<prompt> A 45 year old male presented with palpitations, tachycardia anxiety. His BP is 15890 mmHg. The patient also has mild depression and is presently taking citalopram, labetalol amlodipine to control his blood pressure. 24-hour urine total metanephrines are ordered and show an elevation of 1.5 times the upper limit of normal. What is the next best step?Hold labetalol for 1 week and repeat testingHold citalopram for 1 week and repeat testingRefer immediately for surgical evaluationMeasure 24-hour urine vanillylmandelic acid level  <response>: Investigations done in pheochromocytoma 24 hour urinary fractionated metanephrine 24 hour urinary catecholamines 24 hour urinary vanillylmandelic acid level IOC- Plasma fractionated metanephrine levels 24-hour urine total metanephrines has high sensitivity value of three times the upper limit of normal is highly suggestive of pheochromocytoma. Borderline elevation- likely to be false positives. Drugs related- include levodopa, sympathomimetics, diuretics, TCA, and a- and b-blockers Labetalol Therefore, hold labetalol for 1 week and repeat testing is the best next step 