Pheochromocytoma: yes or no?
A 76-year-old woman was admitted for cardiac decompensation, hypertension, and renal failure. To explore her chronic hypertension, urinary fractionated metanephrines were quantified. Fig. 1A shows the chromatogram of the patient's urine, and Fig. 1B shows the chromatogram of a calibration standard. A very large methoxytyramine peak was observed (Fig. 1A, black arrow). The peak signal was saturated, representing a concentration greater than 16 200 nmol/L (0-1 600 nmol/L).
[FIGURE 1 OMITTED]
1. What is the methoxytyramine?
2. Are isolated increases in methoxytyramine frequently observed?
3. What causes should be considered?
Methoxytyramine is a dopamine metabolite. Isolated methoxytyramine increases are rare. Theyare observed in (a) drug interferences with tricyclic antidepressant or antihypertensive treatments (1, 2), (b) food intake (e.g., walnuts, pineapple) (2, 3), and (c) exceptional dopamine-secreting neoplasms (4, 5). Clinical context and therapeutic information are crucial and must be systematically evaluated. In this case, the clinician overlooked a treatment by dopamine the day before sampling, which caused this increased methoxytyramine concentration.
Author Contributions: All authors confirmed they have contributed to the intellectual content of this paper and have met the following 3 requirements: (a) significant contributions to the conception and design, acquisition of data, or analysis and interpretation of data; (b) drafting or revising the article for intellectual content; and (c) final approval of the published article.
Authors' Disclosures or Potential Conflicts of Interest: No authors declared any potential conflicts of interest.
(1.) Estey MP, Diamandis EP, Eisenhofer G, Pacak K, Maher ER, Young WF, De Krijger RR. Pheochromocytoma. Clin Chem 2013;59:466-72.
(2.) Eisenhofer G, Goldstein DS, Walther MM, Friberg P, Lenders JW, Keiser HR, Pacak K. Biochemical diagnosis of pheochormocytoma: how to distinguish true- from false-positive test results. J Clin Endocrinol Metab 2003;88:2656-66.
(3.) De Jong W, Eisenhofer G, Post WJ, Muskiet FAJ, De Vries EGE, Kema IP. Dietary influences on plasma and urinary metanephrines: implications for diagnosis of catecholamine-producing tumors. J Clin Endocrinol Metab 2009; 94:2841-9.
(4.) Peaston RT, Graham KS, Chambers E, Van der Molen JC, Ball S. Performance of plasma free metanephrines measured by liquid chromatography-tandem mass spectrometry in the diagnosis of pheochromocytoma. Clin Chimica Acta 2010;411:546-52.
(5.) Proye C, Fossati P, Fontaine P, Lefebvre J, Decoulx M, Wemeau JL, et al. Dopamine-secreting pheochromocytoma: an unrecognized entity? Classification of pheochromocytomas according to their type of secretion. Surgery 1986;100:1154-62.
Carine Garcia Hejl, * Emmanuel Dedome, Denis Chianea, Jose Ramirez Martinez, and Philippe Vest
Laboratory of Biochemistry, Percy Hospital, Clamart, France.
* Address correspondence to this author at: Percy Hospital, Biochemistry, 101 Ave. Henri Barbusse, Clamart, France 92140. Fax 141466458; e-mail firstname.lastname@example.org.
Received May 13, 2013; accepted May 28, 2013.
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|Title Annotation:||the Clinical Chemist: What Is Your Guess?|
|Author:||Hejl, Carine Garcia; Dedome, Emmanuel; Chianea, Denis; Martinez, Jose Ramirez; Vest, Philippe|
|Date:||Mar 1, 2014|
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