. The results of comparisons in the accuracy of measurement for diagnosis of pheochromocytoma between PFMs and the urinary excretion of metanephrines (uMNs) were 0.980 VS 0.951 for AUC of receiver operatorating characteristic (ROC) curve, 0.957 VS 0.894 for sensitivity, and 0.973 VS 0.946 for specificity, respectively. Although the differences were small, the results of our study definitely demonstrated that measurement of PFMs was not inferior to standard urinary metanephrines (uMNs) measurement, which is established to be the most reliable biochemical method to detect pheochromocytoma. This study clearly shows measuring the PFMs levels to be a reliable and efficient method for diagnosing pheochromocytoma in Japanese patients, as demonstrated in previous reports.

Levodopa therapy in Parkinson's disease: influence on liquid chromatographic tandem mass spectrometric-based measurements of plasma and urinary normetanephrine, metanephrine and methoxytyramine

BACKGROUND

Medication-related interferences with measurements of catecholamines and their metabolites represent important causes of false-positive results during diagnosis of phaeochromocytomas and paragangliomas (PPGLs). Such interferences are less troublesome with measurements by liquid chromatography with tandem mass-spectrometry (LC-MS/MS) than by other methods, but can still present problems for some drugs. Levodopa, the precursor for dopamine used in the treatment of Parkinson's disease, represents one potentially interfering medication.

METHODS

Plasma and urine samples, obtained from 20 Parkinsonian patients receiving levodopa, were analysed for concentrations of catecholamines and their O-methylated metabolites by LC-MS/MS. Results were compared with those from a group of 120 age-matched subjects and 18 patients with PPGLs.

RESULTS

Plasma and urinary free and deconjugated (free + conjugated) methoxytyramine, as well as urinary dopamine, showed 22- to 148-fold higher (P < 0.0001) concentrations in patients receiving levodopa than in the reference group. In contrast, plasma normetanephrine, urinary noradrenaline and urinary free and deconjugated normetanephrine concentrations were unaffected. Plasma free metanephrine, urinary adrenaline and urinary free and deconjugated metanephrine all showed higher (P < 0.05) concentrations in Parkinsonian patients than the reference group, but this was only a problem for adrenaline. Similar to normetanephrine, plasma and urinary metanephrine remained below the 97.5 percentiles of the reference group in almost all Parkinsonian patients.

CONCLUSIONS

These data establish that although levodopa treatment confounds identification of PPGLs that produce dopamine, the therapy is not a problem for use of LC-MS/MS measurements of plasma and urinary normetanephrine and metanephrine to diagnose more commonly encountered PPGLs that produce noradrenaline or adrenaline.

Unilateral and bilateral adrenalectomy for pheochromocytoma requires adjustment of urinary and plasma metanephrine reference ranges

CONTEXT

Follow-up after adrenalectomy for pheochromocytoma is recommended because of a recurrence risk. During follow-up, plasma and/or urinary metanephrine (MN) and normetanephrine (NMN) are interpreted using reference ranges obtained in healthy subjects.

OBJECTIVE

Because adrenalectomy may decrease epinephrine production, we compared MN and NMN concentrations in patients after adrenalectomy to concentrations in a healthy reference population.

DESIGN

A single-center cohort study was performed in pheochromocytoma patients after adrenalectomy between 1980 and 2011.

SUBJECTS

Seventy patients after unilateral and 24 after bilateral adrenalectomy were included.

MAIN OUTCOME MEASURES

Plasma-free and urinary-deconjugated MN and NMN determined at 3 to 6 months and annually until 5 years after adrenalectomy were compared with concentrations in a reference population. Data are presented in median (interquartile range).

RESULTS

Urinary and plasma MN concentrations 3 to 6 months after unilateral adrenalectomy were lower compared with the reference population (39 [31-53] μmol/mol creatinine and 0.14 [0.09-0.18] nmol/L vs 61 [49-74] μmol/mol creatinine and 0.18 [0.13-0.23] nmol/L, respectively, both P < .05). Urinary MN after bilateral adrenalectomy was reduced even further (7 [1-22] μmol/mol creatinine; P < .05). Urinary and plasma NMN were higher after unilateral adrenalectomy (151 [117-189] μmol/mol creatinine and 0.78 [0.59-1.00] nmol/L vs 114 [98-176] μmol/mol creatinine and 0.53 [0.41-0.70] nmol/L; both P < .05). Urinary NMN after bilateral adrenalectomy was higher (177 [106-238] μmol/mol creatinine; P < .05). Changes in urinary and plasma MNs persisted during follow-up.

