William,
My NEC Carotid Body Paraganglioma was active. Till NEC diagnosis I have been miss-diagnosed twice.
First I have not slept without medication for over 10 years. No sleep apnea, been through three sleep clinics, nothing.
Second big one started about 2.5 years ago. Blood pressure spikes and drops. Highest I have had was 245 over 187. They did a stress test, EKG, etc., basically I have a heart like a horse. Lowest has been 88 over 65.
I had lower abdominal pains for over 3 years. Miss-diagnosed with liver disease. Turns out my CBT and my SDHB mutation targets kidneys and liver to grow cysts.
I May of this year, my primary care has moved. My new primary care is an amazing old school doctor (no iPad). During the physical he felt ant noticed a bump in my neck about an inch below left ear or little more. Just to be safe he ordred an Ultra sound. Based on findings I had to have a CT scan two days after, MRI, and than Dotatate PetCT scan. So they found it completely by accident.
They ordered an additional abdominal scan and thats when they found two cysts in the liver and two stones. Stones were causing pain. Finally I had a logical explanation tht made sense. Kidney surgery went super well, I was walking by 4th of July.
I am not a fan of the blood/urine hormone level tests by themselves. If you have an active paraganglioma or pheocromocytoma, ask any doctor, endo or other, what causes them to secrete. Nobody knows. I got a good answer from Karolinka Institute in Sweden, they feel that stress factors and trigger play a role in these tumor secretin. They just do it more. 24 hour urine or your one time blood test when you are relaxed and not doing anything do not paint a complete picture. There are some trigger factors that are known. Good urologist may have trick. For pheochromocytoma, it is a fact that an early diabetes test with glucose tolerance will make your pheo spike. Blood pressure will jump. I spoke with a professor here at UT Medical who has witnessed it twice. But, trigger testing is a taboo. Not sure why. I was told they do not trigger test from Mayo Edno, Clevelnd Clinic PG and PC clinic and MD Anderson in Houston.

Sorry for the long post. Best of luck!