Biochemical and radiological features of pheochromocytoma

Pheochromocytomas (PHEOs) are catecholamine-producing neuroendocrine tumours and can cause life-threatening hypertensive crises. An elevation (> 4-fold above the upper limit of normal (ULN)) of fractionated metanephrine (MN) and nor-metanephrine (NMN), collectively called metanephrines (MN and NMN), either in plasma or urine are the most sensitive tests for the diagnosis of PHEO. There are a greater number of false positive results when the elevations are more modest.

Kannan et al. retrospectively reviewed the charts of patients with and without PHEO in order to identify biochemical and radiological features in PHEOs with modest elevations (< 4-fold above ULN) of metanephrines.

They found that modest elevations (< 4-fold ULN) of the NMN fraction in an adrenal mass > 5 cm are almost always falsely positive. Elevations in plasma and urinary MN fraction are less likely to be false positive. The CT pre-contrast attenuation of PHEOs is > 10 HU.

Read full article at Kannan et al. (2014) Clinical Endocrinology 80 (6) 790-796; DOI: 10.1111/cen.12420