This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of Adrenal Gland, Subject name: Medicine
A 45 year old male presented with palpitations, tachycardia & anxiety. His BP is 158/90 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? 
Select and explain. 
A. Hold labetalol for 1 week and repeat testing, B. Hold citalopram for 1 week and repeat testing, C. Refer immediately for surgical evaluation, D. Measure 24-hour urine vanillylmandelic acid level
A: Hold labetalol for 1 week and repeat testing
Answer: A: Hold labetalol for 1 week and repeat testing 
Explanation: 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