Determination of catecholamines and metanephrines in urine by capillary electrophoresis-electrospray ionization-time-of-flight mass spectrometry

A method successfully coupling capillary electrophoretic separation to time-of-flight mass spectrometric (TOFMS) detection for the simultaneous analysis of catecholamines (dopamine, norepinephrine, and epinephrine) and their O-methoxylated metabolites (3-methoxytyramine, normetanephrine, and metanephrine) is described. The inner capillary wall was coated with polyvinyl alcohol in order to obtain baseline resolution of catecholamines and metanephrines and to ensure reproducibility without extensive restorative washing of the capillary. Using electrokinetic injection, detection limits of 0.3 microM for dopamine and norepinephrine, 0.2 microM for 3-methoxytyramine and normetanephrine, and 0.1 microM for epinephrine and metanephrine were achieved with standard solutions. The usefulness of this approach was demonstrated by applying the developed method to the analysis of a spot collection of human urine from a healthy volunteer. The catecholamines and metanephrines were removed from the urine samples and preconcentrated by simultaneous SPE on cation-exchange sorbents. The recoveries of all analytes, with the exception of epinephrine (75%), were over 80%. Catecholamines and metanephrines in the urine samples were quantitated using 3,4-dihydroxybenzylamine as an internal standard. Submicromolar concentrations, consistent with the catecholamine and metanephrine levels reported for normal human urine, were detected.     

Ordering Pattern and Performance of Biochemical Tests for Diagnosing Pheochromocytoma Between 2000 and 2008

ObjectiveTo examine what tests are ordered by physicians for pheochromocytoma diagnosis and how those tests perform in modern clinical practice.MethodsIn this case series, electronic medical records of patients seen between January 2000 and July 2008 at a large academic hospital in Los Angeles, California, were queried, and patients older than 15 years who underwent any 1 of 5 tests for pheochromocytoma (measurement of plasma catecholamines, plasma fractionated metanephrines, urinary catecholamines, urinary metanephrines, or urinary vanillylmandelic acid) were identified. Because testing was performed in various reference laboratories, test results were classified into 1 of 3 categories: (a) markedly elevated, (b) moderately elevated, or (c) normal. Patient demographics, clinical history, test results, imaging study findings, and pathology records were reviewed.ResultsA total of 3980 tests were ordered for 1898 patients. Pretest probability was 2.2% (based on 681 patients in whom pheochromocytoma was confirmed or excluded), and hypertension was the most common indication for testing. The number of patients tested and the number of tests ordered increased over the years. The ordering pattern stabilized since 2006 when urinary metanephrines, urinary catecholamines, and plasma metanephrines were ordered more frequently. Sensitivity was highest for urinary metanephrines and vanillylmandelic acid, specificity was highest for vanillylmandelic acid and urinary catecholamines, and positive likelihood ratio was highest for vanillylmandelic acid. Positive predictive value for markedly elevated test results was 39% to 83%, while that for moderately elevated test results was only 2% to 14%.ConclusionsOrdering pattern and test performance differ significantly from those recommended and reported by large centers. The best testing strategy should incorporate local experience. Categorizing test results as markedly elevated, moderately elevated, and normal is important for result interpretation. (Endocr Pract. 2009;15:313-321)     

Biochemical tests for diagnosis of phaeochromocytoma: urinary versus plasma determinations.

Fifteen patients with hypertension due to phaeochromocytoma and 35 controls with essential hypertension were studied to assess the diagnostic value of urinary and plasma biochemical determinations in phaeochromocytoma. In every case of phaeochromocytoma the urinary concentration of vanillylmandelate, metanephrines, or adrenaline plus noradrenaline was diagnostic of the disease irrespective of whether the patient was normotensive or hypertensive at the time. Plasma determinations of adrenaline and noradrenaline, however, gave falsely negative results on three occasions. These findings suggest that urinary biochemical determinations--particularly of metanephrines--are more reliable than plasma catecholamine measurements as a test for phaeochromocytoma. The test is particularly useful in patients with intermittent hypertension.     

