Since catecholamines levels may fluctuate significantly during a period of time, measuring urine catecholamines released in 24 hours may detect excess production that is missed with the blood test. The rate of elimination of catecholamines in urine reflects the rate of synthesis in the periphery. Plasma and urine tests may be ordered together or separately to look for excessive amounts of both catecholamines and their metabolites. See Catcholamines Fractionation (Adrenaline, Noradrenaline, and Dopamine).
Add HCl as preservative, pH 4-6. Observe diet and discontinue interfering drugs. State 24 Hrs urine volume.