Pediatric Coding Alert

Reader Question:

Know When Patient Age Carries Weight for Reporting BMI

Question: An obese patient with gastrointestinal issues came in to see the pediatrician the other day, and the pediatrician suspects the patient’s obesity is related to the stomach problems. However, the patient is 18. Should I code the BMI with the adult code or the pediatric code?

Georgia Subscriber

Answer:  Even though an 18-year-old is often considered a technical adult, the Body Mass Index (BMI) (Z68) section of the ICD-10 explains that BMI adult codes are for patients 20 years of age or older and BMI pediatric codes are for patients ages 2 to 19. Therefore, an 18-year-old patient’s BMI would be reported using one of the following pediatric codes:

  • Z68.51 (Body mass index [BMI] pediatric, less than 5th percentile for age)
  • Z68.52 (Body mass index [BMI] pediatric, 5th percentile to less than 85th percentile for age)
  • Z68.53 (Body mass index [BMI] pediatric, 85th percentile to less than 95th percentile for age)
  • Z68.54 (Body mass index [BMI] pediatric, greater than or equal to 95th percentile for age)

You will have to line up the patient’s age and BMI in the growth chart published by the Centers for Disease Control and Prevention (CDC) to find the correct percentile, and that will lead you to the correct code. (

Reminder: BMI codes “should only be assigned when there is an associated reportable diagnosis (such as obesity)” (emphasis retained), according to ICD-10 Guideline 1.C.21.c.3. In this question, obesity is a factor, as is a potentially related condition, so BMI is appropriate to report.

However, if the pediatrician did not include the BMI in the patient record for the described encounter, you’ll want to check in with them for that information. While you will have to check the chart to arrive at the correct percentile, it’s not recommended you calculate BMI based only on documented height and weight.