Quantitation of 3,4-dihydroxyphenylacetaldehyde and 3, 4-dihydroxyphenylglycolaldehyde, the monoamine oxidase metabolites of dopamine and noradrenaline, in human tissues by microcolumn high-performance liquid chromatography.

We recently described the chemical synthesis of 3, 4-dihydroxyphenylacetaldehyde and 3,4-dihydroxyphenylglycolaldehyde, the monamine oxidase metabolites of dopamine and noradrenaline, respectively. We demonstrated the neurotoxicity of these compounds. Catecholamine nerve cells which synthesize these aldehydes die in degenerative brain diseases, such as Parkinson's and Alzheimer's. Here we describe a sensitive method for separating these catecholaldehydes from catecholamines and their other oxidative and methylated metabolites by microcolumn high-performance liquid chromatography with electrochemical detection. We then quantitate catecholamines and their major metabolites in human brain, plasma, and urine. The method can be used to determine the role of these catecholaldehydes in human disease.     

Prazosin in the preoperative management of patients with phaeochromocytoma

The use of prazosin--a drug selectively blocking alpha-adrenergic receptors--was considered for the preoperative management of patients with phaeochromocytoma. Prazosin was administered to 8 patients in whom the diagnosis was established basing on the clinical symptoms and daily excretion of catecholamines and their metabolites with the urine. Preliminary diagnosis was subsequently confirmed operationally. Prazosin could be considered effective only in the part of treated patients. This was manifested by the drop in blood pressure to nearly normal values and diminished attacks. However, prazosin did not prevent blood pressure increase during anaesthesia and surgery. The use of prazosin in patients with phaeochromocytoma for preoperative management may be an alternative pharmacological therapy producing appropriate drop in blood pressure in some patients.     

Current progress and future challenges in the biochemical diagnosis and treatment of pheochromocytomas and paragangliomas.

Findings from five independent studies - with close to 350 patients with pheochromocytoma and more than 2,500 in whom the tumor was excluded - indicate that measurements of plasma free metanephrines provide an overall diagnostic sensitivity of 98% and specificity of 92%. The recommendation that initial testing for the tumor should always include measurements of either plasma or urinary fractionated metanephrines results from recognition of the high diagnostic sensitivity of measurements of plasma metanephrines. The few patients with pheochromocytoma in whom the test may not yield a positive result include those with very small tumors or microscopic disease and others with tumors that do not produce norepinephrine and epinephrine. Such patients are typically normotensive and do not exhibit symptoms of catecholamine excess. Additional measurements of methoxytyramine can be useful for detecting those tumors that produce only dopamine. Suboptimal diagnostic specificity and difficulties in distinguishing true- from false-positive elevations of plasma metanephrines remain challenges for diagnosis. Improvements in analytical technology (e.g., liquid chromatography with tandem mass spectrometry) and new strategies for follow-up testing provide possible solutions to these problems. The single most important remaining clinical care challenge is the development of effective cures for patients with malignant disease. Current treatments, none of which are truly satisfactory, include chemotherapy and radiopharmaceutical therapy with (131)I-labelled M-iodobenzylguanidine or radioactive somatostatin analogues. Improvements in treatment may in the future come from several fronts, but proof of efficacy ideally will require well-coordinated multicenter prospective trials in larger numbers of patients than in previous studies.     

