E46 vs R63.6
E46 and R63.6 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on R63.6
malnutrition (E40-E46)
E46
Unspecified protein-calorie malnutrition
BillableUnspecified
- Chapter 4
- Endocrine, nutritional and metabolic diseases
- Section
- E40-E46
Use when the record says
- Malnutrition NOS
- Protein-calorie imbalance NOS
Indexed under
- Calorie deficiency or malnutrition
- Malnutrition
- Cataract › malnutrition-dehydration (cortical) (immature) (incipient)
- Deficiency, deficient › protein
- Malnutrition › protein
R63.6
Underweight
Billable
- Chapter 18
- Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
- Section
- R50-R69
Indexed under
- Underweight
These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027