CONCLUSION

Concentrations of MN are decreased, whereas NMN concentrations are increased after unilateral and bilateral adrenalectomy. Adjusted reference values for MN and NMN are needed in the postsurgical follow-up of pheochromocytoma patients.

Pheochromocytoma--analysis of 15 consecutive cases from one centre

INTRODUCTION

Pheochromocytoma is a rare tumour, but one of great clinical importance as a risk factor of malignancy, cardiovascular diseases and sudden death.

MATERIAL AND METHODS

15 consecutive patients (eight women and seven men) were hospitalised and submitted for adrenalectomy with pheochromocytoma confirmed by histopathologic examination. Adrenalectomies were performed laparoscopically in 14 cases (93.3%): in nine by the retroperitoneal posterior mode and in five by the transperitoneal lateral approach.

RESULTS

Molecular-genetic examination of VHL, RET, SDHB, SDHC and SDHD genes revealed inherited predisposition for PHEO in three of 15 patients (20%): RET mutations typical for MEN 2a in two patients and VHL mutation in one patient. Disturbances of the carbohydrate metabolism occurred in nine patients (60%). Ten patients (66%) reported paroxysmal symptoms. In all cases, with the exception of a von Hippel-Lindau patient, density of tumours exceeded 20 HU. In all studied patients, urine concentration of normetanephrines exceeded their normal range and greatly prevailed over metanephrines values, which were increased in six of them (40%).

CONCLUSIONS

Urine metoxycatecholamines and increased tissue density are sufficient in pheochromocytoma detection. However, taking into account clinical and supplemental biochemical data may be helpful in the diagnostic process. Laparoscopic adrenalectomy is a fully sufficient and safe method of pheochromocytoma excision.

Is biochemical screening for pheochromocytoma in adrenal incidentalomas expressing low unenhanced attenuation on computed tomography necessary?

OBJECTIVE

Pheochromocytomas are characterized by a high attenuation value on unenhanced computed tomography (CT). It is not known whether pheochromocytoma could be ruled out as a cause of adrenal incidentalomas on the basis of unenhanced attenuation values only.

DESIGN

We retrospectively evaluated the outcome of routine biochemical screening for pheochromocytoma in a series of adrenal incidentalomas in relationship to the unenhanced attenuation values on CT.

METHODS

An unenhanced CT was available in 174 of 184 patients with 214 adrenal incidentalomas. All patients were screened for pheochromocytoma with 24-h urinary metanephrines and normetanephrines and for hypercortisolism (1 mg dexamethasone test and ACTH). Hypertensive patients were screened for aldosterone overproduction (aldosterone to renin ratio and 24 h urinary aldosterone). The results were compared between incidentalomas with high [≥10 Hounsfield units (HU)] and low (<10 HU) unenhanced attenuation values.

RESULTS

One hundred forty-six incidentalomas in 115 patients had an unenhanced HU less than 10. None of these patients had elevated 24-h fractionated urinary metanephrines or normetanephrines suggesting pheochromocytoma. Sixty-eight incidentalomas in 59 patients had an unenhanced HU of 10 or greater, and nine (15.2%) of these patients had surgically and histologically verified pheochromocytoma. Incidentalomas with a HU of 10 or greater were significantly larger (2.6 ± 1.5 vs. 2.3 ± 1.2 cm; P < 0.001), more often functional (27.9 vs. 8.9%, P < 0.001), and more often operated (44.1 vs. 10.2%; P < 0.001) than those with a Hounsfield unit less than 10.

CONCLUSION

The results of this study indicate that routine biochemical screening of pheochromocytoma in small homogenous adrenal incidentalomas characterized by an unenhanced Hounsfield unit value less than 10 HU may not be necessary.