Pheochromocytoma And Pregnancy:A Rare But Dangerous Combination

ObjectiveTo review the literature on pheochromocytoma in pregnancy (PIP) published during the 11-year period 1998 through 2008.MethodsWe searched MEDLINE data sources from 1998 through 2008 using the search terms “pheochromocytoma” and “pregnancy” and reviewed case reports of PIP published in English.ResultsWe identified 54 case reports in MEDLINE data sources, of which 51 reports including 60 cases were reviewed. In comparison with the previous decade, a decreased rate of antenatal diagnosis (from 83% to 70%) and increased maternal and fetal mortality (from 4% to 12% and from 10% to 17%, respectively) were observed. Prematurity was present in 53% of the infants of mothers with antenatally diagnosed pheochromocytoma who gave birth to a live infant. Hypertension was the most common manifestation (88%), with 33% of patients having antepartum hypertensive crises. Urinary catecholamines (64%) and metanephrines (40%) were the most commonly used tests, whereas urinary and plasma metanephrines were the most sensitive tests (100%). Ultrasonography had poor sensitivity (54%), especially during the third trimester. Magnetic resonance imaging was 100% sensitive for adrenal tumors but had only 50% sensitivity for extra-adrenal tumors. A syndromic or familial presentation was seen in 18% of patients, and 32% of patients had bilateral or extraadrenal tumors.ConclusionIn comparison with the previous decade, a decreased rate of antenatal diagnosis and increased maternal and fetal mortality were observed. Prematurity was a major morbidity associated with PIP. Hypertensive crises were more common during pregnancy. Urinary and plasma metanephrines had the highest sensitivity to detect PIP. Genetic screening should be offered to all pregnant women with pheochromocytoma. (Endocr Pract. 2010;16:300-309)     

Extraction and separation of urinary catecholamines as their diphenyl boronate complexes using C18 solid-phase extraction sorbent and high-performance liquid chromatography

The clinical utility of a one-step extraction procedure based on the retention of a diphenyl boronate-catecholamine complex on a C18 solid-phase extraction sorbent was investigated for the measurement of urinary catecholamines. Although recoveries with the extraction procedure were optimal over a relatively broad pH range (7.5-9.5), analytical factors such as sample loading and elution flow-rates, wash step and elution conditions, the concentration of catecholamines in urine to be extracted and the type of C18 sorbent used for extraction were found to influence the efficiency of this procedure and would therefore need to be controlled for optimal recoveries. Under optimal conditions the recovery of noradrenaline, adrenaline and dopamine from spiked urine was high and reproducible (mean recoveries were >85% for all catecholamines). The effectiveness of sample clean-up step was demonstrated by reverse phase, ion pair high-performance liquid chromatography with electrochemical detection. The method described was found to be suitable for the routine measurement of catecholamines in urine in clinical biochemistry laboratories. It has a high sample extraction throughput (40/h) and has adequate precision (between batch CV<8%) and sensitivity (LOD<30 nmol/l; LOQ<65 nmol/l) for all the catecholamines measured. The method has acceptable accuracy, showing a mean bias of 6.6% for noradrenaline, 7.3% for adrenaline and 6.8% for dopamine from the mean value of laboratories (N=69) participating in an External Quality Assurance scheme for greater than 12 months.     

Diagnostic difficulties in adrenal incidentaloma--analysis of 125 cases

INTRODUCTION: Therapeutic approach to incidentaloma, in spite of existing algorithms, is not always obvious due to diagnostic difficulties. The aim of the study was to assess the validity of the initial diagnoses of incidentaloma which determined the qualification for the operation. MATERIAL AND METHODS: 125 patients hospitalised in the Endocrinology Dept. of the Medical University of Bialystok in the years 2003-2005 and in the Endocrinology dept. of Voivodeship Hospital of Bialystok. The patients were clinically and hormonally examined (metanephrines in daily urine collection, daily cortisol rhythm, short dexamethasone test, aldosterone, and renin plasma activity, Na, K levels in the serum) as well as computer tomography of the adrenal glands were performed. RESULTS: 42 patients were qualified for adrenalectomy. Adenoma was confirmed in 25 patients (in 7 subclinical Cushing syndrome was diagnosed, in 2 Conn disease, in 16 inactive changes), phaeochromocytoma in 6 patients, cysts in 3, lipoma in 2, carcinoma in one, in 4 patients metastases (in 2 of kidney carcinoma, in 1 of malignant melanoma and in 1 of planocellular carcinoma) and in one oncocytoma. Metanephrines urine measurements showed 33% of false positive results. CONCLUSIONS: Qualification for adrenalectomy requires an assessment of tumor's enlargement, its tissue density, morphology and growth dynamics. To reduce the percentage of false positive results of metanephrine measurement there is to eliminate an influence of some drugs, victuals, beverages and nicotine and eventually to carry out additional tests. The decision as to proceeding with adrenal incidentaloma should be individualized based on clinical symptoms, hormonal tests and tumor morphology.     

