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.

Measurements of plasma methoxytyramine, normetanephrine, and metanephrine as discriminators of different hereditary forms of pheochromocytoma

BACKGROUND

Pheochromocytomas are rare catecholamine-producing tumors derived in more than 30% of cases from mutations in 9 tumor-susceptibility genes identified to date, including von Hippel-Lindau tumor suppressor (VHL); succinate dehydrogenase complex, subunit B, iron sulfur (Ip) (SDHB); and succinate dehydrogenase complex, subunit D, integral membrane protein (SDHD). Testing of multiple genes is often undertaken at considerable expense before a mutation is detected. This study assessed whether measurements of plasma metanephrine, normetanephrine, and methoxytyramine, the O-methylated metabolites of catecholamines, might help to distinguish different hereditary forms of the tumor.

METHODS

Plasma concentrations of O-methylated metabolites were measured by liquid chromatography with electrochemical detection in 173 patients with pheochromocytoma, including 38 with multiple endocrine neoplasia type 2 (MEN 2), 10 with neurofibromatosis type 1 (NF1), 66 with von Hippel-Lindau (VHL) syndrome, and 59 with mutations of SDHB or SDHD.

RESULTS

In contrast to patients with VHL, SDHB, and SDHD mutations, all patients with MEN 2 and NF1 presented with tumors characterized by increased plasma concentrations of metanephrine (indicating epinephrine production). VHL patients usually showed solitary increases in normetanephrine (indicating norepinephrine production), whereas additional or solitary increases in methoxytyramine (indicating dopamine production) characterized 70% of patients with SDHB and SDHD mutations. Patients with NF1 and MEN 2 could be discriminated from those with VHL, SDHB, and SDHD gene mutations in 99% of cases by the combination of normetanephrine and metanephrine. Measurements of plasma methoxytyramine discriminated patients with SDHB and SDHD mutations from those with VHL mutations in an additional 78% of cases.

CONCLUSIONS

The distinct patterns of plasma catecholamine O-methylated metabolites in patients with hereditary pheochromocytoma provide an easily used tool to guide cost-effective genotyping of underlying disease-causing mutations.

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.