Different diagnostic cut-off values of urinary fractionated metanephrines according to sex for the diagnosis of pheochromocytoma in Korean subjects

The diagnosis of pheochromocytoma depends on the documentation of catecholamine overproduction. The use of urinary fractionated metanephrines has recently become common for the diagnosis of pheochromocytoma. In order to avoid false positive and false negative results, optimal cut-off levels are necessary; however, there have been few published reports on whether different cut-off levels are needed to diagnose pheochromocytoma according to sex. We reviewed the medical records of 815 subjects (including 103 pheochromocytoma patients) whose of 24-h urinary fractionated metanephrine was measured using high-performance liquid chromatography methods and adrenal imaging at Samsung Medical Center. Receiver operating characteristic (ROC) curves were used to determine cut-off values according to sex. The upper limit values of fractionated metanephrine in healthy volunteers and the control group were significantly higher in male subjects compared with females. When we applied cut-off values according to sex, the diagnostic efficacies (defining a positive test as either metanephrine or normetanephrine levels above the cut-off value) were a sensitivity of 96% in male subjects and 98.1% in female subjects and a specificity of 88.6% in male subjects and 94.1% in female subjects. However, when we applied cut-off values without considering sex, the specificity decreased from 88.6% to 77.8% in male subjects. In this study, urinary fractionated metanephrines had a high level of sensitivity and specificity for the diagnosis of pheochromocytoma. However, diagnostic cut-off values were higher in male subjects than in female subjects. Therefore, different cut-off values may be needed according to sex to diagnose pheochromocytoma in Koreans.

A patient with a large recurrent pheochromocytoma demonstrating the pitfalls of diagnosis

BACKGROUND

A 59-year-old man presented for a follow-up, 6 years after surgery for a large pheochromocytoma. He had suffered from diabetes mellitus, hypertension and abdominal pain in the right flank region. Previous postoperative follow-up did not reveal tumor recurrence.

INVESTIGATION

Measurement of plasma free metanephrine and normetanephrine by high-performance liquid chromatography and radioimmunoassay; 123I-metaiodobenzylguanidine (MIBG) scintigraphy; hybrid 123I-MIBG single-photon emission CT (SPECT)-CT; MRI; testing for plasma norepinephrine and epinephrine; intraoperative ultrasonography; histological staining for chromogranin A and synaptophysin; and postoperative 18F-dihydroxyphenylalanine (DOPA) PET scan.

DIAGNOSIS

Recurrent pheochromocytoma.

MANAGEMENT

Laparotomy with tumor resection. Reduction of antihypertensive medications. Further follow-up by MRI, hybrid 123I-MIBG SPECT-CT and testing for plasma catecholamines and free metanephrines.

A simple liquid chromatography-tandem mass spectrometry method for measuring metanephrine and normetanephrine in urine

BACKGROUND

Measuring urinary fractionated metanephrines is one of the initial tests in the diagnosis of pheochromocytoma. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) represents the most specific and accurate technology for this purpose. The goal of this work was to develop a simple LC-MS/MS method for measuring metanephrines in urine.

METHODS

Each urine sample was complexed with diphenylboronic acid, and purified on a Bond-Elute Plexa cartridge. The extract was concentrated and analyzed on a short Atlantis T3 column in 8.5 min. Metanephrines and their deuterated internal standards were monitored in positive electrospray ionization mode by multiple reaction monitoring.

RESULTS

Ion suppression was observed, but was compensated for by the respective internal standard. The analytical measurement range was 0.2-27.4 μmol/L and 0.3-14.6 μmol/L for metanephrine and normetanephrine, respectively. The intra-assay and total coefficient of variation throughout the linear ranges was 2.03%-2.11% and 2.20%-3.80% for metanephrine, and 4.50%-8.09% and 9.00%-10.00% for normetanephrine, respectively. Comparison with a commercial HPLC method using patient samples (n=65) by Passing-Bablok regression showed a slope of 1.000 and 1.014, y-intercept of -0.080 and -0.067, a correlation coefficient of 0.8830 and 0.9022, and a mean difference of 14.0% and -0.43% for metanephrine and normetanephrine, respectively.

CONCLUSIONS

This simple method for urine metanephrines is suitable for clinical use.

Dopamine excess in patients with head and neck paragangliomas

AIM

This study aimed to determine the prevalence of excess dopamine in relation to clinical symptoms and nuclear imaging in head and neck paraganglioma (PGL) patients.

PATIENTS AND METHODS

Thirty-six consecutive patients with head and neck PGLs, evaluated between 1993 and 2009, were included. Clinical symptoms, dopamine excess (urinary 3-methoxytyramine (3-MT) or dopamine and/or plasma dopamine or 3-MT) and (nor)epinephrine excess (urinary (nor)metanephrine) as well as (111)In-octreotide and (123)I-metaiodobenzylguanide (MIBG) scintigraphy were documented.

