Hi Natnels- My daughter had elevated fecal calprotectin. It tested at 380, so her GI thought she had crohn's. But her endoscopy, colonoscopy, biopsies and MRI Enterography (MRE) all came back negative, so she does not seem to have crohn's, at least not now.
From what I can glean through much research and discussion with GI's, is that fecal calprotectin is a useful diagnostic tool to suggest that further testing is necessary. If you already have a diagnosis it is a useful marker to suggest when activity is present. But by itself with no other indications, it does not definitely mean that you have inflammation present.