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A pain in the neck.

CASE DESCRIPTION

A 62-year-old man complaining of neck pain was found to have a mass in the left carotid region. He was on treatment for hypertension but had no symptoms suggestive of catecholamine excess. Urinary dopamine values were near or above the upper reference limit in 2 samples (Table 1). Free and total plasma methoxytyramine, plasma dopamine, and urine methoxytyramine concentrations were above their upper reference limits (46-, 9-, 54-, and 6-fold, respectively). The values for other catecholamines were normal.

QUESTIONS

1. What is the most likely diagnosis?

2. What are the clinical signs associated with the production of dopamine and methoxytyramine?

3. What is the best way to follow this disorder?

The answers are on the next page.

ANSWERS

This mass was a paraganglioma. Dopamine is metabolized by catechol-O-methyltransferase into methoxytyramine within head and neck paragangliomas (HNPGL). Urinary dopamine derives from renal extraction and decarboxylation of circulating L-dopa (1). Sixty-nine percent of HNPGL are benign, and 5%-16% secrete catecholamines. Isolated secretion of methoxytyramine is limited to 8%13% of HNPGL (2, 3). Unlike norepinephrine- and epinephrine-secreting tumors, dopamine-secreting tumors lack symptoms of catecholamine excess. Methoxytyramine is the best biochemical marker to monitor the relapse of dopamine-producing HNPGL.

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.

References

(1.) Wolfovitz E, Grossman E, Folio CJ, Keiser HR, Kopin IJ, Goldstein DS. Derivation of urinary dopamine from plasma dihydroxyphenylalanine in humans. Clin Sci 1993;84:549-57.

(2.) van Duinen N, Steenvoorden D, Kema IP, Jansen JC, Vriends AH, Bayley JP, et al. Increased urinary excretion of 3-methoxytyramine in patients with head and neck paragangliomas. J Clin Endocrinol Metab 2010;95:209-14.

(3.) Eisenhofer G, Goldstein DS, Sullivan P, Csako G, Brouwers FM, Lai EW, et al. Biochemical and clinical manifestations of dopamine-producing paragangliomas: utility of plasma methoxytyramine. J Clin Endocrinol Metab 2005;90:2068-75.

Jardena Puder, [1] [[dagger]] Raphael Stadelmann, [1] ([dagger]) Patrick Schoettker, [2] Thierry Buclin, [3] and Eric Grouzmann [4] *

[1] Departments of Endocrinology and [2] Anesthesiology, [3] Division of Clinical Pharmacology, and [4] Service of Biomedicine, University Hospital of Lausanne

(CHUV), Lausanne, Switzerland.

[[dagger]] These authors contributed equally to this work.

DOI: 10.1373/clinchem.2012.202077
Table 1. Measured catecholamine and metabolite concentrations during
monitoring of the disease.3

Date                              Urine, nmol/24 h

                 NMN (b)   MN      MT        NE     E      DA

May 2008           2121     735    10 880#   374     57    3222
July 2008          2079    1476    12 704#   248     48    3547#
September 2008     1836     693       617    306     31     998
May 2009           2799    1178     2636#    446     24    1377
July 2010          1793     916      1211    316     33    1799
February 2011      1936     834      1393    316     39    1288
URL               <3800    <1880    <1900    <610   <130   <3300

Date                                Plasma, nmol/L

                 Free NMN   Free MN   Free MT   Total NMN   Total MN

May 2008
July 2008           0.26      0.24     2.78#        4.36       3.37
September 2008      0.37      0.21     <0.03        6.60       2.70
May 2009            0.37      0.20     <0.03
July 2010           0.29      0.21      0.04        6.73       3.39
February 2011       0.37      0.18     0.10#       10.70       5.70
URL                <1.39     <0.85     <0.06      <26.20      <9.61

Date                       Plasma, nmol/L

                 Total MT   NE      E       DA

May 2008
July 2008         26.90#     2.25    0.24   20.46#
September 2008      2.55     0.91    0.16     0.20
May 2009                     0.83    0.12     0.04
July 2010           2.93     1.60    0.25     0.24
February 2011      3.68#     2.08    0.22     0.11
URL                <2.99    <6.55   <1.23    <0.38

(a) The tumor was removed in August 2008. Boldface
numbers are abnormal values.

(b) NMN, normetanephrine; MN, metanephrine; MT, methoxytyramine;
NE, norepinephrine; E, epinephrine; DA, dopamine; URL, upper
reference limit.

Note: Abnormal values are indicated with #.
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Article Details
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Title Annotation:the Clinical Chemist: What Is Your Guess?
Author:Puder, Jardena; Stadelmann, Raphael; Schoettker, Patrick; Buclin, Thierry; Grouzmann, Eric
Publication:Clinical Chemistry
Article Type:Case study
Date:Aug 1, 2013
Words:691
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