ICD-10 Code for Elevated ALT: Complete Coding Guide for Providers

• The primary ICD-10-CM code for an elevated ALT finding is R74.01, classified under "Abnormal findings on examination of blood" and specifically designated for elevated liver enzymes.
• When a definitive diagnosis such as hepatitis, cirrhosis, or fatty liver disease has been confirmed, that diagnosis code should be used as the primary code rather than R74.01.
• Proper documentation of the degree of ALT elevation, clinical context, and associated findings is essential for accurate billing and coding compliance.
• The code R74.01 became effective October 1, 2016, splitting from the broader R74.0 category to provide greater specificity for elevated liver enzyme documentation.
• Understanding coding conventions for elevated ALT ensures appropriate reimbursement and supports accurate epidemiological tracking of liver disease.

This coding guide was developed through a systematic review of the following authoritative sources:

• CDC ICD-10-CM Official Guidelines for Coding and Reporting (FY 2025 edition) for code selection rules and sequencing conventions.
• CMS Medicare Claims Processing Manual for billing requirements and documentation standards related to laboratory diagnostic coding.
• AASLD (American Association for the Study of Liver Diseases) clinical practice guidance for the evaluation of abnormal liver chemistries.
• AMA CPT Professional Edition for procedural code pairings with ICD-10 diagnostic codes.
• All ICD-10-CM codes referenced were verified against the official CDC code tables current as of April 2026.

Alanine aminotransferase (ALT) is an enzyme found predominantly in the cytoplasm of hepatocytes. When liver cells are damaged or inflamed, ALT leaks into the bloodstream, causing serum levels to rise. Because of its high specificity for hepatic injury, ALT is one of the most commonly ordered liver function tests (LFTs) in clinical practice.

Normal ALT values typically range from 7 to 56 units per liter (U/L), though reference ranges vary slightly between laboratories. Elevated ALT levels signal hepatocellular damage and can result from a wide spectrum of conditions, ranging from benign and transient causes such as strenuous exercise to serious diseases including viral hepatitis, alcoholic liver disease, nonalcoholic fatty liver disease (NAFLD), drug-induced liver injury, and autoimmune hepatitis.

The clinical significance of an elevated ALT result depends on multiple factors: the degree of elevation, the rate of change, the patient's age and sex, comorbid conditions, medications, and alcohol use patterns. A mild elevation (less than 2 times the upper limit of normal) may be transient and clinically insignificant, while levels exceeding 10 times the upper limit of normal typically indicate acute hepatocellular injury requiring urgent evaluation.

Code Structure and Classification

The ICD-10-CM code R74.01 is defined as "Elevated liver enzymes." It falls within the following hierarchy:

• Chapter 18: Symptoms, signs, and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)
• Block: Abnormal findings on examination of blood, without diagnosis (R70-R79)
• Category R74: Abnormal levels of liver enzymes
• Subcategory R74.0: Nonspecific elevation of levels of transaminases and lactic acid dehydrogenase (LDH)
• Code R74.01: Elevated liver enzymes

This code was introduced in the FY2017 ICD-10-CM update to provide more granular specificity than the previous general code R74.0. The creation of R74.01 reflects the high prevalence of elevated liver enzyme findings in clinical practice and the need for precise diagnostic tracking.

When to Use R74.01

R74.01 should be used as a diagnosis code in the following clinical scenarios:

1. Initial presentation of an abnormal ALT result before a definitive diagnosis has been established.
2. Screening or surveillance laboratory findings where ALT elevation is detected incidentally.
3. Transient elevations that do not meet criteria for a specific liver disease diagnosis.
4. Elevated ALT with a normal workup where no underlying cause is identified after appropriate evaluation.

When NOT to Use R74.01

R74.01 should not be used as the primary diagnosis when a definitive liver condition has been established. In such cases, the specific condition should be coded as the primary diagnosis. Examples include:

According to ICD-10-CM Official Guidelines, Section II, Chapter 18: "Signs and symptoms codes (R00-R99) are to be used only when a definitive diagnosis has not been established." Once a provider has confirmed a specific liver disease, that condition should be sequenced as the primary diagnosis, and R74.01 may be listed as a secondary code if the elevated ALT finding is still clinically relevant.