Effects of Handling or Immobilization on Plasma Levels of 3,4-Dihydroxyphenylalanine, Catecholamines, and Metabolites in Rats

In conscious animals, handling and immobilization increase plasma levels of the catecholamines norepinephrine (NE) and epinephrine (EPI). This study examined plasma concentrations of endogenous compounds related to catecholamine synthesis and metabolism during and after exposure to these stressors in conscious rats. Plasma levels of 3,4-dihydroxyphenylalanine (DOPA), NE, EPI, and dopamine (DA), the deaminated catechol metabolites 3,4-dihydroxyphenylglycol (DHPG), and 3,4-dihydroxyphenylacetic acid (DOPAC), and their O-methylated derivatives methoxyhydroxyphenylglycol (MHPG) and homovanillic acid (HVA) were measured using liquid chromatography with electrochemical detection at 1, 3, 5, 20, 60, and 120 min of immobilization. By 1 min of immobilization, plasma NE and EPI levels had already reached peak values, and plasma levels of DOPA, DHPG, DOPAC, and MHPG were increased significantly from baseline, whereas plasma DA and HVA levels were unchanged. During the remainder of the immobilization period, the increased levels of DOPA, NE, and EPI were maintained, whereas levels of the metabolites progressively increased. In animals immobilized briefly (5 min), elevated concentrations of the metabolites persisted after release from the restraint, whereas DOPA and catecholamine levels returned to baseline. Gentle handling for 1 min also significantly increased plasma levels of DOPA, NE, EPI, and the NE metabolites DHPG and MHPG, without increasing levels of DA or HVA. The results show that in conscious rats, immobilization or even gentle handling rapidly increases plasma levels of catecholamines, the catecholamine precursor DOPA, and metabolites of NE and DA, indicating rapid increases in the synthesis, release, reuptake, and metabolism of catecholamines.     

Liquid chromatographic/mass spectrometric procedure for measurement of NAD catabolites in human and rat plasma and urine

Monitoring level of the metabolites of the coenzyme NAD such as nicotinamide and its oxidized and methylated derivatives is important due to therapeutic applications of these compounds and monitoring of oxidative stress. We evaluated feasibility of using HPLC with electrospray ion-trap mass detection for single run separation and quantitation of all the NAD metabolites. We achieved good separation and retention of all the metabolites of interest using reversed-phase with ion-pairing. Single ion monitoring or tandem MS were used for detection and quantitation of the specific compounds with good linearity. The method was able to detect all the physiological metabolites in plasma samples of rats and humans or in urine. However, full validation is necessary before this method could be routinely applied.     

Liquid Chromatographic/Mass Spectrometric Procedure for Measurement of NAD Catabolites in Human and Rat Plasma and Urine

Monitoring level of the metabolites of the coenzyme NAD such as nicotinamide and its oxidized and methylated derivatives is important due to therapeutic applications of these compounds and monitoring of oxidative stress. We evaluated feasibility of using HPLC with electrospray ion-trap mass detection for single run separation and quantitation of all the NAD metabolites. We achieved good separation and retention of all the metabolites of interest using reversed-phase with ion-pairing. Single ion monitoring or tandem MS were used for detection and quantitation of the specific compounds with good linearity. The method was able to detect all the physiological metabolites in plasma samples of rats and humans or in urine. However, full validation is necessary before this method could be routinely applied.     

