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1. Fractionated metanephrines and catecholamines in 24-hour urine (preferred for screening of low-risk individuals).

2. Patients should be weaned off of tricyclic antidepressants and cyclobenzaprine 2 weeks before testing because these meds interfere with the results (SSRIs are okay).

3. Plasma fractionated metanephrines; sensitivity is high, so a negative test excludes disease.

4. However, specificity is low, so measure these only in patients who carry a high pretest probability of disease (MEN2/NFNHL, incidentaloma with characteristics of pheo, or family Hx of pheo).

5. For the patient with a possible false-positive result and an increase in plasma fractionated metanephrines, a clonidine suppression test can be performed.


1. Wilkinson, I. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press.
2. Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
3. Image: no reference available.

Ⓒ A. Manickam 2018

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