Diagnosis of Phaeochromocytomas and Secretory Paragangliomas



Sources of interference with measurements of catecholamines and catecholamine metabolites - from Lenders et al 2005.
HPLC=high-pressure liquid chromatography
Analytical methods
Coffee (including decaffeinated coffee) HPLC assays: plasma catecholamines
Labetalol Spectrophotometric and fluorometric assays: urinary catecholamines and metanephrines
Sotalol HPLC assays: plasma catecholamines
Buspirone HPLC assays: urinary metanephrines
Paracetamol HPLC assays: plasma-free metanephrines
Levodopa HPLC assays: catecholamines and metabolites
α-methyldopa HPLC assays: catecholamines
Sympathomimetics (eg, amphetamines, ephedrine) Spectrophotometric and fluorometric assays: plasma and urinary catecholamines
Pharmacodynamic or pharmacokinetic interference
Tricyclic antidepressants Block norepinephrine reuptake, causing rises in plasma and urinary norepinephrine, normetanephrine, and VMA
Phenoxybenzamine Blocks presynaptic α2 adrenoceptors, causing increases in plasma and urinary norepinephrine, normetanephrine, and VMA
MAOI Block deamination, causing up to five-fold increases in plasma and urinary metanephrines
Levodopa Metabolised by enzymes that also convert catecholamines
Methyldopa Metabolised by enzymes that also convert catecholamines
Stimulants (eg, caffeine, nicotine) Increased plasma and urinary catecholamines
Sympathomimetics (eg, amphetamines, ephedrine) Increased plasma and urinary catecholamines
Calcium-channel blockers (dihydropyridines) Increased plasma catecholamines due to sympathetic activation
Likelihood of presence of phaeochomocytoma for various levels of biochemical results - from Lenders, Lancet 2005 366 665