R74.01: Elevation of levels of liver transaminase levels

The ICD-10-CM code for elevated liver enzymes when a laboratory report documents an ALT or AST above the reference range and no underlying diagnosis has yet been established to explain the finding.

Billable

FY2027

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At a glance

Code Family

R74: Abnormal serum enzyme levels, within block R70–R79, abnormal findings on examination of blood without diagnosis.

HCC Mapping (v28)

None: R74.01 does not map to any CMS-HCC v28 category.

Condition

Elevated liver enzymes

Family Specificity

R74.01 is the transaminase-specific member of category R74. R74.02 covers lactic acid dehydrogenase, R74.8 covers abnormal levels of other serum enzymes, and R74.9 is the residual for an abnormal serum enzyme level that is not specified.

Billable

Yes: R74.01 is a valid billable code in the FY2026 code set and unchanged in the FY2027 update.

Which R74 code do I assign?

Category R74 groups abnormal serum enzyme findings, and the choice within it turns on which enzyme the laboratory report names. Before selecting any R74 code, confirm that no underlying diagnosis has been established to explain the elevation. If one has, that condition is coded instead.

When documentation says…

Code

Lab report shows elevated ALT or AST, cause not yet established

R74.01

Use when the record documents elevated liver transaminase values and no underlying condition accounting for them has been confirmed at the time of the encounter.

Lab report shows elevated lactic acid dehydrogenase

R74.02

Use when the elevated enzyme is LDH rather than a transaminase. The two are coded separately and R74.01 does not cover LDH.

Lab report shows a different serum enzyme elevated

R74.8

Use for abnormal levels of other serum enzymes. It is not assigned for a transaminase elevation, which belongs at R74.01.

Serum enzyme levels are abnormal but not otherwise specified

R74.9

Abnormal serum enzyme level, unspecified. Do not use it when the record names the enzyme, which is coded to R74.01, R74.02 or R74.8.

Tabular notes

EXCLUDES1

R74.01, subcategory R74.0 and category R74 carry no Excludes1 note in the FY2027 tabular.

EXCLUDES2

R74.01 carries no Excludes2 note of its own. Block R70-R79 carries an Excludes2 note for abnormal findings on antenatal screening of mother (O28.-), abnormalities of lipids (E78.-), abnormalities of platelets and thrombocytes (D69.-), abnormalities of white blood cells classified elsewhere (D70-D72), coagulation hemorrhagic disorders (D65-D68), diagnostic abnormal findings classified elsewhere and hemorrhagic and hematological disorders of newborn (P50-P61). Chapter 18 carries an Excludes2 note for abnormal findings on antenatal screening of mother (O28.-), certain conditions originating in the perinatal period (P04-P96), signs and symptoms classified in the body system chapters and signs and symptoms of breast (N63, N64.5).

USE ADDITIONAL AND CODE FIRST

R74.01 carries no use additional or code first instruction. ICD-10-CM guidelines nonetheless direct coders to sequence the underlying condition as primary once the cause of the elevated transaminases has been established.

SIGNS AND SYMPTOMS SEQUENCING

Guidelines Section I.C.18.b states that codes in the signs and symptoms chapter should be assigned in conjunction with a related definitive diagnosis when the sign or symptom is not routinely associated with that diagnosis. If the transaminase elevation is a known manifestation of a documented liver disease, R74.01 is not separately reported.

FY2027: NO CHANGES

The FY2027 codes addenda make no addition, deletion or revision in category R74. The FY2027 tabular addenda change no instructional note in it. R74.01 is in the FY2027 billable code list and is unchanged in the FY2027 update, effective 1 October 2026.

Operational & financial impact

Why specificity matters beyond the chart: risk adjustment, DRG assignment and denial exposure all follow from which code is selected.

CMS-HCC v28 (PY2024+)

No HCC mapping applies. R74.01 does not map to any Hierarchical Condition Category in CMS-HCC Model Version 28, which is fully operative at 100 percent weight for Medicare Advantage payment year 2026. Abnormal laboratory findings without a confirmed underlying diagnosis carry no HCC risk adjustment weight under the current CMS model.

WHEN THE UNDERLYING DIAGNOSIS IS ESTABLISHED

Once an underlying diagnosis such as hepatic steatosis or viral hepatitis is confirmed, that condition is coded, and it may or may not carry its own HCC designation. Leaving an established diagnosis coded as R74.01 forfeits any risk adjustment the confirmed condition would carry.

