A. There are tests for lactose intolerance that are easy to do. IBS is basically a ‘rule-out’ condition; it is the label given for chronic GI problems the doctor can’t find a cause for. Before a patient is labeled as having IBS, they should have been tested to rule out a number of other conditions, including celiac disease. The blood tests for celiac disease are very sensitive and specific so it is unlikely that you would ever get a false-positive result.