Understanding & navigating
What we’ve learned about Congenital Sucrase-Isomaltase Deficiency — from first symptoms to daily management.
Congenital Sucrase-Isomaltase Deficiency (CSID) is a rare genetic condition where the body cannot properly digest certain sugars — specifically sucrose (table sugar) and maltose. The small intestine lacks sufficient activity of the enzymes sucrase and isomaltase, which are needed to break these sugars down into simpler forms the body can absorb. When these sugars aren't digested, they pass into the large intestine where bacteria ferment them, causing uncomfortable GI symptoms.
The symptoms that first caught our attention included chronic diarrhea, excessive gas and bloating, abdominal pain and cramping — especially after meals — irritability around eating times, and difficulty gaining weight. These symptoms often appeared or worsened after eating foods containing sucrose or starch. It took time to connect the dots, as many of these symptoms overlap with other common childhood conditions.
Getting to a CSID diagnosis was a process. Initial visits focused on ruling out more common conditions like lactose intolerance, celiac disease, and food allergies. The key diagnostic step was a disaccharidase assay — a test performed on a small biopsy of the intestinal lining taken during an endoscopy. This test measures the activity levels of sucrase, isomaltase, and other digestive enzymes. When sucrase activity came back significantly low, we had our answer.
The primary treatment for CSID is Sucraid (sacrosidase), an enzyme replacement therapy taken orally with meals and snacks. Sucraid provides the sucrase enzyme that the body is missing, allowing sucrose to be properly digested. It's taken as a liquid — measured with a small syringe and mixed into a few sips of water or taken directly. Alongside Sucraid, dietary management plays an important role. Learning which foods are well-tolerated and which ones cause problems has been an ongoing process.
Day-to-day life with CSID means being thoughtful about food, but it doesn't mean missing out. We've learned to read labels carefully, find recipes that work, and communicate with schools and caregivers about dietary needs. Sucraid has been a game-changer — it allows for a much more flexible diet than would otherwise be possible. There are still challenging days, but each one teaches us something new. The CSID community, though small, has been an incredible source of support and shared knowledge.
Patient support and education from the makers of Sucraid, including recipes and community resources.
National Organization for Rare Disorders page on CSID with medical overview and support information.
Pediatric gastroenterology resources for families navigating digestive conditions.
Online communities and social media groups where families share experiences, tips, and support.