Determination of urinary steroid sulfate metabolites using ion paired extraction

The need for laboratories accredited by the World Anti-Doping Agency (WADA) to develop methods of analysis for steroids excreted primarily as their sulfate conjugates has faced significant analytical challenges. One of the issues relates to the extraction of these metabolites from urine in a relatively pure state. The use of (-)-N,N-dimethylephedrinium bromide as an ion pairing reagent was optimised to produce a method that is selective for the extraction of steroid sulfates prior to GC-MS or LC-MS analysis, with minimal contributions from the urine matrix. The recovery of androsterone from its sulfate conjugate was determined to be 67% with a relative quantitative uncertainty of +/-14% (k = 2).     

Determination of vanilmandelic acid in urine by coupled-column liquid chromatography combining affinity to boronate and separation by anion exchange

An automated liquid chromatographic method for assaying vanilmandelic acid in urine is described. Vanilmandelic acid and potential interfering substances, such as catechol compounds and their metabolites, have been tested for affinity to boronic acid-substituted silica at various pH values. Vanilmandelic acid and the internal standard, isovanilmandelic acid, were bound to the boronate matrix at an acidic pH, whereas for instance catecholamines were unretained and passed through the column. The α-hydroxycarboxylic acids were then desorbed by another mobile phase (pH 6.0) and transferred to an anion exchanger for chromatography and electrochemical detection. A relative standard deviation of 2.8% was obtained for the analysis of human urine samples containing 6.6 μM vanilmandelic acid.     

Metabolism and pharmacokinetic studies of propionylpromazine in horses

The propionylpromazine concentrations in plasma after intramuscular administration to horses were determined using gas chromatography with nitrogen-phosphorus detection. After hydrolysis by β-glucuronidase/arylsulphatase, the parent drug and three metabolites were detected in urine. The metabolites were identified as 2-(1-hydroxypropyl)promazine, 2-(1-propenyl)promazine and 7-hydroxypropionylpromazine by gas chromatography-mass spectrometry. No N-demethylated or sulphoxidated metabolites of propionylpromazine were observed in the horse urine.     

Development and Challenge of HIV/AIDS Testing Laboratory Network and Quality Assurance System in China

This paper describes the development and challenge of HIV/AIDS testing laboratory network and quality assurance system in China. At present,the HIV/AIDS testing laboratories includes three classes,the National AIDS Reference Laboratory,HIV/AIDS confirmatory laboratories and HIV/AIDS screening laboratories. All of them are accredited by the health authorities,and each class of laboratories take charge of their function strictly according to the "National Management of HIV/AIDS Detection (2006)". A complete quality assurance and quality control system for HIV/AIDS testing has been developed,which includes technical training,strict laboratory monitoring and approval,examination or proficiency testing on HIV/AIDS detection,and quality evaluation and supervision of HIV/AIDS diagnostic kits. Besides conduct the routine anti-HIV antibody test,more and more laboratories began to conduct other tests,such as CD4 T lymphocyte cell counting,HIV viral load,HIV DNA PCR,genotyping,drug resistance,and HIV-1 recent infection test. The primary challenges faced by the HIV/AIDS testing laboratory network are in the areas of laboratory management and quality control. For example,the provincial PT program is inefficient,the internal quality control is conducted perfunctorily,personnel training can not met the needs of the workplace,which need to be improved.     

Localization of pheochromocytoma by selective venous catheterization and assay of plasma catecholamines.

