Malnutrition, Obesity and Body Mass Index (BMI): Coding Guidelines

Good nutrition is essential to prevent and manage diseases and to keep people live longer. Malnutrition is a condition that occurs when the body does not get enough nutrients. The World Health Organization defines malnutrition as the “deficiencies, excesses, or imbalances in a person’s intake of energy and/or nutrients”. Obesity or overweight is the other side of the coin. Being overweight makes people prone to various chronic illnesses, including cardiovascular disease, type 2 diabetes and even some cancers. ICD-10 offers codes and guidelines to report severe malnutrition and obesity. Complete and accurate documentation is necessary for medical billing and coding service providers to ensure appropriate code assignment and claim submission.

While the problem of malnutrition in the US is not as pervasive as in many other countries, it is a devastating reality and the COVID-19 pandemic has exacerbated these challenges. Early detection and prompt treatment are essential to prevent/reverse malnutrition and effectively reduce mortality and complication rates. Obesity has been declared an epidemic in the U.S.

Reporting Diagnosis of Malnutrition

ICD-10 codes to report malnutrition levels fall in the range E40 – E46.

E40 – Nutritional edema with dyspigmentation of skin and hair (kwashiokar should rarely be used in the U.S.)
E42 – Severe protein-calorie malnutrition with signs of both kwashiorkor and marasmus
E41 – Nutritional atrophy; severe malnutrition otherwise stated; severe energy deficiency (Nutritional marasmus should rarely be used in the U.S.)
E43 – Unspecified severe protein-calorie malnutrition (nutritional edema without mention of dyspigmentation of skin and hair)
E44 – Moderate protein calorie malnutrition
E44.1 – Mild protein-caloriemalnutrition
E45 – Retarded development following protein calorie malnutrition
E46 – Unspecified protein calorie malnutrition
E64 – Sequelae of protein calorie malnutrition

• E40 refers to Kwashiorkor is severe malnutrition with nutritional edema and dyspigmentation of skin and hair. It is rare occurrence in the U.S.
• E41 is used to report nutritional marasmus, a form of malnutrition characterized by consumption of inadequate amounts of both protein and calories, leading to an energy deficit in the body. Common symptoms include dehydration, chronic diarrhea, and stomach shrinkage. This severe malnutrition type occurs in young children and infants.
• E42 is used to report severe protein-calorie malnutrition with signs of both kwashiorkor and marasmus. This is an intermediate form of severe malnutrition.
• E43 is unspecified severe malnutrition and used to report severe malnutrition or starvation edema.

E44.0 (moderate malnutrition), E44.1 (mild malnutrition), and E46 (malnutrition, unspecified) are categorized as complication/comorbid conditions (CCs).

Severe malnutrition diagnosis codes are for major complications/comorbid conditions (MCCs) and are scrutinized by commercial and government payers. When reporting a severe malnutrition ICD-10 code, documentation must support muscle wasting with clinical indicators to avoid a reduction in the assigned Diagnosis-Related Groups (DRGs) (ICD-10 Monitor).

To meet the American Society for Parenteral and Enteral Nutrition (ASPEN) criteria for severe malnutrition in an acute care setting, the Association of Clinical Documentation Integrity Specialists (ACDIS) reminds us that a patient must show the following symptoms:

• Energy intake: less than () 5 days
• Weight loss (% of body weight):
  • >2% in one week; or
  • >5% in one month; or
  • >7.5% in three months
• Muscle mass loss: moderate
• Body fat loss: moderate
• Edema masking weight loss: moderate to severe
• Reduced grip strength: measurably reduced

Document both Body Mass Index (BMI) and Weight Diagnosis

The Official Coding and Reporting Guidelines for ICD-10-CM state that clinicians other than the patient’s provider may document body mass index (BMI) (Z68.-). However, for reporting the BMI code, the provider must document both the BMI and the weight diagnosis.

Obesity categories are as follows:

• Underweight – BMI less than 18.5
• Normal – BMI is equal or greater than 18.5 and less than 25
• Overweight – BMI is equal or greater than 25 and less than 30
• Obesity, Class I – BMI is equal or greater than 30 and less than 35
• Obesity, Class II – BMI is equal or greater than 35 and less than 40
• Obesity, Class III (morbid or extreme obesity) – BMI is equal or greater than 40

Being underweight is coded as R63.6. Category Z68 includes codes for pediatric and adult BMI. BMI less than 20 or greater than 40 is classified as a complication/comorbid condition (CC) in the Medicare Severity Diagnosis Related Group (MS-DRG) methodology.

BMI Adult codes are used for persons 20 years of age or older.

Z68 Adult BMI

Z68.1 BMI less than 20

Z68.20 BMI 20.0-20.9

Z68.21 BMI 21.0-21.9

Z68.22 BMI 22.0-22.9

Z68.23 BMI 23.0-23.9

Z68.24 BMI 24.0-24.9

Z68.25 BMI 25.0-25.9

Z68.26 BMI 26.0-26.9

Z68.27 BMI 27.0-27.9

Z68.28 BMI 28.0-28.9

Z68.29 BMI 29.0-29.9

Z68.30 BMI 30.0-30.9

Z68.31 BMI 31.0-31.9

Z68.32 BMI 32.0-32.9

Z68.33 BMI 33.0-33.9

Z68.34 BMI 34.0-34.9

Z68.35 BMI 35.0-35.9

Z68.36 BMI 36.0-36.9

Z68.37 BMI 37.0-37.9

Z68.38 BMI 38.0-38.9

Z68.39 BMI 39.0-39.9

Z68.41 BMI 40.0-44.9

Z68.42 BMI 45.0-49.9

Z68.43 BMI 50.0-59.9

Z68.44 BMI 60.0-69.9

Z68.45 BMI 70 and over

For pediatric patients, BMI measurement is based on age, gender, and percentiles. BMI pediatric codes are used for persons between ages 2 and 19. ICD-10 codes Z68.51 – Z68.54 should be used to report pediatric BMI percentile as a non-primary diagnosis.

Pediatric BMI Percentile Range

Z68.51 BMI, less than 5th percentile for age
Z68.52 BMI, 5th percentile to less than 85th percentile for age
Z68.53 BMI, 85th percentile to less than 95th percentile for age
Z68.54 BMI, greater than or equal to 95th percentile for age

It is important to develop facility-specific guidelines for the documentation of BMI for code assignment. Things to consider when reporting BMI include:

• Did the provider document the patient’s weight?
• Does the associated diagnosis (such as overweight or obesity) meet the definition of a reportable diagnosis?
• At what point was the BMI captured – during the patient’s admission or discharge?
• Was weight addressed during the patient’s stay?

The diagnosis of obesity often triggers payer review of claims. That’s why medical coding companies need to ensure that where weight is coded, the clinical documentation and code support the condition and associated BMI.