Understanding the Nuances of Coding Malnutrition

March is National Nutrition Month.

In honor of National Nutrition Month (March), here is a review of weight-related diagnoses. The Official Coding and Reporting Guidelines for ICD-10-CM state that other clinicians may document body mass index (BMI), but the provider must document the weight diagnosis. The BMI codes are found in category Z68, which includes codes for pediatric and adult BMI.

There are four levels to obesity, including the following:


ICD-10-CM Code

BMI Range



25.0 – 29.9

Low-risk Class 1

Category E66

30.0 – 34.9

Moderate-risk Class 2

Category E66

35.0 – 39.9

High-risk Class 3


>= 40

Note that ICD-10-CM does not contain specific codes for Class 1 and Class 2 obesity.

Malnutrition levels are covered in the range E40 – E46. Kwashiorkor is severe malnutrition with nutritional edema and dyspigmentation of skin and hair. This condition rarely occurs in the U.S., but has been a focus of the U.S. Department of Health and Human Services (HHS) Office of Inspector General (OIG). It is assigned E40. E41 is nutritional marasmus, which is a type of severe malnutrition that occurs in young children and infants. The symptoms are dehydration, chronic diarrhea, and stomach shrinkage. E42 is marasmic kwashiorkor, which is an intermediate form of severe malnutrition and has signs of kwashiorkor and marasmus. E43 is unspecified severe malnutrition. Payers often look for documentation of muscle wasting or cachexia when this diagnosis is assigned. The severe malnutrition codes are for major complications/comorbid conditions (MCCs), which is why they draw the attention of the payers and governmental agencies. The documentation of this condition must be strongly supported with clinical indicators to avoid a reduction in the assigned Diagnosis-Related Groups (DRGs). This is especially true if severe malnutrition is the only MCC/CC for the case.

The diagnosis codes of E44.0 (moderate malnutrition), E44.1 (mild malnutrition), and E46 (malnutrition, unspecified) complete the section of malnutrition. These malnutrition codes are classified as CCs.

There is also a code for being underweight (R63.6). The diagnosis codes for failure to thrive are divided into P92.6 for newborn, R62.51 for a child over 28-days, and R62.7 for adults.  

It is important that your facility-specific coding guidelines address the documentation of BMI for code assignment. When determining the guideline, consider at what point in the patient’s stay the BMI should be captured. Admission? Discharge? Many electronic health records automatically calculate BMI, but this diagnosis code cannot be reported unless the provider documents the weight diagnosis.

Programming Note: Listen to Laurie Johnson every Tuesday for her coding report on Talk Ten Tuesdays, 10 a.m. Eastern.



2021 ICD-10-CM Manual 

2021 Official Coding and Reporting Guidelines for ICD-10-CM



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