ICD-10 Code K73.8: Other chronic hepatitis, not elsewhere classified

Key Takeaways

ICD-10 Code K73.8 identifies other chronic hepatitis, not elsewhere classified – a billable, specific code effective for FY2026 (October 1, 2025).

K73.8 carries five Excludes1 restrictions – chronic alcoholic hepatitis (K70.1-), chronic drug-induced hepatitis (K71.-), chronic reactive/granulomatous hepatitis (K75.2-K75.3), and chronic viral hepatitis (B15-B19) – none of which can be coded alongside it.

When autoimmune hepatitis is confirmed in documentation, K75.4 is the preferred code over K73.8 due to greater specificity.

Pabau’s claims management software runs pre-submission validation checks, catching missing claim details like membership numbers or authorization codes before a claim goes out.

ICD-10 Code K73.8 is a billable code for chronic hepatitis of six or more months’ duration once a viral or autoimmune cause has been ruled out and the presentation does not fit the K73.0-K73.2 patterns. Coders face a choice between several K73 subcategories, and defaulting to “unspecified” when the documentation supports something more precise triggers denials and audit flags.

This reference covers everything coders, billers, and clinicians need to assign claims management software-ready diagnoses accurately: billable status, excludes notes, the full K73 subcategory comparison, differential coding against B18.x viral hepatitis codes, documentation requirements, common errors, and the ICD-9-CM crosswalk.

ICD-10 Code K73.8: Billable status and code details

K73.8 is a billable, specific ICD-10-CM code. It can be used directly on a claim to indicate a diagnosis for reimbursement purposes – no additional subclassification is needed. The AAPC ICD-10-CM code reference and icd10data.com both confirm its billable status.

The 2026 edition of ICD-10-CM Code K73.8 became effective on October 1, 2025, as part of the standard CMS annual update cycle.

What does K73.8 mean? Clinical description

The qualifier “other” in K73.8 does specific work in ICD-10-CM. It signals that the condition is chronic hepatitis that does not fit any of the more precisely defined subcategories within K73 – and that a viral etiology (hepatitis B or C) has been ruled out or is not documented.

Clinically, K73.8 covers chronic liver inflammation of six or more months’ duration where documentation identifies hepatitis but cannot assign it to a named subtype. Conditions this code may cover include cryptogenic chronic hepatitis and seronegative or atypical autoimmune hepatitis, when confirmed autoimmune hepatitis (K75.4) does not apply.

Drug-induced chronic hepatitis is not one of these “other” presentations. It carries an Excludes1 note under K73 and must be coded under K71.- (toxic liver disease), never K73.8.

• Chronicity threshold: hepatic inflammation present for six or more months, confirmed by labs or biopsy
• Etiology status: viral causes (B18.x) excluded or not documented; named autoimmune hepatitis (K75.4) not confirmed
• Clinical evidence required: elevated transaminases, biopsy findings, or imaging consistent with chronic inflammation
• Not a residual code: K73.9 (“unspecified”) is appropriate when type is genuinely unknown; K73.8 requires documentation that the hepatitis is “other” in a clinically meaningful sense

K73.8 excludes notes: What this code does not cover

K73.8 carries five Excludes1 notes at the K73 category level, which means none of these conditions can be coded at the same encounter as K73.8 – they are mutually exclusive by definition. According to the CMS ICD-10 codes page, Excludes1 instructions indicate that the excluded code represents the same condition and should never be used with the parent code.

The practical consequence: if a patient’s chart confirms alcoholic etiology, drug- or toxin-induced etiology, a reactive or granulomatous histologic pattern, or a positive viral hepatitis result (hepatitis B surface antigen or hepatitis C RNA), you cannot use K73.8. The corresponding excluded code takes over completely.

Submitting K73.8 when one of these five excluded conditions applies is a claim accuracy violation and a common audit target. Drug-induced chronic hepatitis is a particularly frequent misclassification – it must be coded under K71.- (toxic liver disease), never K73.8.

