Body Mass Index (BMI) Charts

Board takeaway

• Interpret: Interpret pediatric BMI by age and the appropriate sex-specific chart, not by the BMI number alone.
• Age range: The AAPD resource reproduces CDC charts for ages 2–20 years, including extended curves at very high BMI.
• Document: Record the chart and the plotted values so another clinician can follow the interpretation.

Choose and document the chart

• Both forms provide fields for patient name and record number.
• The horizontal axis is age in years; the vertical axis is BMI in kg/m².
• Practical documentation: identify the patient, use the appropriate form, and record the age and BMI used for plotting. Retain the chart with the encounter documentation.
• Read the curve labels before assigning a percentile. Both charts include a dotted 120% of the 95th percentile line; this is a percentage of a BMI reference value, not a “120th percentile.”

Keep BMI interpretation separate from treatment decisions

• These CDC charts were published December 15, 2022.
• They display BMI-for-age percentiles; they do not determine a dental treatment plan, a drug dose, or referral urgency.
• Use the patient’s broader medical assessment for those decisions.

Common board traps

Answer aloud

How do you use a pediatric BMI chart, and what are its limits?

Plot BMI against age on the appropriate sex-specific chart for ages 2–20 years.

• Record patient identifiers, age, BMI, and the chart used; a BMI number alone does not give a pediatric percentile.
• Read the labeled curves, including the extended high-BMI curves.
• The chart supports medical assessment but supplies no dental-treatment or drug-dosing rule.

Is 120% of the 95th percentile a 120th percentile?

No. It is a percentage of the BMI value on the 95th-percentile reference curve.

• Both charts show this dotted line.
• Distinguish reference-BMI percentages from percentile ranks before interpreting a very high BMI.