ICD-10 Code E52: Niacin deficiency (pellagra) coding reference

Key Takeaways

ICD-10 Code E52 is a billable ICD-10-CM diagnosis code for niacin deficiency (pellagra), classified under E50-E64 (Other nutritional deficiencies).

E52 applies to three official synonyms: niacin (-tryptophan) deficiency, nicotinamide deficiency, and pellagra (alcoholic).

A Type 1 Excludes note means E52 cannot be coded alongside the excluded condition in the same encounter.

Pabau’s claims management software helps practices document and submit nutritional deficiency diagnoses accurately, reducing claim errors.

ICD-10 Code E52 describes a disease caused by deficiency of niacin (Vitamin B3) or its metabolic precursor, tryptophan. Niacin is essential for cellular energy metabolism, and prolonged deficiency leads to a multisystem disorder historically known as pellagra. The condition is classically described by three clinical hallmarks: dermatitis, diarrhea, and dementia (the “three Ds”). A fourth D, death, can occur in severe, untreated cases.

E52 is a fully billable ICD-10-CM diagnosis code for the 2026 fiscal year. It requires no additional subcode and can be used as a principal or secondary diagnosis depending on the clinical encounter context. Confirmed across the AAPC Codify database and multiple coding references, its billable status is stable and not subject to current audit flags.

Code hierarchy and classification

• ICD-10-CM Chapter 4: Endocrine, nutritional and metabolic diseases (E00-E89)
• Block: Other nutritional deficiencies (E50-E64)
• Code: E52 Niacin deficiency [pellagra]
• Billable: Yes (valid for HIPAA-covered transactions)
• Effective date: October 1, 2015 (unchanged through FY2026)

The bracket notation “[pellagra]” in the code title is the ICD-10-CM convention for indicating a synonym. It does not create a separate subcategory. Both “niacin deficiency” and “pellagra” route to the same single-code E52.

Applicable synonyms for ICD-10 Code E52

The ICD-10-CM tabular list includes an “Applicable To” note under E52 that officially recognizes three synonym terms. Any of these diagnoses routes to E52 when documented in the medical record.

Isocitrate dehydrogenase deficiency also appears in some coding databases as a listed synonym. However, coders should note that isocitrate dehydrogenase (IDH) mutations are more commonly associated with oncologic contexts and may require separate clinical verification before applying E52 on that basis alone. When in doubt, query the treating clinician.

Alcoholic pellagra: Sequencing considerations

When the documented cause is alcohol-related niacin malabsorption, E52 is the correct diagnosis code. Coders should also evaluate whether an alcohol use disorder code from the F10.x category applies as a secondary or principal diagnosis, depending on the reason for the encounter. Pellagra (alcoholic) does not require a separate E52 subcode; the Applicable To note makes the routing explicit.

Excludes notes for ICD-10 Code E52

ICD-10 Code E52 carries a Type 1 Excludes note. Understanding the difference between Type 1 and Type 2 exclusions is essential before coding any nutritional deficiency encounter.

Type 1 Excludes: What it means in practice

A Type 1 Excludes note is a pure exclusion. It means the excluded condition and E52 are mutually exclusive at that code level: if the excluded condition is present, E52 cannot be assigned in the same coding encounter for the same condition. This differs from Type 2 Excludes, which simply signals that a code is classified elsewhere but may still be reported together.

The specific codes excluded under E52’s Type 1 note should be confirmed against the current CMS ICD-10-CM tabular list for FY2026, as excludes notes are updated annually. Coders working in nutritional deficiency documentation can verify current exclusions via the ICD List free lookup or the official CDC/NCHS coding tool.

Adjacent and related codes to ICD-10 Code E52

Selecting E52 correctly requires knowing what the surrounding codes cover. Confusion between E52 and its neighbors in the E50-E64 block is a frequent source of coding errors, particularly for B-vitamin deficiencies that share overlapping clinical presentations.

The most clinically important distinction is between E52 and E51.2 (Wernicke’s encephalopathy). Both can present with neurological symptoms in malnourished or alcohol-dependent patients, but they reflect entirely different deficiencies.

Wernicke’s encephalopathy is thiamine-specific; pellagra dementia is niacin-specific. Assign based on the documented deficiency, not on symptoms alone. Practices handling complex ICD-10 diagnostic code crosswalks for neurological and metabolic conditions understand how much precision this differentiation requires.

When to use E53.x instead of E52

Use E53.x only when niacin (Vitamin B3) deficiency has not been confirmed and the deficient B vitamin is something other than niacin. If laboratory findings or clinical documentation confirm niacin deficiency specifically, E52 is the correct code.

E53.9 (Vitamin B deficiency, unspecified) should never be used when a specific B vitamin can be identified. Coders working with nutritional and mental health diagnostic codes regularly encounter this precision requirement across the E50-E64 block.

