Body Mass Index (BMI) ICD-10-CM codes

Z68 codes are secondary codes only, and they may only be reported when the provider has documented an associated weight diagnosis such as E66.9 (obesity), E66.01 (morbid obesity due to excess calories), the class-based codes E66.811 through E66.813, E66.3 (overweight), R63.6 (underweight), or a malnutrition code such as E44.0. A BMI code with no paired diagnosis is not reportable, and a BMI in the vital signs does not by itself establish obesity. The reverse also applies: E66.x without a Z68 code is incomplete on most quality measures and HCC reviews.

The guidelines (section I.B.14) allow the BMI value to be taken from documentation by any clinician, including a nurse or dietitian, but the associated diagnosis must come from the patient's provider. Adult codes (age 20 and older) run from Z68.18 (18.4 or less) and Z68.19 (18.5 to 19.9) through Z68.20 to Z68.29, Z68.30 to Z68.39, and the higher ranges Z68.41 (40.0 to 44.9), Z68.42 (45.0 to 49.9), Z68.43 (50.0 to 59.9), Z68.44 (60.0 to 69.9), and Z68.45 (70 or greater). Pediatric patients aged 2 to 19 use the percentile codes Z68.51 through Z68.56, where Z68.54, Z68.55, and Z68.56 grade obesity from the 95th percentile up through 140 percent of the 95th percentile.

BMI codes are not reported during pregnancy; the chapter 15 obesity code O99.21x is used with E66.x instead. They are also not reported when the weight condition is clinically irrelevant to the encounter, so a BMI of 31 noted at a laceration repair with no obesity diagnosis stays off the claim. Obesity counseling for Medicare (G0447) requires E66.x with a Z68.3x or higher code showing a BMI of 30 or more.

Z68 changes over time as weight changes, so pick the code matching the BMI in the current note rather than carrying forward last year's value. When the BMI falls in the normal range and there is no weight diagnosis, no Z68 code is reported at all.