RESULTS

Dopamine excess was found in seven patients (19.4%), but was unrelated to clinical signs and symptoms. Excretion of other catecholamines was unremarkable, except in one patient with adrenal pheochromocytoma. (123)I-MIBG uptake (present in 36.1% of patients) was associated with dopamine excess (p = 0.03).

CONCLUSION

Dopamine excess is present in a considerable percentage of patients with head and neck PGL, and its measurement may be useful in follow-up. Measurement of other catecholamines is necessary to rule out co-existent pheochromocytoma.

Diagnostic accuracy of free and total metanephrines in plasma and fractionated metanephrines in urine of patients with pheochromocytoma

BACKGROUND

Plasma free and urinary metanephrines are recognized biomarkers for the assessment of pheochromocytoma. Plasma total metanephrines with a long half-life may represent another useful biomarker.

OBJECTIVE

The aim of this study is to evaluate the diagnostic performances of plasma total metanephrines alone or combined with free metanephrines and fractionated 24-h urinary metanephrines.

METHODS

A retrospective, case-control diagnostic test study was conducted between 1999 and 2007 in two university hospitals in Switzerland and two institutions in France. The patients included 46 cases with histologically proven pheochromocytoma, and 181 controls suspected of tumor with negative investigations and 3-year follow-up. None had renal dysfunction. Sensitivity and specificity were compared after expressing each measurement result as a ratio over its upper reference limit, adding the ratios of normetanephrine and metanephrine, and defining cut-off values of 1 or 2 for this sum.

RESULTS

Applying a cut-off value of 1, plasma free and total metanephrines and urinary fractionated metanephrines had similar sensitivities of 96% (95% confidence interval, 86-99%), 95% (85-99%), and 95% (84-99%) along with similar specificities of 89% (83-94%), 91% (84-95%), and 86% (80-91%). A cut-off of 2 for the sum of ratios over reference limit improves the specificity, and it can be used for a confirmation test based on another biomarker taken among the three biomarkers.

CONCLUSION

All three metanephrine-based tests perform equivalently for diagnosing pheochromocytoma in the absence of renal insufficiency, and can be conveniently associated two by two for confirming/excluding tumor.

Adrenal incidentaloma, clinical, metabolic, follow-up aspects: single centre experience

To investigate clinical characteristics, metabolic parameters and follow-up findings of subjects with incidentally discovered adrenal tumors. 376 consecutive subjects who have been evaluated since 2002 were included. Initial radiological examination was CT. Hormonal evaluation included 8.00 a.m. cortisol, DHEA-S, ACTH and in hypertensive subjects, plasma renin activity, and serum aldosterone. Urinary free cortisol (UFC), urinary normetanephrine, and metanephrine were measured. Overnight 1 mg dexamethasone suppression test was performed. Radiological evaluation was performed at 6th and 12th months and annually in subsequent visits. Hormonal evaluation was performed 6 months after the initial visit and annually in subsequent visits. Additionally, patients were evaluated for the development of Type 2 diabetes mellitus, hypertension, hyperlipidemia, and metabolic syndrome in 6-month intervals. Mean age of the participants was 54.7 ± 13.1. Female subjects were more commonly affected (70%). CT was the most frequent radiological intervention that discovered adrenal masses (57%). The vast majority of the participants (85.6%) had benign adrenal adenomas. Primary adrenocortical malignancy was detected in 4 subjects (1.1%). Subjects with adrenal adenomas had significantly smaller tumor diameters (P ≤ 0.001 vs. other tumors). Sensitivity and specificity of 40 mm as a cut-off value in the differentiation of adrenal gland malignancies from benign tumors was 73.3 and 54.8%, respectively. Most of the adrenal adenomas were non-functioning (73.5%). Subclinical Cushing syndrome (sCS) was detected in 12.5%. The overall prevalence of Type 2 diabetes mellitus, hypertension, hyperlipidemia, and metabolic syndrome was 18.4, 54.9, 59.6, and 48.1%, respectively. They were significantly more common in middle-aged and elderly subjects. During 24 months follow-up 10.2% of adenomas featured increase in tumor diameter and 2.06% developed sCS. Young subjects featured more stable tumor diameter and hormonal status. Most of the incidentally discovered adrenal tumors were non-functioning adrenal adenomas. Clinically overt hormone hypersecretion syndromes were mainly shown in young subjects, while adrenal gland malignancies and sCS were more common in older ages. Mass enlargement and development of subclinical cortisol secretion were not rare and observed especially in middle-aged and elderly subjects. Metabolic derangements were common; however, a possible independent association between adrenal adenoma and metabolic problems need to be elucidated with prospective studies.

