Best screening test for pheochromocytoma?

Ans: a (Urinary VMA estimation)Ref: Vasudevan & Sreekumari, 6th edi., Pg. 207Vanillyl mandelic acid (VMA) in urineVMA is the main urinary metabolite of the norepinephrine pathway. Metanephrine is acted upon by mono amine oxidase to form(VMA). Normal level of excretion of VMA is 2-6 mg/24 hr.lt is increased in pheochromocytoma and in neuroblastoma.Patient is asked to refrain from intake of chocolate, coffee, banana, vanilla ice creams, citrus fruits (lime & orange). These items contain vanillin, which produces very high value of VMA in urine. Patient should not take aspirin or drugs containing phenol ring.Homovanillic acid (HVA) in urine: HVA is the main urinary metabolite of dopa and dopamine pathway It is increased in neuroblastoma, malignant pheochromocytoma and ganglioneuroma.It is useful to predict prognosis of neuroblastoma. Drugs increasing the value are -L-dopa, disulfiram and reserpine.