Mibg scan normal metanephrines high.

I was referred for mibg scan after elevated levels of metanephrines and nor metanephrines in my plasma test. The mibg scan didn't reveal anything abnormal. I have hypertension for past 7 years and have been under medications for the same. I also was diagnosed with anxiety disorder 4 years back and face panic attacks on daily basis. Apart from panic attacks I have persistent headaches and occasional chest pains. I have been advised by one of endocrinologist to undergo Plasma aldosterone- plasma renin ratio blood test. Wanted to know difference between the metanephrines test and aldosterone test and is there any possibility of some other tumor other than pheochromocytoma having similar symptoms?