Secondary lactase deficiency

This code signifies a condition where the small intestine produces insufficient lactase, the enzyme needed to digest lactose, as a result of damage to the intestinal lining from another underlying disease or injury. Unlike primary lactase deficiency, this form is acquired and often reversible once the underlying cause is treated. Patients typically experience gastrointestinal symptoms such as bloating, gas, and diarrhea after consuming lactose-containing foods.

Use this code when documentation clearly indicates lactase deficiency is secondary to another condition, such as celiac disease, Crohn's disease, gastroenteritis, or intestinal surgery. This diagnosis is supported by patient history of an underlying gastrointestinal disorder and symptoms consistent with lactose intolerance following lactose ingestion.

• Always code the underlying cause of the intestinal damage first, as this is a secondary diagnosis.
• Distinguish carefully from primary (congenital or developmental) lactase deficiency, which has a different code.
• Ensure documentation specifies "secondary" or an underlying cause is identified to support this code.