E74.31 Sucrase-isomaltase deficiency

Name of the Condition

• Sucrase-isomaltase deficiency (ICD-10 Code E74.31)

Summary

Sucrase-isomaltase deficiency is a rare inherited disorder that impairs the small intestine's ability to digest and absorb certain carbohydrates, specifically sucrose (table sugar) and starches containing isomaltose. This condition results from a deficiency of the sucrase-isomaltase enzyme, leading to malabsorption of these sugars and subsequent gastrointestinal symptoms. The disorder typically presents in infancy or early childhood but may be diagnosed later in life.

Causes

Sucrase-isomaltase deficiency is caused by genetic mutations that affect the production or function of the sucrase-isomaltase enzyme. These mutations are usually inherited in an autosomal recessive pattern, meaning an individual must inherit two copies of the mutated gene (one from each parent) to develop the condition. The enzyme deficiency disrupts the breakdown of sucrose and isomaltose, preventing their absorption in the small intestine.

Risk Factors

• Genetic predisposition or family history of sucrase-isomaltase deficiency.
• Consanguinity (parents who are closely related), increasing the likelihood of inheriting recessive mutations.
• Ethnic or population-specific prevalence for certain genetic variants associated with the disorder.

Symptoms

Symptoms typically include chronic diarrhea, abdominal pain, bloating, and excessive gas (flatulence) after consuming foods containing sucrose or starch. Other possible symptoms are:

• Failure to thrive or poor weight gain in infants and children.
• Dehydration or electrolyte imbalances due to persistent diarrhea.
• Irritability or fussiness, particularly in young children.
• Malnutrition or vitamin deficiencies if the condition is untreated.

Diagnosis

Diagnosis is based on clinical presentation, dietary history, and specialized testing. A healthcare provider may order a hydrogen breath test after sucrose ingestion, which measures elevated hydrogen levels indicative of malabsorption. Intestinal biopsy with enzyme activity testing can confirm the deficiency. Genetic testing may identify the specific mutations responsible for the disorder.

Treatment Options

Treatment focuses on managing symptoms and preventing malabsorption. Dietary modifications are the primary approach, typically involving a sucrose-restricted diet and avoidance of starches high in isomaltose. Enzyme replacement therapy with sucrase supplements may be used in some cases. Nutritional support, including vitamin and mineral supplementation, is often necessary to address deficiencies. Regular monitoring by a healthcare provider ensures adequate growth and development.

Prognosis and Follow-Up

With proper dietary management, most individuals with sucrase-isomaltase deficiency can lead healthy lives and achieve normal growth and development. Early diagnosis and adherence to a restricted diet improve outcomes. Long-term follow-up with a gastroenterologist or metabolic specialist is recommended to monitor nutritional status, adjust the diet as needed, and address any complications. Lifelong dietary management is typically required.

Complications

Untreated or poorly managed sucrase-isomaltase deficiency can lead to:

• Severe malnutrition and growth failure in children.
• Chronic dehydration or electrolyte imbalances.
• Developmental delays due to persistent nutrient deficiencies.
• Increased risk of dental caries (cavities) from residual sugars in the mouth.

Lifestyle & Prevention

Lifestyle management centers on strict adherence to a sucrose- and isomaltose-restricted diet. Reading food labels carefully to avoid hidden sugars and starches is essential. Working with a registered dietitian can help create a balanced meal plan that meets nutritional needs while avoiding trigger foods. Preventive measures include educating caregivers, schools, and others about the dietary restrictions to avoid accidental exposure.

When to Seek Professional Help

Seek medical attention if symptoms such as persistent diarrhea, unexplained weight loss, or failure to thrive occur, especially after consuming sugary or starchy foods. Immediate care is needed for signs of dehydration, such as dry mouth, reduced urination, or lethargy. Regular follow-up with a healthcare provider is important for monitoring growth, nutritional status, and adjusting treatment as the individual ages.

Tips for Medical Coders

When coding for sucrase-isomaltase deficiency, use ICD-10-CM code E74.31. Ensure documentation supports the diagnosis, including clinical findings (e.g., symptoms, dietary history), diagnostic test results (e.g., breath test, biopsy), and any genetic testing. Note that this code is specific to sucrase-isomaltase deficiency and should not be used for other carbohydrate absorption disorders. Verify that the code aligns with the patient's documented condition and treatment plan.