Beyond R74.01, several related codes may be applicable depending on the clinical context and the specific laboratory findings:

R74 Series Codes

Codes for Specific Liver Enzyme Findings

When the elevation involves additional liver enzymes alongside ALT, consider these codes:

• R74.01 remains appropriate when both ALT and AST are elevated, as "elevated liver enzymes" encompasses multiple transaminase elevations.
• E88.01 (Alpha-1 antitrypsin deficiency) should be used when elevated ALT is attributable to this genetic condition.
• R93.2 (Abnormal findings on diagnostic imaging of liver and biliary tract) may accompany R74.01 when imaging abnormalities are also present.

Essential Documentation Elements

To support the use of ICD-10 code R74.01 and ensure claim acceptance, the medical record should include:

1. The specific ALT value and the laboratory reference range for context.
2. The clinical setting in which the test was ordered (routine screening, symptom evaluation, medication monitoring).
3. Associated symptoms, if any (fatigue, jaundice, right upper quadrant pain, nausea).
4. Relevant history including alcohol use, medication list, herbal supplements, and occupational exposures.
5. The degree of elevation categorized as mild (less than 2x ULN), moderate (2-5x ULN), or severe (greater than 5x ULN).
6. Plan for follow-up, including any additional diagnostic tests ordered.

Medical Necessity for Repeat Testing

Payers may require documentation of medical necessity for serial ALT monitoring. Acceptable reasons include:

• Monitoring response to hepatotoxic medications (statins, isoniazid, methotrexate).
• Surveillance of known chronic liver disease.
• Follow-up of a previously elevated ALT result.
• Pre-operative or pre-procedural assessment in patients with risk factors.

When billing for the laboratory test itself, the following CPT codes are commonly paired with ICD-10 R74.01:

The hepatic function panel (80076) is the most common way ALT is ordered in clinical practice, as it includes ALT, AST, alkaline phosphatase, total bilirubin, albumin, and total protein, providing a comprehensive assessment of liver function.

Scenario 1: Incidental Finding on Routine Labs

A 45-year-old male presents for an annual physical. A hepatic function panel reveals ALT of 78 U/L (reference: 7-56 U/L). No symptoms. No history of liver disease.

Primary Diagnosis: R74.01 (Elevated liver enzymes) Rationale: No definitive diagnosis has been established; the elevated ALT is an incidental finding.

Scenario 2: Elevated ALT in a Patient on Statin Therapy

A 62-year-old female on atorvastatin for hyperlipidemia has an ALT of 95 U/L on routine monitoring labs. She is asymptomatic.

Primary Diagnosis: R74.01 (Elevated liver enzymes) Secondary Diagnosis: E78.5 (Hyperlipidemia, unspecified) Rationale: The ALT elevation may be medication-related but is not yet confirmed as drug-induced liver injury.

Scenario 3: Elevated ALT Leading to NAFLD Diagnosis

A 52-year-old male with obesity and type 2 diabetes has persistently elevated ALT. After imaging and workup, NAFLD is diagnosed.

Primary Diagnosis: K75.81 (Nonalcoholic fatty liver disease) Secondary Diagnosis: R74.01 (Elevated liver enzymes) — optional Rationale: Once NAFLD is confirmed as the definitive diagnosis, it supersedes the symptom code.

Scenario 4: Acute Viral Hepatitis

A 28-year-old presents with jaundice, fatigue, and ALT of 2,400 U/L. Hepatitis A IgM is positive.

Primary Diagnosis: B15.9 (Acute hepatitis A without hepatic coma) Rationale: The definitive diagnosis of acute hepatitis A is established; R74.01 is not appropriate as the primary code.

Error 1: Using R74.0 Instead of R74.01

The code R74.0 (Nonspecific elevation of transaminase and LDH levels) is a three-character category code. Since the more specific code R74.01 exists, it must be used. Using R74.0 may result in claim denial or request for additional information.

Error 2: Coding Elevated ALT as the Primary Diagnosis When a Definitive Condition Exists

When a patient has established cirrhosis, hepatitis, or another specific liver disease, that diagnosis should be coded as the primary condition. Using R74.01 as the primary code in this context understates the severity of the patient's condition and may result in inappropriate reimbursement.

Error 3: Failing to Document the Reason for Testing

Without documentation of why the ALT test was ordered (symptoms, monitoring, screening), payers may question medical necessity. Always ensure the encounter note clearly states the indication for the laboratory test.

