E73.0 Congenital lactase deficiency

Name of the Condition

• Congenital Lactase Deficiency (ICD-10 Code: E73.0)

Summary

Congenital lactase deficiency is a rare genetic disorder characterized by the absence or severe reduction of lactase enzyme activity from birth. This enzyme is essential for breaking down lactose, the sugar in milk and dairy products. Infants with this condition cannot digest lactose, leading to gastrointestinal symptoms shortly after consuming breast milk or formula. The condition is distinct from lactose intolerance, which typically develops later in life.

Causes

The disorder is caused by mutations in the LCT gene, which provides instructions for producing lactase. These genetic changes result in little to no functional lactase enzyme, preventing lactose digestion. It is inherited in an autosomal recessive pattern, meaning both parents must carry a copy of the mutated gene for a child to be affected.

Risk Factors

• Family history of congenital lactase deficiency.
• Consanguineous relationships (parents who are closely related), increasing the likelihood of inheriting two mutated genes.

Symptoms

• Severe diarrhea, often starting within days of birth.
• Abdominal bloating and cramping.
• Vomiting and failure to gain weight.
• Dehydration and electrolyte imbalances in severe cases.

Diagnosis

Diagnosis is based on clinical presentation, including symptoms after lactose exposure, and confirmed through laboratory tests. Stool acidity tests may show low pH due to undigested lactose fermentation. Genetic testing for LCT gene mutations can provide definitive confirmation.

Treatment Options

• Elimination of lactose from the diet, typically using lactose-free infant formulas or soy-based alternatives.
• Close monitoring of nutritional intake to ensure adequate growth and development.
• In some cases, enzyme supplements may be considered, though dietary modification is the primary approach.

Prognosis and Follow-Up

With early diagnosis and strict lactose avoidance, infants can thrive and develop normally. Long-term prognosis is excellent when dietary management is maintained. Regular follow-up with a pediatrician or gastroenterologist is recommended to monitor growth and adjust the diet as needed.

Complications

• Malnutrition and growth failure if lactose is not promptly removed from the diet.
• Severe dehydration and electrolyte disturbances in untreated cases.
• Potential for developmental delays if nutritional deficiencies are not addressed.

Lifestyle & Prevention

• Strict adherence to a lactose-free diet is critical to prevent symptoms.
• Parents and caregivers should be educated on reading food labels to avoid hidden lactose in processed foods.
• Breastfeeding may require supplementation with lactase-free milk or alternative feeding methods.

When to Seek Professional Help

• Persistent diarrhea, vomiting, or poor weight gain in infants.
• Signs of dehydration, such as reduced urination, dry mouth, or lethargy.
• Unexplained abdominal pain or bloating after consuming dairy products.

Tips for Medical Coders

• Code E73.0 is specific to congenital lactase deficiency and should not be used for other lactose-related conditions.
• Documentation should clearly indicate the onset (congenital) and confirmatory testing (e.g., genetic or stool tests) to support the diagnosis.
• Ensure the code is applied only when the condition is present from birth and not confused with secondary lactase deficiency or lactose intolerance.