R74.01 — Elevation of liver transaminase levels

Clinical Definition

R74.01 identifies elevation of liver transaminase levels, commonly referred to as transaminitis. The liver transaminases—alanine aminotransferase (ALT) and aspartate aminotransferase (AST)—are intracellular enzymes released into the bloodstream when hepatocytes are damaged or destroyed. ALT is highly specific to the liver, while AST is also found in cardiac muscle, skeletal muscle, kidneys, and red blood cells. Normal reference ranges are generally 7-56 U/L for ALT and 10-40 U/L for AST, though values may vary by laboratory and patient demographics.

Elevated transaminases are among the most frequently encountered abnormal laboratory findings in clinical practice, affecting an estimated 8-10% of the U.S. population. The degree of elevation provides important diagnostic clues: mild elevations (less than 5 times the upper limit of normal) are seen in chronic hepatitis, nonalcoholic fatty liver disease (NAFLD), and medication effects; moderate elevations (5-15 times normal) suggest acute viral hepatitis or drug-induced liver injury; and marked elevations exceeding 15 times normal raise concern for ischemic hepatitis, acetaminophen toxicity, or acute viral hepatitis.

This code is classified as a sign or symptom code and should be used when the elevated transaminase finding is documented but no definitive underlying diagnosis has been established. Once a specific etiology is identified—such as nonalcoholic steatohepatitis, viral hepatitis, or alcoholic liver disease—the code for the confirmed diagnosis should be used as the primary code, with R74.01 assigned as an additional code only if the transaminase elevation itself warrants independent clinical attention or management.

When to Use R74.01

• ✓When laboratory results show elevated AST (aspartate aminotransferase) and/or ALT (alanine aminotransferase) levels above the reference range and a definitive underlying etiology has not yet been determined.
• ✓During the diagnostic workup phase for unexplained liver enzyme elevations, including ordering additional tests such as viral hepatitis panels, autoimmune markers, or imaging studies.
• ✓As a secondary code when the transaminase elevation requires independent monitoring or management beyond the treatment of a confirmed underlying liver condition.
• ✓When documenting abnormal liver enzyme findings discovered incidentally on routine blood work, pre-operative testing, or health screenings when no liver disease diagnosis is established.
• ✓For tracking and monitoring persistent transaminase elevations in patients on hepatotoxic medications (e.g., statins, methotrexate, anti-epileptics) when no structural liver disease has been confirmed.
• ✓When reporting a clinical finding of transaminitis that drives medical decision-making such as medication dose adjustments, additional testing, or specialist referrals.

Common Coding Mistakes

Related & Differential Codes

Documentation Requirements

• 1Specify which transaminase enzymes are elevated (AST, ALT, or both) and document the actual laboratory values with reference ranges from the performing laboratory.
• 2Record the degree of elevation relative to the upper limit of normal (mild: <5x ULN, moderate: 5-15x ULN, severe: >15x ULN) to support medical necessity for the workup ordered.
• 3Document the clinical context in which the elevation was discovered, including whether it was incidental, part of routine monitoring, or prompted by symptoms such as right upper quadrant pain, jaundice, or fatigue.
• 4Include a differential diagnosis list and document the diagnostic workup plan, such as viral hepatitis serologies, autoimmune markers (ANA, anti-smooth muscle antibody), iron studies, ceruloplasmin, or imaging.
• 5Note any medications the patient is taking that are known to be hepatotoxic, including over-the-counter supplements and herbal remedies, and whether the enzyme elevation correlates with medication initiation or dose changes.
• 6Document prior transaminase levels if available to establish whether the elevation is acute, chronic, or worsening, as this pattern informs the differential diagnosis and urgency of evaluation.
• 7Record the clinical decision-making driven by the finding, such as medication adjustments, referral to hepatology or gastroenterology, or planned follow-up laboratory testing with a specified timeframe.

Reimbursement & Billing Notes

R74.01 is a billable ICD-10-CM code accepted by all payers for claims submission. As a symptom code, it is most commonly used to establish medical necessity for diagnostic workup including laboratory panels (CPT 80076 hepatic function panel, 82040 albumin, 82247 bilirubin total), hepatitis serologies (CPT 86803, 87340, 87341), imaging studies (CPT 76700-76705 abdominal ultrasound, 74178 CT abdomen with contrast), and specialist consultations. Payers generally expect progression from a symptom code to a definitive diagnosis code within a reasonable timeframe.

When R74.01 is used as the primary diagnosis, documentation must clearly demonstrate that the transaminase elevation is the reason for the encounter and that a specific etiology has not yet been established. For ongoing monitoring encounters, include the clinical rationale for continued use of the symptom code rather than a definitive diagnosis. Some payers may request additional documentation or issue queries if R74.01 remains the primary diagnosis over multiple encounters without evidence of a diagnostic workup. Using this code appropriately supports medical necessity for the evaluation and management services billed and helps avoid claim denials for hepatic workup panels and liver imaging.

Frequently Asked Questions