The diagnosis of CSID/genetic sucrase deficiency can be missed, especially if patients have mild, nonspecific symptoms that resemble other, more common gastrointestinal diseases. Common misdiagnoses may include toddler’s diarrhea, diarrhea-predominant irritable bowel syndrome (IBS), or recurrent abdominal pain-predominant IBS.
CSID is often difficult to diagnose. In most cases of CSID, correct diagnosis is delayed while other more common causes of severe, chronic diarrhea are considered. Once infancy is passed and a larger variety of foods are added to the diet, it is more difficult to correctly identify sucrose malabsorption as the primary cause of symptoms. Allergic gastroenteropathy, cystic fibrosis, celiac disease, severe viral gastroenteritis, lactose intolerance, glucose–galactose intolerance, or other causes of intractable diarrhea are often considered potential diagnoses, as they all have similar symptoms to CSID.
Infants may go through several formula changes while in the diagnosis stage. An allergy to cow’s milk or soy protein allergy may be considered.