Error 4: Not Updating Codes When Diagnosis Changes

If a patient initially coded with R74.01 is subsequently diagnosed with a specific liver condition, the diagnosis code should be updated on future claims to reflect the confirmed diagnosis.

payer-Specific Requirements

Different payers may have varying requirements for covering serial ALT testing:

• Medicare: Covers ALT testing when medically necessary for diagnosis or monitoring of a documented condition. LCD (Local Coverage Determinations) may specify documentation requirements.
• Commercial insurers: May require prior authorization for repeat testing within certain timeframes.
• Medicaid: Requirements vary by state; some states limit the frequency of hepatic function panel testing.

Frequency Limitations

Many payers limit the frequency of hepatic function panel testing (CPT 80076) to:

• Once per year for routine screening.
• Every 3-6 months for medication monitoring.
• More frequent testing with documented acute conditions.

Exceeding these limits without supporting documentation may result in claim denial.

Accurate use of ICD-10 codes for elevated ALT has implications beyond individual patient billing. Public health agencies, including the CDC and WHO, use ICD-10 coded data to:

• Track the prevalence and incidence of liver disease at population levels.
• Identify geographic clusters of hepatotoxic exposures.
• Monitor the impact of public health interventions such as hepatitis vaccination programs.
• Allocate healthcare resources based on disease burden.

The specificity of R74.01 enables more precise epidemiological data compared to the broader R74.0 category, supporting better public health decision-making.

What is the correct ICD-10 code for an elevated ALT level?

The correct ICD-10-CM code is R74.01 (Elevated liver enzymes). This code applies when ALT is elevated above the laboratory reference range and no definitive diagnosis explaining the elevation has been established. If a specific liver disease has been diagnosed, that condition code should be used as the primary diagnosis instead.

Can R74.01 be used as a primary diagnosis?

Yes. According to ICD-10-CM guidelines, R74.01 can be used as a primary diagnosis when an elevated ALT is identified and no definitive underlying condition has been confirmed. However, once a specific diagnosis (such as hepatitis, cirrhosis, or NAFLD) is established, that diagnosis should be sequenced as the primary code, with R74.01 used secondarily if appropriate.

What is the difference between R74.0 and R74.01?

R74.0 is a three-character category code meaning "Nonspecific elevation of transaminase and lactic acid dehydrogenase (LDH) levels." R74.01 is a more specific code within that category, meaning "Elevated liver enzymes." Whenever possible, coders should use the most specific code available, which in this case is R74.01. Using R74.0 when R74.01 is applicable may be considered incomplete coding.

What ICD-10 code should I use for elevated ALT due to medications?

If elevated ALT is suspected to be caused by a medication but drug-induced liver injury has not been formally diagnosed, use R74.01 as the diagnosis code. If drug-induced liver injury is confirmed, use K71.x (Toxic liver disease) as the primary code, selecting the appropriate subcode based on the type of injury (e.g., K71.10 for toxic liver disease with hepatic necrosis without coma).

How should elevated ALT be coded in pregnancy?

For pregnant patients with elevated ALT, use R74.02 (Abnormal level of liver enzymes in pregnancy) as the primary code if no specific pregnancy-related liver condition (such as preeclampsia, HELLP syndrome, or intrahepatic cholestasis of pregnancy) has been diagnosed. If a specific condition is identified, code that condition as primary (e.g., O14.2 for HELLP syndrome).

Does insurance cover repeat ALT testing with R74.01?

Most insurers will cover repeat ALT testing billed with R74.01 when there is documented medical necessity, such as monitoring a previously elevated result, surveillance of a patient on hepatotoxic medications, or follow-up of an acute condition. However, payers may impose frequency limitations and require supporting documentation in the medical record.

Accurate ICD-10-CM coding for elevated ALT requires understanding the distinction between a laboratory finding (R74.01) and a definitive diagnosis. The code R74.01 is the appropriate choice when ALT elevation is identified without a confirmed underlying cause. However, clinical judgment and thorough documentation are essential: once a specific liver disease is diagnosed, that condition should be coded as the primary diagnosis.

For healthcare providers, the key principles are straightforward: use the most specific code available, document the clinical context thoroughly, update codes as the diagnostic picture evolves, and ensure that the reason for testing is clearly stated in every encounter note. For medical coders, understanding the hierarchy of R74 codes and the guidelines on symptom versus definitive diagnosis coding is critical for compliance and appropriate reimbursement.

By following these coding conventions, providers ensure accurate clinical documentation, support appropriate reimbursement, and contribute to the broader public health infrastructure that relies on ICD-10 coded data for liver disease surveillance and resource allocation.

This guide reflects ICD-10-CM codes current as of April 2026. Code updates occur annually on October 1st; always verify codes against the most current version of the ICD-10-CM code tables.