What Are Symptoms of Genetic Sucrase-Isomaltase Deficiency/Congenital Sucrase-Isomaltase Deficiency?

Symptoms of patients with Genetic Sucrase-Isomaltase Deficiency/Congenital Sucrase-Isomaltase Deficiency can range from mild to severe chronic, watery, acidic diarrhea; gas; bloating and abdominal pain.1 Infants do not manifest symptoms of Genetic Sucrase-Isomaltase Deficiency until they begin to ingest sucrose- and starch-containing foods (e.g., juices, solid foods, medications sweetened with sucrose). Chronic, watery diarrhea and failure to thrive are the most common symptoms in infants and toddlers; other symptoms include abdominal distention, gassiness, colic, irritability, excoriated buttocks, severe diaper rash due to the acidic diarrhea, dyspepsia and vomiting. In some societies, notably Greenland Eskimo and some Alaskan Native, a low-carbohydrate, high-protein, high-fat diet may mask symptoms. A small number of patients may require hospitalization for diarrhea and dehydration, malnutrition, muscle wasting and weakness.2 Patients with confirmed Genetic Sucrase-Isomaltase Deficiency commonly report being examined for Toddler’s Diarrhea/IBS-D, Celiac Disease, Cystic Fibrosis and food allergies.

Presenting symptoms in twenty-three patients with CSID 3

In adults, symptoms persist, but may appear to be less severe than those experienced by children. Genetic Sucrase-Isomaltase Deficiency is not a disease that a patient can “outgrow”. In some adults, symptoms may be limited to an increase in bowel frequency, abdominal distention and flatulence, although episodic watery diarrhea upon ingestion of high levels of sucrose may occur.3 In some patients, diarrhea may alternate with constipation, leading to a misdiagnosis of Irritable Bowel Syndrome (IBS).

As with pediatric patients, the clinical presentation in adults is variable. With the introduction of dietary sucrose, some patients may experience several severe effects from this disease, while others may experience only mild symptoms.

Sucrose Digestion



  1. Antonowicz I, Lloyd-Still JD, Khaw KT, Shwachman H. Congenital sucrase-isomaltase deficiency. Observations over a period of 6 years. Pediatrics. 1972;49:847-853.
  2. Gudmand-Hoyer E. Sucrose malabsorption in children: a report of thirty-one Greenlanders. J Pediatr Gastroenterol Nutr. 1985;4:873-877.
  3. Treem WR. Congenital sucrase-isomaltase deficiency. J Pediatr Gastroenterol Nutr. 1995;21:1-14.
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