MEDICARE AND PAYER COVERAGE

There is no National Coverage Determination specific to R74.01. The code is used to support medical necessity for liver function panel testing or hepatology evaluation.

OUTPATIENT VERSUS INPATIENT

In the outpatient setting, R74.01 is coded only when the clinician has documented the elevated transaminases as a condition addressed or evaluated during the encounter. Abnormal labs found incidentally in the report are not coded without that documentation. For inpatients, UHDDS principal diagnosis rules apply, and if the workup identifies a definitive diagnosis before discharge, that diagnosis is coded rather than R74.01.

Documentation checklist to support R74.01

Chart elements that support code selection and reduce specificity-driven denials.

A laboratory report documenting elevated liver transaminase values, with ALT and/or AST above the reference range.

No confirmed underlying diagnosis accounting for the elevation at the time of the encounter.

Physician acknowledgment or ordering of the lab result in the clinical record.

Documentation that the elevated transaminases were addressed or evaluated during the encounter, rather than appearing only as an incidental result in the lab report.

A note to replace R74.01 with the confirmed diagnosis code once the underlying etiology is identified at a subsequent encounter.

FAQ

Can R74.01 be reported alongside a documented liver disease?

R74.01 is not reported alongside a documented liver disease when the elevation is a routine manifestation of that disease. Guidelines Section I.C.18.b allows a signs and symptoms code alongside a definitive diagnosis only when the sign is not routinely associated with it. An ALT or AST elevation expected in a documented hepatic condition is not separately reported. The underlying disease is coded instead.

What is the difference between R74.01 and R74.8?

R74.01 is specific to elevated liver transaminases, meaning ALT and AST. R74.8 covers abnormal levels of other serum enzymes. R74.8 is not assigned for a transaminase elevation. The residual R74.9 is not used when R74.01 or R74.02 is the correct, more specific code.

Can R74.01 be the principal or primary diagnosis?

Yes. R74.01 can be the principal or first-listed diagnosis when the elevated transaminase is the reason for the encounter and no underlying cause has been established. When the elevation is incidental to another condition that is the focus of the encounter, that condition is sequenced first and R74.01 is reported as an additional code only if it adds clinical significance.

Related codes

Codes in the same family as R74.01. Only codes with a published page render as links.

Sibling codes in the R74 family

R74.02: Elevation of levels of lactic acid dehydrogenase [LDH].
R74.8: Abnormal levels of other serum enzymes.
R74.9: Abnormal serum enzyme level, unspecified.

Additional codes to consider

Codes outside the R74 family considered alongside R74.01.

Consider instead

K76.0: Fatty (change of) liver, not elsewhere classified, when the provider documents fatty liver as the cause.
K70.10: Alcoholic hepatitis without ascites.
B18.2: Chronic viral hepatitis C, when the provider documents it as the cause.
K71.10: Toxic liver disease with hepatic necrosis, without coma, when the provider documents drug-induced liver disease with necrosis. Category K71 carries a Use additional note for the T36-T50 adverse effect code.
R79.89: Other specified abnormal findings of blood chemistry. The Index sends Elevated, liver function, test with no further detail here.

Sources

All claims on this page derive from government and professional-standards sources.

National Center for Health Statistics. (2026). International classification of diseases, tenth revision, clinical modification (ICD-10-CM) FY2027 files. https://www.cdc.gov/nchs/icd/icd-10-cm/files.html
Centers for Medicare & Medicaid Services and National Center for Health Statistics. (2026). ICD-10-CM official guidelines for coding and reporting FY2027. https://ftp.cdc.gov/pub/Health_Statistics/NCHS/Publications/ICD10CM/2027/ICD-10-CM-October-1-2026-FY27-Guidelines.pdf
Centers for Medicare & Medicaid Services. (2025). 2026 model software/ICD-10 mappings. https://www.cms.gov/medicare/payment/medicare-advantage-rates-statistics/risk-adjustment/2026-model-software-icd-10-mappings
Centers for Medicare & Medicaid Services. (2026). MS-DRG classifications and software, version 44. https://www.cms.gov/medicare/payment/prospective-payment-systems/acute-inpatient-pps/ms-drg-classifications-and-software