Prospective evaluation of tumor size and hormonal status in adrenal incidentalomas

BACKGROUND

Because of the increased use of imaging interventions, more subjects have been diagnosed with adrenal incidentaloma in recent years.

AIM

To evaluate the risk of mass enlargement, hormone hypersecretion and development of adrenal carcinomas during short-term followup.

SUBJECTS AND METHODS

There were 317 subjects with incidentally discovered adrenal tumors in the registry. Forty subjects were excluded because of clinically overt hormone secretion at diagnosis and subjects with complete data were included in radiological (no.=150) and hormonal (no.=150) follow- up. Radiological evaluation was performed with computed tomography (CT) and/or magnetic resonance imaging (MRI). There were 143 subjects with adrenal adenomas and 7 subjects with other tumor types (cyst or myelolipoma). Median follow-up duration was 24 months.

RESULTS

Increase in tumor size was detected in 25 subjects (17.4%) with adenomas and 1 subject with adrenal myelolipoma (14.3%). Decrease in tumor size was found in 7 subjects (4.8%) with adrenal adenomas. One patient was diagnosed with adrenocortical carcinoma during follow-up. In subjects with non-functioning adrenal adenoma (NFA, no.=120) or subclinical Cushing syndrome (sCS) (no.=30), no subject developed clinically overt hormone hypersecretion, while 8 (6%) subjects in the NFA group developed sCS. Tumor diameter and follow-up duration were significantly higher in subjects who developed sCS.

CONCLUSION

In conclusion, we demonstrated that, despite being infrequent, adrenal tumors may increase in size, develop overt or subclinical hormone secretion or feature malignant transformation. Therefore, radiological and hormonal follow-up should be recommended to the patients. More investigations are needed for the establishment of long-term follow-up protocols.

A large deletion in the succinate dehydrogenase B gene (SDHB) in a Japanese patient with abdominal paraganglioma and concomitant metastasis

Recently, mutations in nuclear genes encoding two mitochondrial complex II subunit proteins, Succinate dehydrogenase D (SDHD) and SDHB, have been found to be associated with the development of familial pheochromocytomas and paragangliomas (hereditary pheochromocytoma/paraganglioma syndrome: HPPS). Growing evidence suggests that the mutation of SDHB is highly associated with abdominal paraganglioma and the following distant metastasis (malignant paraganglioma). In the present study, we used multiplex ligation dependent probe amplification (MLPA) analysis to identify a large heterozygous SDHB gene deletion encompassing sequences corresponding to the promoter region, in addition to exon 1 and exon 2 malignant paraganglioma patient in whom previously characterized SDHB mutations were undetectable. This is the first Japanese case report of malignant paraganglioma, with a large SDHB deletions. Our present findings strongly support the notion that large deletions in the SDHB gene should be considered in patients lacking characterized SDHB mutations.

[Diagnostic difficulties in recognizing of pheochromocytoma]

