Cachexia ICD-10 coding has two answers, not one. R64 is the code for cachexia with no documented underlying cause. E88.A is the code when an underlying condition is documented, and it is the one most inpatient charts should be landing on.
Key takeaways
- R64, Cachexia, is billable and sits in Chapter 18 with the symptom codes.
- E88.A, Wasting disease (syndrome) due to underlying condition, is billable, carries a Code first note, and lists "cachexia due to underlying condition" as an inclusion term.
- The two carry a reciprocal Excludes1, so they are never reported together on one encounter.
- The Alphabetic Index routes every qualified sub-entry to E88.A. Only unqualified cachexia stays at R64.
- The most common error is coding R64 for a patient whose cancer, heart failure or COPD is documented in the same chart.
Cachexia ICD-10 codes at a glance
| Code | Descriptor | Billable | Assign when |
|---|---|---|---|
| R64 | Cachexia | Yes | Cachexia is documented and no underlying condition is identified as its cause |
| E88.A | Wasting disease (syndrome) due to underlying condition | Yes | Cachexia is attributed to a documented illness. Sequence that illness first |
| E41 | Nutritional marasmus | Yes | Severe protein-energy malnutrition of the marasmic type |
| R63.4 | Abnormal weight loss | Yes | Weight loss is documented but cachexia is not diagnosed |
| M62.84 | Sarcopenia | Yes | Age-related loss of muscle mass and strength |
| M62.5- | Muscle wasting and atrophy, not elsewhere classified | No | Localised wasting or disuse atrophy. Requires a further character for site |
The split that changed the answer
For most of the life of ICD-10-CM, cachexia was R64 and that was the whole question. No longer.
E88.A, Wasting disease (syndrome) due to underlying condition, was added effective 1 October 2023. Its inclusion term is literally "cachexia due to underlying condition", it carries a Code first underlying condition instruction, and it took the Alphabetic Index entries with it. The CMS tabular addenda errata for FY2024 shows the resulting index structure at the main term Cachexia:
Cachexia R64
- due to
- - malnutrition (see also Malnutrition, severe) E88.A
- - underlying condition E88.A
Read that literally. The unqualified main term still leads to R64; every qualified sub-entry leads to E88.A. If the documentation says what the cachexia is due to, the index has already answered the question.
The Excludes1 relationship
R64 and E88.A are never coded together on the same encounter. Both carry Excludes1 notes pointing at each other, and reporting the pair is a routine cause of denials.
R64 excludes abnormal weight loss (R63.4), cachexia due to underlying condition (E88.A) and nutritional marasmus (E41). E88.A excludes cachexia NOS (R64) and nutritional marasmus (E41), with an Excludes2 for failure to thrive (R62.51, R62.7).
The FY2026 Official Guidelines define the note without ambiguity: a type 1 Excludes note is a pure excludes note meaning NOT CODED HERE, and indicates the excluded code should never be used at the same time as the code above it. It is used where two conditions cannot occur together, which is exactly the position here. Cachexia either has a documented cause or it does not.
Documentation requirements
Three things in the record decide the code.
Is cachexia actually documented? Neither code is assignable from weight loss, a low BMI or a body composition report. If the provider documents weight loss without diagnosing cachexia, R63.4 is the honest code.
Is an underlying condition documented, and is the cachexia linked to it? ICD-10-CM does not presume a causal link. A chart carrying both "stage IV pancreatic adenocarcinoma" and "cachexia" with no linking language is a query opportunity, not an assumption.
Is it cachexia, or is it malnutrition? These coexist constantly and the index treats them separately. Where a dietitian has documented severe protein-energy malnutrition against recognised criteria, that diagnosis has its own code and its own reimbursement weight.
Sequencing
E88.A carries a Code first note, so the underlying condition is sequenced first and E88.A follows as a secondary code.
R64 has no code first note, because by definition nothing has been identified to sequence ahead of it. As a Chapter 18 symptom code it is acceptable for reporting when a related definitive diagnosis has not been established by the provider, which is exactly the situation it is now reserved for.
The four miscodes worth checking for
R64 on a chart with a documented cause. The most common error since October 2023. If the cancer, heart failure, COPD or CKD is documented and linked, the answer is E88.A.
M62.84 for a cachectic patient. Sarcopenia is age-related; cachexia is disease-driven systemic wasting. Substituting one for the other is inaccurate and audit-prone. See our sarcopenia ICD-10 guide.
M62.5- for systemic wasting. M62.5- is site-specific muscle wasting and atrophy not elsewhere classified: the family for disuse atrophy of a limb, not a whole-body catabolic syndrome.
Both cachexia codes on one encounter. The Excludes1 makes it invalid.
The pathway behind the code
Because E88.A is always secondary, the code that leads is the disease: most often cancer, chronic heart failure, COPD, chronic kidney disease or HIV. The clinical background sits in cachexia definition and cardiac cachexia, which explains why heart failure charts need dry weight before the 6% threshold means anything.
It also explains why E88.A landed in the metabolic chapter rather than a nutritional one. Cachexia is driven by signalling, not intake. Myostatin, or GDF-8, and the related ligand activin A act through the activin type IIB receptor to restrain muscle growth, and that axis has been the main drug target in wasting syndromes. Nothing has been approved, which is one reason the coding conversation stays on documentation. Our myostatin and cancer cachexia article covers the trial record.
Sources
- ICD-10-CM code R64, Cachexia, AAPC Codify.
- ICD-10-CM code E88.A, Wasting disease (syndrome) due to underlying condition, AAPC Codify.
- ICD-10-CM Tabular Addenda (FY24) Effective October 1, 2023, Errata, CMS.
- ICD-10-CM Official Guidelines for Coding and Reporting FY 2026, CMS.
Frequently asked questions
What is the ICD-10 code for cachexia?
R64 if no underlying cause is documented, E88.A if the cachexia is attributed to a documented condition, sequenced after that condition. Both are billable, and an Excludes1 note prevents them being reported together.
Is R64 still valid?
Yes. R64 remains valid for cachexia NOS. What changed in the FY2024 update is that it stopped being the default: once documentation attributes the cachexia to an underlying condition, the index routes to E88.A.
Can cachexia and malnutrition be coded together?
They are separate diagnoses with separate codes, so both may be reported when both are documented, subject to the Excludes notes. E88.A carries an Excludes1 for nutritional marasmus (E41), so those two cannot be reported together.
Can I assume the cancer caused the cachexia?
No. ICD-10-CM does not presume a causal relationship unless the classification says so or the provider documents the link. A chart listing a malignancy and cachexia separately, with no linking language, supports a query rather than an assumption.
Is cachexia a CC or MCC?
Severity designations are set by the MS-DRG grouper version in force for the discharge date and are revised annually, so verify against the current grouper rather than a published figure.
This article is for coding education only and is not medical advice or a substitute for the official code set. Always verify assignments against the current fiscal year ICD-10-CM Alphabetic Index, Tabular List and Official Guidelines, together with your organisation's coding policies and any applicable payer rules.