The diagnosis of pheochromocytoma rests primarily on determination of the 24-hour urinary excretion of catecholamines and their metabolites. In most cases nephrotomography and selective arteriography or venography, or both, are sufficient to localize the tumour. Selective venous catheterization and the assay of plasma catecholamines should be considered for pheochromocytoma localization in: (a) patients in whom standard techniques fail to localize the tumour; (b) patients who exhibit idiosyncratic reactions to the angiographic contrast materials; (c) young patients or patients with familial pheochromocytoma, including those with multiple neurofibromatosis or multiple endocrine adenomatosis, type 2; (d) patients with recurrent, malignant, or suspected multicentric or extra-adrenal tumours; and (e) patients excreting only norepinephrine in the urine. The validity of the results is particularly dependent on the skill with which venous catheterization is carried out.     

A simple method for concentration of biogenic amines and their metabolites from biological samples for analysis by HPLC-EC

This report describes a new rapid, convenient and inexpensive method of concentrating biogenic amines and their metabolites from biological samples for analysis by HPLC-EC. Recovery of standard monoamines and metabolites from artificial cerebrospinal fluid (CSF) solution following lyophilization in the presence of glutathione (1.2 mg/ml, final concentration) and EGTA (1.8 mg/ml, final concentration) was greater than 89%; the coefficient of variation was 0.6-3.7%, depending on the specific amine or metabolite concentrated. Lyophilization as a one step procedure is suitable for concentrating biogenic amines and metabolites from biological fluids such as CSF that contain low concentrations of protein and other interfering substances. When concentrating compounds from plasma, which contains large quantities of protein and other electrochemically active materials, it is necessary to add an extraction step, such as alumina extraction. By substituting 0.05 M HCl for the conventional eluent, 0.1 M HClO4, we were able to increase recoveries of catecholamines from plasma by approximately 20%. Recovery of endogenous catecholamines from plasma following the combined alumina extraction - lyophilization procedure was 81 +/- 1%.     

Evaluation of the usefulness of certain localization methods in diagnosis of pheochromocytoma]

Localization tests including TC-scans, scintigraphy with 131I-radiolabelled metaiodobenzylguanidine and ultrasound have been performed in 68 patients with diagnosed pheochromocytoma. Diagnosis was based on clinical symptoms and increased catecholamines and/or their metabolites excretion with the urine. Proper diagnosis with CT-scans was 97%, scintigraphy--92%, and ultrasound--93%; false negative results in scintigraphy amounted to 8% (3 patients) and 5% (3 patients) in case of ultrasound. CT-scans were free of such errors. False positive diagnosis was made in 2 (3%) patients with CT-scans and in 1 (2%) patient tested with ultrasound. These results suggest that pheochromocytoma may be precisely localized with non-invasive techniques, especially CT-scans.     

Serum chromogranin-alpha immunoradiometric assay in the diagnosis of pheochromocytoma

BACKGROUND: The diagnosis of pheochromocytoma is based on laboratory tests that demonstrate an increase in urinary excretion of catecholamines or their metabolites. Chromogranin A (CgA) is a member of the granin family and is widely distributed in neuroendocrine cells and particularly in chromaffin adrenal cells. Consequently, serum CgA increases in patients affected by pheochromocytoma and other diseases of the chromaffin system. AIM: This study investigated the performance of serum CgA assay in the diagnosis of pheochromocytoma and compared serum CgA with 24-hour urinary epinephrine (E), norepinephrine (NE), vanillylmandelic acid (VMA) and metanephrines (MNs). METHODS: We enrolled 15 patients with histologically proven pheochromocytoma; 100 healthy blood donors and 148 patients with essential hypertension were enrolled as controls. Serum CgA was assayed by a specific immunoradiometric method (IRMA). Urinary tests were done with high performance liquid chromatography (HPLC). RESULTS: Circulating CgA showed a higher sensitivity (1.00), specificity (0.96) and accuracy (0.96) than all other tests. Serum levels of CgA clearly increased from blood donors and patients with essential hypertension to patients with pheochromocytoma (p<0.0001). Furthermore, a strong relationship between serum CgA and tumor mass was found (p<0.0001). In conclusion, our data suggest that the CgA assay might be used as a single test for the diagnosis of pheochromocytoma.