Having a high count on Chromogranin is indicative of a Neuroendocrine tumor, regardless of whether or not it came up on a Gallum 68 test. There are many different types of this test and one may not be adequate or accurate as another. I would suggest starting a regiment of Sandostatin ( Octreotide Acetate) if your wife's symptoms are in line with this kind of tumor. Look up Carcinoid.org to find the latest symptom list and should your wife have these kinds of problems, I would ask to be put on 30mgLR Sandostatin to see if her symptoms improve.
Best of luck
Ken