Pheochromocytoma (PH) is a tumour of chromaffin cells of the sympathetic nervous system and its clinical symptoms are associated with excessive production and release of catecholamines. The main criterion for clinical diagnosis of PH is finding increased concentrations of catecholamines or their metabolites in serum and/or urine. The largest diagnostic and therapeutic problems are patients with slightly elevated levels of methoxycatecholamines in serum and/ or urine. Aim of this study was to determine the cut-off point for elevated methoxycatecholamine in the collection of daily urine, which would give the basis for determining the reasonable recommendations of the biochemical criteria for diagnosis of PH. Retrospectively we analysed the results of 45 patients sent to laparoscopic adrenalectomy to the Department of General Surgery II with the preoperative diagnosis of pheochromocytoma. The diagnosis of pheochromocytoma was based on the finding of elevated 24-hour urine methoxycatecholamines. Based on the results of the histopathological examination patients were divided into two groups. Group 1 included 27 patients (14 women and 13 men) with histopathologically confirmed pheochromocytoma of adrenal gland. Group 2 consisted of 18 patients (11 women and 7 men), in which histopathological examination did not confirm the presence of pheochromocytoma. Mean age of patients in group 1: 46.8 +/- 14.4 years, in group 2: 55.7 +/- 13.7 years. Hypertension was diagnosed in 77.8% of those with group 1 and 94.4% from group 2. Based on the analyzed results of the CT, we found that the average tumor size in group 1 (4.2 +/- 1.9 cm) was statistically higher than in group 2 (2.9 +/- 1.1 cm). The average concentration of normetanephrine (NMN) in 24-hour urine in group 1 was statistically significantly higher than in group 2 (2,686 +/- 870.4 vs. 2375.1 +/- 754 mg/24h), as well as the average concentration of metanephrine (MN) (2533.4 +/- 3269.3 +/- 491.6 vs. 371.5 mg/24 hrs), and the sum of both methoxycatecholamines (NMN + MN) (5219.3 +/- 5190.6 vs. 1241.8 +/- 1202.2). The highest sensitivity in diagnosing pheochromocytoma with the rate of 81.5% was obtained for the sum of normetanephrine and metanephrine in 24-hour urine, while the sensivity for levels of each methoxycatecholamine separately was similar (63%). The highest specificity in the exclusion of PH was shown for 24-hour urine metanephrine (94.4%). The highest positive predictive value was found for the level of metanephrine in 24-hour urine (94.4%). The diagnostic cutoff concentrations of NMN, MN and NMN + MN for the diagnosis of pheochromocytoma were set. For the 24-hour urine NMN- cut-off > 1500 ug/24 h, for MN > 700 ug/24h and for NMN + MN > 1350 ug/24h. Shown above cut-off levels of methoxycatecholamines urine concentration will allow to pose a more accurate preoperative diagnosis of PH.

High prevalence of obesity in patients with non-functioning adrenal incidentalomas

OBJECTIVE

The influence of obesity on cancer development has been proven for numerous tumours. In contrast, the association between obesity and non-secreting adrenal incidentaloma has never been proven. Therefore, the aim of this study was to investigate this relationship in a large sample of patients.

METHODS

143 patients with benign non-secreting adrenal incidentalomas treated in the Department of Endocrinology at the Poznan University of Medical Sciences between the years 2000-2007 were examined. To rule out subclinical hyperfunctioning lesions, serum dehydroepiandrosterone sulphate, cortisol (8 am, 6 pm, and after 1 mg dexamethasone suppression), sodium and potassium, along with concentrations of sodium, potassium, vanillylmandelic acid, metanephrine and normetanephrine in 24-hour urine collection were determined. Radiological evaluation included computed tomography and/or magnetic resonance imaging. Only non-secreting lesions and those of benign radiologic appearance were considered. The patients body mass index was compared to that of the general population of Poland and the Western Poland Region of Wielkopolska.

RESULTS

The average body mass index of our patients was 28.77 kg/m2 (SD=4.71), with a 40% prevalence of obesity in the study group. One-proportion z-test showed a statistically significantly higher prevalence of obesity as compared to the general population of Poland and Wielkopolska (40% vs 12.5%, p<0.005); the results were similar for the whole cohort, and for each gender separately.

CONCLUSIONS

This clinical research study demonstrates a strong association between obesity and incidentally discovered non-functioning adrenal tumours.

Dietary influences on plasma and urinary metanephrines: implications for diagnosis of catecholamine-producing tumors

CONTEXT

Measurements of the 3-O-methylated metabolites of catecholamines [metanephrines (MNs)] in plasma or urine are recommended for diagnosis of pheochromocytoma. It is unclear whether these tests are susceptible to dietary influences.

OBJECTIVE

The aim of the study was to determine the short-term influence of a catecholamine-rich diet on plasma and urinary fractionated MNs.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a crossover study in a specialist medical center involving 26 healthy adults.

INTERVENTIONS

Subjects consumed catecholamine-rich nuts and fruits at fixed times on one day (about 35 mumol dopamine and 1 mumol norepinephrine) and catecholamine-poor products on another day. Blood and urine samples were collected at timed intervals before, during, and after experimental and control interventions.

MAIN OUTCOME MEASURES

Isotope-dilution mass spectrometry-based measurements of plasma and urinary concentrations of free and deconjugated 3-methoxytyramine (3-MT), normetanephrine (NMN), and MN were made.

RESULTS

The catecholamine-rich diet had substantial effects (up to 3-fold increases) on plasma concentrations and urinary outputs of free and deconjugated 3-MT. Dietary catecholamines had negligible influences on free NMN in plasma and urine, but substantial effects (up to 2-fold increases) on deconjugated NMN in plasma and urine. Concentrations of free and deconjugated MN in plasma and urine remained unaffected.

