Investigations

If a phaeochromocytoma is suspected ^c

• plasma catecholamines
• 24h urine for catecholamine breakdown products

Why?

Raised plasma and urine catecholamines make a phaechromocytoma more likely

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
suspected phaechromocytoma c (pre-test probability: 6.3%)	phaechromocytoma (histology or follow-up)	plasma catecholamines > 950 pg/ml	13 (8.3 to 20)	47%	0.24 (0.12 to 0.50)	1.6%
		urinary metanephrines > 1.8 mg/24 hours	6.9 (4.7 to 10)	32%	0.34 (0.19 to 0.61)	2.2%
		urinary vanillylmandelic acid (VMA) > 11 mg/24 hours	16 (9.7 to 26)	51%	0.24 (0.12 to 0.49)	1.6%