Correspondence

Effect of Buspirone on Urinary Catecholamine Assays

N Engl J Med 1995; 332:401February 9, 1995

Article

To the Editor:

Many medications interfere with the assays for catecholamine metabolites in urine that are used to evaluate patients suspected of having a pheochromocytoma.1,2 We report the effect of buspirone, a commonly used anxiolytic agent, on these assays.

A 49-year-old man with a four-year history of hypertension was referred for evaluation for a possible pheochromocytoma. He had a one-year history of episodic anxiety, dizziness, and palpitation that improved when he lay down. He was treated with buspirone (5 or 10 mg three times a day), with some improvement. He also had hypertension, which was treated with amlodipine (5 mg once a day). His blood pressure at the time of our evaluation was 190/100 mm Hg when he was supine, 175/95 mm Hg when he was sitting, and 165/95 mm Hg when he was standing; the physical examination was otherwise normal. Urinary normetanephrine excretion was normal (305 μg per day) and the metanephrine excretion was grossly elevated (4849 μg per day; see Table 1Table 1Urinary Values for Catecholamines and Cathecholamine Metabolites in Subjects Receiving Buspirone. for normal values). Urinary vanillylmandelic acid (VMA) and catecholamines were not measured. The amlodipine was continued, but the buspirone was discontinued. A 24-hour urine sample collected 48 hours later contained 166 μg of metanephrine. Urinary VMA, normetanephrine, and catecholamine values were also normal in this specimen.

To confirm that buspirone interferes with the metanephrine assay, two of us collected 24-hour specimens of our own urine before the administration of 10 mg of buspirone three times daily, again on the second day of this treatment, and three days after buspirone was discontinued (Table 1). When it was assayed in a different laboratory by the same chromatographic method3 that was used to study the samples from the patient, the second sample contained material that eluted with metanephrine. Presumably, this material was a metabolite of buspirone, because the addition of buspirone in vitro did not cause the same chromatographic artifact and the metanephrine values in the other two samples from each subject were normal.

Buspirone is commonly prescribed for patients with panic or anxiety attacks. These symptoms may prompt screening for pheochromocytoma, particularly if the patient also has hypertension. Our observations indicate the buspirone should be added to the list of medications that interfere with assays for urinary metanephrine.

Fiona Jackson Cook, M.D.
East Carolina University School of Medicine, Greenville, NC 27858

Donald Walt Chandler, Ph.D.
Endocrine Sciences, California, Calabasas Hills, CA 91301

David K. Snyder, M.D.
East Carolina University School of Medicine, Greenville, NC 27858

3 References

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   Becker KL. Principles and practice of endocrinology and metabolism. Philadelphia: J.B. Lippincott, 1990:678.
   

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   Shoup RE, Kissinger PT. Determination of urinary normetanephrine, metanephrine, and 3-methoxytyramine by liquid chromatography, with amperometric detection. Clin Chem 1977;23:1268-1274
   Web of Science | Medline

Citing Articles (4)

Citing Articles

1. 1

   Takahiro Ito, Tsuneo Imai, Toyone Kikumori, Arihiro Shibata, Takao Horiba, Hironobu Kobayashi, Masataka Sawaki, Reiko Watanabe, Akimasa Nakao, Tetsuya Kiuchi. (2006) Adrenal Incidentaloma: Review of 197 Patients and Report of a Drug-Related False-Positive Urinary Normetanephrine Result. Surgery Today 36:11, 961-965
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2. 2

   Sang Wan Kim, Kyung Won Kim, Do Joon Park, Chan Soo Shin, Kyung Soo Park, Seong Yeon Kim, Bo Youn Cho, Hong Kyu Lee. (2005) Diagnostic Value of 24-hours Urinary Total Metanephrine As a Screening Test of Patients with Suspected Pheochromocytoma. Journal of Korean Society of Endocrinology 20:1, 12
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3. 3

   Farhad Elmi, Benjamin Quintana, Aram Yousefi. (2000) Difficult-to-Control Hypertension. Mayo Clinic Proceedings 75:6, 655
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4. 4

   Richard I. Shader. (1996) Question the Experts. Journal of Clinical Psychopharmacology 16:2, 194
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