CONCLUSIONS

Dietary restrictions should be considered to minimize false-positive results for urinary and plasma deconjugated MNs during diagnosis of pheochromocytoma. Similar considerations appear warranted for plasma and urinary free 3-MT, but not for free NMN or MN, indicating advantages of measurements of the free compared to deconjugated metabolites.

Myocardial infarction in a 30-year-old patient with pheochromocytoma and type 1 neurofibromatosis

Chromaffinoma of the adrenal medulla (pheochromocytoma--PHEO) is a rare cause of arterial hypertension which is diagnosed incidentally or run in a family as a component of disease syndromes of the genetic origin. PHEO is diagnosed in about 5-10% of patients with type 1 neurofibromatosis (NF1). In a patient group with diagnosed arterial hypertension and NF1, PHEO is diagnosed with a much higher frequency, i.e. 20-56%. Myocardial injury in a patient without coronary risk factors is very rare. Increased circulating levels of catecholamines in patients with chromaffinoma may cause damage to myocardium without any atherosclerotic lesions in the coronary arteries. A correct diagnosis of PHEO allows the right treatment to be administered. The present paper discusses the case of a patient with NF1 and periodic arterial hypertension in the course of unidentified chromaffinoma, which was complicated with myocardial infarction. The evaluation of the secondary arterial hypertension led to the detection of the adrenal tumor. Based on the clinical presentation and the tumor characteristics, on computed tomography, PHEO was suspected. The level of methoxycatecholamines in a 24-hour urine sample significantly exceeded the reference values. The patient underwent laparoscopic, right-sided adrenalectomy, and the histopathological examination definitely concurred with the diagnosis of PHEO. During the post-surgical period, the arterial hypertension normalized without the administration of hypotensive drugs. The patient is still cared for by the clinic. The diagnosis toward PHEO is recommended if the patient with NF1 shows arterial hypertension. Proper diagnosis and treatment protects the patient against life-threatening cardiovascular complications.

Enhanced norepinephrine output during long-term desipramine treatment: a possible role for the extraneuronal monoamine transporter (SLC22A3)

To study the delay (2-6 weeks) between initial administration of norepinephrine reuptake inhibitor antidepressants and onset of clinical antidepressant action, we examined the effects of desipramine treatment on urinary and plasma catecholamines and their metabolites during the initial 6 weeks of treatment in depressed patients. Catecholamines and metabolites in 24-h urine collections and 8:00 a.m. plasma samples were measured at baseline and after 1, 4, and 6 weeks of desipramine treatment. Desipramine treatment produced significant increases in urinary norepinephrine (NE) and normetanephrine (NMN) and plasma NE at Weeks 4 and 6, but not at Week 1. The ratio of urinary NE/NMN was increased at Weeks 4 and 6, suggesting a reduction in the metabolism of NE to NMN at extraneuronal sites by Weeks 4 and 6. The increases in urinary NE and NMN and plasma NE at Weeks 4 and 6 of desipramine treatment were associated with a reduction in the conversion of NE to NMN. This would be compatible with a blockade of the extraneuronal monoamine transporter (organic cation transporter 3; SLC22A3) by NMN. Inhibition of the extraneuronal monoamine transporter may be an important component in the clinical pharmacology of the norepinephrine reuptake inhibitor antidepressant drugs, such as desipramine.

Evaluation of a urinary metanephrines reagent kit: an automated approach

INTRODUCTION

We report the results of a laboratory evaluation of the BioRad Urinary Metanephrines Reagent Kit. The test was designed for the quantitative measurement of normetanephrine and metanephrine in urine by high performance liquid chromatography. The kit was evaluated in view of improving assay reliability and specificity as compared to the manual method based on cation exchange chromatography and spectrophotometry.

METHODS

Performance was evaluated for precision, linearity, accuracy, sensitivity and detection limit based on National Committee on Clinical Laboratory Standards (NCCLS) protocols. Analytical precision was evaluated using commercial controls and patient sample. Accuracy was evaluated by assessing recovery. Linearity was determined using aqueous standards.