Accurate diagnostic coding starts with accurate documentation

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Clinical documentation requirements for ICD-10 Code E52

E52 is not a code assigned based on symptoms alone. Payers expect documentation that supports a confirmed deficiency diagnosis, not just the presence of dermatitis or diarrhea. The documentation requirements below reflect ICD-10-CM Official Guidelines for Coding and Reporting standards and standard payer medical necessity expectations.

Documentation elements that support E52

• Confirmed niacin deficiency: The clinician’s documentation must state “niacin deficiency,” “pellagra,” “nicotinamide deficiency,” or “niacin-tryptophan deficiency” explicitly. Symptom-based coding alone (e.g., coding from the dermatitis or the diarrhea) is incorrect.
• Laboratory context: Plasma niacin or nicotinamide levels, urinary N-methylnicotinamide, or tryptophan metabolite panels support the diagnosis. Labs are not mandatory for coding but strengthen medical necessity and audit defense.
• Dietary or malabsorptive history: Documentation of restrictive diets, malabsorption syndromes, alcohol use disorder, or food insecurity explains the mechanism and reinforces clinical plausibility.
• Treatment plan alignment: Prescribed niacin supplementation or dietary intervention should be reflected in the treatment plan and match the coded diagnosis.
• Principal vs. secondary sequencing: If the patient presents primarily for pellagra management, E52 is principal. If another condition drives the encounter and pellagra is a concurrent finding, E52 sequences as secondary.

Practices using structured digital intake forms and templated clinical notes see fewer documentation gaps at the time of claim submission. When intake workflows capture dietary history, supplement use, and prior lab results systematically, coders have the specificity they need to assign E52 confidently. For nutritional and integrative medicine practices specifically, functional medicine software with structured note templates reduces the “query the clinician” cycle.

Lab findings that support E52 documentation

While labs are not required for code assignment, the following findings commonly appear in records supporting an E52 diagnosis and may be requested by payers during audits.

• Low plasma niacin or nicotinamide concentrations
• Reduced urinary N-methylnicotinamide excretion (a direct niacin metabolite measure)
• Low serum tryptophan levels (when tryptophan-pathway deficiency is suspected)
• Evidence of malabsorption: low albumin, abnormal B12/folate, elevated homocysteine in the same panel

Practices that manage IV therapy or nutritional infusion services benefit from thorough pre-treatment documentation. Reviewing IV therapy intake documentation frameworks shows how structured intake captures the nutritional baseline that later supports diagnostic coding accuracy. For IV therapy EMR software users, linking lab panels to clinical encounters within the same record reduces the manual documentation burden at coding time.

DRG grouping and payer context for ICD-10 Code E52

ICD-10 Code E52 is grouped within MS-DRG v43.0 according to data from icd10data.com, though coders should verify the current grouper assignment against CMS MS-DRG documentation for the applicable fiscal year. DRG grouping affects hospital reimbursement directly; outpatient and professional fee claims are not DRG-based but are still subject to medical necessity review under the assigned diagnosis.

Payer-specific coding considerations

Nutritional deficiency codes in the E50-E64 block are low-frequency diagnoses for most practices, which means payers may flag unusual utilization patterns. A practice submitting multiple E52 claims across a short period without supporting documentation is at higher audit risk than practices where the diagnosis appears rarely and with complete documentation.

For alcohol-related pellagra specifically: F10.x (alcohol use disorder) codes may need to be sequenced alongside E52. The sequencing order depends on which condition is the focus of the encounter. Clinicians working in IV therapy clinic best practices that include nutritional repletion protocols encounter this dual-coding scenario frequently. Documenting both the deficiency and its underlying cause reduces audit vulnerability and supports comprehensive care records.

The WHO ICD-10 browser and CMS tabular resources are the authoritative references for verifying E52 classification, excludes notes, and any mid-year corrections. Coding references from commercial databases should be cross-checked against these primary sources annually, particularly after October 1 effective dates when new code sets take effect.

Patient record integrity and E52

Every E52 encounter should produce a complete patient records documentation trail: the clinical note documenting the deficiency, any supporting labs ordered or reviewed, the treatment plan, and the coded claim. When those elements align, payer challenges are substantially easier to resolve. Practices that manage medical forms at their practice systematically report fewer documentation-to-claim discrepancies during audits.

Conclusion

ICD-10 Code E52 is a precise, billable code for a condition that carries real clinical consequences when underdocumented or miscoded. Using E53.9 when niacin deficiency is confirmed, or failing to sequence alcohol use disorder alongside alcoholic pellagra, are the two errors most likely to generate denials or audit flags on E52 claims.

Pabau’s practice management platform supports clean E52 documentation with structured clinical note templates, integrated lab result tracking, and streamlined claim submission. If your practice manages nutritional deficiency diagnoses regularly, see how Pabau handles the documentation-to-claim workflow: explore our claims management software or book a demo today.

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