K73.8 vs. related codes in the K73 category

The K73 category contains four subcodes. Choosing incorrectly among them is the most common error in chronic hepatitis coding. The distinction between K73.8 (other/NEC) and K73.9 (unspecified) trips up even experienced coders. This table, drawn from the CDC/NCHS ICD-10-CM web tool, maps the full category:

K73.8 vs. K73.9 – the critical distinction: K73.8 applies when the provider documents a specific characterization of the hepatitis (such as “cryptogenic chronic hepatitis” or “seronegative autoimmune hepatitis”) but that characterization does not match K73.0, K73.1, or K73.2 patterns precisely.

K73.9 applies when documentation simply says “chronic hepatitis” with no further detail. Using K73.9 when K73.8 is supportable in the record is an undercoding error.

When to use K73.8 vs. viral hepatitis codes (B18.x)

The single most consequential coding decision for chronic hepatitis is whether the etiology is viral. The B18.x series (chronic viral hepatitis) carries an Excludes1 instruction against K73.8, so the two groups are mutually exclusive by definition, the same way K71.2 is excluded for drug-induced etiology. Here is how the logic flows at the encounter level:

• Hepatitis B antigen confirmed (HBsAg positive): use B18.1 (without delta-agent) or B18.0 (with delta-agent). K73.8 is excluded.
• Hepatitis C RNA positive (HCV confirmed): use B18.2. K73.8 is excluded.
• Serology negative, clinical diagnosis of chronic hepatitis: K73.8 is appropriate when documentation specifies a type that does not fit K73.0-K73.2.
• Viral status untested or inconclusive: query the provider. Assigning K73.8 when viral testing is pending is premature and may require amendment later.
• Autoimmune hepatitis serologically confirmed (ANA/SMA positive, typical histology): K75.4 is preferred. K73.8 can apply to seronegative or atypical autoimmune presentations if the provider documents this distinctly.

The WHO ICD-10 browser makes this hierarchy clear: B18.x codes sit in the infectious disease chapter (B00-B99), completely separate from the digestive diseases chapter (K00-K93) where K73.8 lives. The underlying etiology determines the chapter, not the clinical presentation alone.

Documentation requirements for K73.8

Payers reviewing K73.8 claims look for documentation that justifies both the “chronic” qualifier and the “other” designation. Missing either element leaves the claim vulnerable to downcoding or denial.

That holds whether the workup started in a GP practice or a functional medicine practice running the metabolic panel – the provider note needs to carry all four elements listed below before coding.

• Chronicity: documentation explicitly states hepatitis duration of six or more months, or cites prior encounter records confirming ongoing inflammation. A single elevated ALT without duration context does not meet this threshold.
• Etiology exclusion: the note must document that viral hepatitis (B and C at minimum) has been ruled out through negative serologies, or provide a clinical rationale for why testing was not pursued.
• Histologic or laboratory evidence: biopsy findings, persistent transaminase elevation (ALT/AST), or imaging consistent with chronic hepatic inflammation strengthens the claim. Biopsy grading (Metavir, Ishak) gives the strongest support.
• Specificity of “other”: the provider should document what type of hepatitis this is (even descriptively) to distinguish K73.8 from K73.9. Phrases like “cryptogenic chronic hepatitis” or “seronegative autoimmune hepatitis” support K73.8 over K73.9; a note describing drug-induced chronic hepatitis instead supports K71.- (toxic liver disease), not K73.8.

Facilities using electronic client records can structure templates around these four elements so providers capture the necessary detail at the point of care. Chasing documentation post-encounter for HIPAA-compliant clinical documentation purposes is far more time-consuming than building it into the intake workflow.

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Common coding errors with ICD-10 Code K73.8

K73.8 has a narrow, specific use case. Most errors come from coders who treat it as a catch-all for any chronic hepatitis that does not immediately match a viral code. Understanding where coders go wrong reduces rework and audit exposure. The same specificity discipline applies to K74.60 and other liver diagnostic families.

