Body Mass Index less than 19, adult

This code indicates an adult patient whose Body Mass Index (BMI) falls below 19. A BMI under 19 is generally considered underweight and can be associated with various health concerns, including malnutrition, eating disorders, or underlying medical conditions.

Apply this code when documentation clearly states an adult patient's BMI is less than 19. This is often seen in cases of unexplained weight loss, assessment for nutritional deficiencies, or monitoring patients with conditions that affect weight.

• Always ensure the patient is an adult; pediatric underweight has different codes.
• Document the actual BMI value in the patient's record to support the code.
• Code any underlying conditions contributing to the low BMI, such as anorexia nervosa or chronic disease, as primary diagnoses if applicable.