PHAEOCHROMOCYTOMA-INVESTIGATION

SUMMARY

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.

Reference(s)

Wilkinson, I., Furmedge, D. and Sinharay, R. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press. Get it on Amazon.
Feather, A., Randall, D. and Waterhouse, M. (2020). Kumar And Clark’s Clinical Medicine. 10th ed. S.L.: Elsevier Health Sciences. Get it on Amazon.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].