• Using K73.8 when viral etiology is confirmed: the most frequent error. If HBsAg or HCV RNA is positive anywhere in the chart, K73.8 is excluded. Some coders assign it when the gastroenterology referral note does not repeat the serology results that appear in the primary care record.
• Coding drug-induced chronic hepatitis as K73.8: a persistent misclassification. Drug- or toxin-induced chronic hepatitis is Excludes1 from category K73 in its entirety and must be coded under K71.- (toxic liver disease), never K73.8, regardless of how the provider phrases the diagnosis.
• Defaulting to K73.8 when K73.9 is correct: when documentation genuinely does not specify the hepatitis type, K73.9 (unspecified) is the appropriate code. K73.8 requires that the provider has characterized the hepatitis as a specific “other” type – not that the type is simply unknown.
• Missing K75.4 for confirmed autoimmune hepatitis: when serologic markers (ANA, SMA, anti-LKM1) and histology confirm autoimmune hepatitis, K75.4 is the more specific code. Using K73.8 in this scenario is valid only for seronegative or atypical presentations where the provider explicitly documents this distinction.
• Coding K73.8 for NAFLD/NASH: non-alcoholic fatty liver disease (K76.0) and non-alcoholic steatohepatitis are not chronic hepatitis in the ICD-10 classification sense. These conditions have their own codes and do not map to K73.8.
• Omitting co-diagnosis codes: K73.8 rarely presents alone. Transaminitis (R74.01), hepatomegaly, and portal hypertension codes may all apply to the same encounter. Failing to code co-existing conditions leaves revenue and clinical documentation incomplete.

Good medical office compliance practices include a periodic audit of K73.8 claims against the chart to catch these patterns before they surface in external reviews.

K73.8 and co-occurring diagnoses: Transaminitis and liver enzyme elevation

Chronic hepatitis almost always presents with abnormal liver function tests. Elevated transaminases (AST and ALT) are so central to the diagnosis that coders frequently ask whether they should be coded separately or left implicit in K73.8.

According to the general coding principle in CMS ICD-10-CM Official Guidelines, signs and symptoms integral to a confirmed diagnosis are not coded separately. However, liver enzyme elevation significant enough to be monitored or investigated independently of the hepatitis diagnosis may warrant a separate code.

The relevant code is R74.01, which covers elevation of liver transaminase levels. When a provider separately notes and monitors transaminitis as a clinical problem distinct from the underlying hepatitis, R74.01 can be coded alongside K73.8 at the same encounter.

Sequencing follows standard guidelines: the condition driving the visit is the principal diagnosis. K73.8 leads if the hepatitis management is the reason for the encounter, while R74.01 leads only if the enzyme elevation investigation is the primary reason.

Verifying sequencing against current CMS Official Guidelines Section I.C.18 for signs and symptoms is advisable before finalizing claims that combine K73.8 with R74.01. Patient data security also depends on ensuring co-diagnosis documentation is accurate, not just complete – inaccurate coding creates liability beyond the immediate denial.

ICD-9-CM to ICD-10-CM crosswalk for K73.8

Legacy systems and long-term health record comparisons sometimes require mapping K73.8 back to its ICD-9-CM predecessor. The General Equivalence Mappings (GEMs) published by CMS provide the official crosswalk. Practices using EHR integration to bridge ICD-9 and ICD-10 data should reference these mappings rather than relying on memory.

The crosswalk confirms that K73.8 has a narrow ICD-9-CM source: 571.49. Do not use a GEM mapping as justification to upgrade a previously coded 571.40 (unspecified) to K73.8 without reviewing the underlying clinical record for supporting documentation.

Conclusion

K73.8 solves a specific coding problem: chronic hepatitis that has been worked up thoroughly but does not fit a viral or clearly histologic pattern. The code is valid and billable, but it demands precise documentation – confirmed chronicity, exclusion of viral etiology, and a provider characterization that distinguishes “other” from “unspecified.”

Pabau’s integrated billing and clinical documentation tools let you build those requirements directly into consultation templates, so the documentation that supports ICD-10 Code K73.8 is captured at the point of care rather than chased afterward. See how Pabau handles diagnosis-to-claim workflows by scheduling a demo with our team.

Continue your research

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