The “Catecholamine Level – Plasma (OS)” test measures stress hormones (epinephrine, norepinephrine, dopamine) in your blood, helping diagnose rare tumors like pheochromocytoma or neuroblastoma, or conditions causing excess adrenaline release, by checking for abnormally high levels linked to symptoms like severe headaches, palpitations, anxiety, and high blood pressure, often done with blood drawn after fasting and avoiding stress