RESULTS

The within-run coefficient of variation (CV) for metanephrine and normetanephrine were 1.9 percent and 2.4 percent (low control); 4.2 percent and 3.5 percent (high control); 3.8 percent and 3.3 percent (patient sample), respectively. The between-day precisions were 3.8 percent and 4.3 percent (low control); and 5.5 percent and 3.7 percent (high control) for metanephrine and normetanephrine, respectively. The linearity curve showed metanephrine and normetanephrine to be linear with concentrations, to at least 1,600 microgramme per litre and 2,000 microgramme per litre, respectively. Analytical recovery averaged 102 percent for metanephrine and 95 percent for normetanephrine. Levels as low as 23 microgramme per litre normetanephrine and 10 microgramme per litre metanephrine were measured with this method. The detection limit was 3.3 microgramme per litre for metanephrine.

CONCLUSION

The performance characteristics of automated sample preparation and auto-injection facilitate handling of larger number of samples as well as improve assay reliability.

Liquid chromatography method for detecting native fluorescent bioamines in urine using post-column derivatization and intramolecular FRET detection

Liquid chromatography (LC) with fluorescence detection is described for simultaneous determination of native fluorescent bioamines (indoleamines and catecholamines). This is based on intramolecular fluorescence resonance energy transfer (FRET) in an LC system following post-column derivatization of native fluorescent bioamines' amino groups with o-phthalaldehyde (OPA). OPA fluorescence was achieved through an intramolecular FRET process when the molecules were excited at maximum excitation wavelength of the native fluorescent bioamines. Bioamines separated by reversed-phase LC on ODS column were derivatized with OPA and 2-mercaptoethanol. This method provides sufficient selectivity and sensitivity for the determination of normetanephrine, dopamine, tyrosine, 5-hydroxytryptamine, tryptamine, and tryptophan in healthy human urine without prior sample purification.

[Difficult diagnosis of a pancreatic paraganglioma]

INTRODUCTION

The paraganglioma is a rare tumour that can sometimes develop near to the pancreatic gland and can occasionally mimic an intra pancreatic mass. Invasive investigations with puncture or primary surgical resection must be avoided because of the risk of vital complications.

EXEGESIS

We report on the case of a 41 years old woman presenting with a mass apparently affecting the pancreatic gland. She also presented with malaises. Paraganglioma was suspected because of the malaises and the blood pressure crises. The diagnosis was permitted by the findings of high urinary metanephrine levels. So the tumour was resected without previous fine needle aspiration and with specific anaesthetic measures. No complication was observed.

CONCLUSION

When a patient presents with a pancreatic mass, physician must carefully take into account the possibility of a paraganglioma particularly when malaises are present.

The diagnostic efficacy of urinary fractionated metanephrines measured by tandem mass spectrometry in detection of pheochromocytoma

BACKGROUND

There are limitations to currently available biochemical tests for pheochromocytoma. Our objective was to evaluate the diagnostic efficacy of a novel tandem mass spectrometry assay for the measurement of fractionated urinary metanephrines in patients suspected to have a pheochromocytoma. We also developed clinically based cut-offs for positivity of this measurement.

METHODS

We examined the medical records of 506 patients (including 102 patients with a catecholamine-producing tumour) who underwent measurement of 24-h urinary fractionated metanephrines using tandem mass spectrometry as well as adrenal imaging at Mayo Clinic, Rochester. The cut-offs for positivity were defined as follows: total metanephrines (sum of the metanephrine fractions) 5163 nmol/day, normetanephrine fraction 4001 nmol/day, metanephrine fraction 1531 nmol/day. Receiver operating characteristic (ROC) curves were constructed.

RESULTS

The diagnostic efficacy was as follows: normetanephrine fraction sensitivity 87.3% [(95% confidence interval (CI) 79.4-92.4%], specificity 95.0% (92.5-96.8); metanephrine fraction sensitivity 56.9% (47.2-66.1), specificity 95.0% (92.5-96.8); elevation of either normetanephrine or metanephrine fraction sensitivity 97.1% (91.7-99.0) and specificity 91.1% (87.9-93.5). Areas under the ROC curves (AUCs) were 0.972 (95% CI 0.955-0.990) for the normetanephrine fraction, 0.800 (0.741-0.858) for the metanephrine fraction, 0.991 (0.985-0.996) for total metanephrines, and 0.991 (0.985-0.996) for a regression-derived ROC curve incorporating both the metanephrine and normetanephrine fractions.

CONCLUSION

Measurement of 24-h urinary fractionated metanephrines by a tandem mass spectrometry assay appears to be an effective biochemical technique in the investigation of pheochromocytoma.