Congenital Sucrase-Isomaltase Deficiency (CSID)

Congenital sucrase-isomaltase deficiency (CSID) is an inherited disorder that affects a person's ability to digest certain sugars. People with this condition cannot break down the sugars sucrose (also known as table sugar) and maltose (the sugar found in grains).

The prevalence of CSID is estimated to be between 1/500 and 1/2 000 among individuals of European descent. In the native populations of Greenland, Alaska, and Canada the condition is more prevalent, where as many as 1 in 20 people may be affected.

Chronic diarrhea and abdominal pain are common symptoms of CSID

Symptoms of people with CSID can vary between individuals and range from mild to severe chronic watery diarrhea, gas, bloating and stomach cramps. The symptoms usually become apparent after an infant starts to consume sucrose- and starch-containing foods (e.g. fruits, juices, grains or medications sweetened with sucrose) and can lead to malnutrition and failure to gain weight and grow at the expected rate (failure to thrive).

Most affected children are better able to tolerate sucrose and maltose as they get older, but CSID is not a disease that a person 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.

Diagnosis of CSID is often delayed

CSID could be difficult to diagnose, especially if patients have mild, nonspecific symptoms that resemble other, more common gastrointestinal diseases. Allergic gastroenteropathy, cystic fibrosis, celiac disease, diarrhea-predominant irritable bowel syndrome (IBS), 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.

Methods to aid in the diagnosis of CSID are enzyme analysis of small bowel biopsy, genetic testing or sucrose hydrogen breath test.

Dietary restrictions are the primary treatment option for CSID

Treatment of CSID consists primarily of reducing the amount of sucrose and starch in the diet. Since the clinical presentation of CSID is variable the nutritional needs will differ between individuals and regular follow-up on dietary advice is crucial to provide the best outcome.



National Library of Medicine (NLM)
Treem WR. Congenital sucrase-isomaltase deficiency. J Pediatr Gastroenterol Nutr. 1995;21:1-14
McMeans A. Congenital sucrase-isomaltase deficiency: Diet assessment and education guidelines