What is the AST/ALT ratio (De Ritis ratio)?

The AST/ALT ratio, also called the De Ritis ratio after Italian physician Ferdinando De Ritis who described it in the 1950s, is the mathematical ratio of AST (aspartate aminotransferase) to ALT (alanine aminotransferase). It is used as an adjunct marker in liver disease pattern recognition — not as a standalone diagnostic test.

What is the normal AST/ALT ratio?

In healthy individuals, AST and ALT are roughly similar, giving a ratio close to 1.0 (typical range 0.7–1.2). A ratio 2 is classically associated with alcoholic liver disease. In cirrhosis from any cause, the ratio tends to rise above 1.0.

What does AST/ALT ratio >2 indicate?

Ratio >2 (De Ritis ratio) is classically associated with alcoholic liver disease and was validated by Cohen and Kaplan (Gastroenterology 1979). Ratio >3 is more specifically suggestive of alcoholic hepatitis. However, the ratio lacks sufficient sensitivity/specificity to be diagnostic alone — always combine with clinical history, GGT, ALP, and additional liver workup.

What does AST/ALT ratio show in hepatitis?

In viral hepatitis (hepatitis A, B, C), ALT elevation typically exceeds AST, producing a ratio 1 in viral hepatitis may indicate concurrent alcoholic injury or advanced fibrosis/cirrhosis as a complication.

How do I interpret abnormal liver function tests (LFTs)?

Step 1: Pattern — hepatocellular (AST/ALT dominant) vs cholestatic (ALP/GGT dominant) vs mixed? Step 2: AST:ALT ratio — 2 suggests alcohol/cirrhosis. Step 3: Degree of elevation — mild ( 10x)? Step 4: Context — medications, alcohol history, obesity, family history, comorbidities. Step 5: Additional tests — hepatitis serologies, GGT, bilirubin, INR, albumin, CBC, imaging.

Can elevated AST come from muscle injury rather than the liver?

Yes. AST is present in skeletal muscle, cardiac muscle, red blood cells, kidney, and brain. Myocardial infarction, rhabdomyolysis (from trauma, intense exercise, myopathy, drug-induced), or hemolysis can produce AST elevations with normal or minimally elevated ALT — yielding high AST:ALT ratios unrelated to liver disease. Always check CK and troponin when AST elevation seems disproportionate or the clinical picture doesn't fit liver disease.

What is the role of GGT in alcoholic liver disease assessment?

GGT (gamma-glutamyl transferase) is elevated in approximately 70-80% of patients with alcoholic liver disease, often disproportionately to AST and ALT. It is induced by alcohol independently of hepatocellular injury (enzyme induction). GGT >3-5x ULN combined with AST:ALT >2 and clinical history of alcohol use strongly supports alcoholic liver disease. GGT normalizes within 4-6 weeks of abstinence, making it a useful sobriety marker.

What does AST/ALT ratio show in NAFLD?

In early NAFLD (steatosis only), the ratio is typically <0.8 with ALT-dominant elevation. As fibrosis progresses (F2-F3), the ratio approaches 1.0. In NAFLD-associated cirrhosis, the ratio commonly exceeds 1.0. A rising AST:ALT ratio in a known NAFLD patient is a clinical signal to calculate FIB-4 or NAFLD Fibrosis Score and consider elastography referral.

When should I refer a patient with abnormal LFTs to a hepatologist?

Refer to hepatology for: transaminases >3x ULN persisting >6 months; any evidence of cirrhosis (thrombocytopenia, splenomegaly, ascites, elevated INR, low albumin); FIB-4 >2.67 or APRI >1.5; suspected autoimmune hepatitis (ANA, ASMA positive); Wilson disease or hemochromatosis; unexplained cholestatic pattern (ALP >3x ULN); clinical features of decompensation; or when the diagnosis remains uncertain after initial workup.

Online Medical Tools — AST/ALT Ratio

Printed on 9/2/2026

For informational purposes only. This is not medical advice.

Gastroenterology

AST/ALT Ratio

The AST/ALT (De Ritis) ratio is a simple enzyme ratio used as an adjunct in liver disease pattern assessment. Different ratio ranges can suggest different injury patterns but must be interpreted with full laboratory and clinical context.

Formula: AST/ALT Ratio = AST / ALT.

AST

U/L

ALT

U/L

Save your results with a free account

Keep a history of calculations, favorite tools, and access your dashboard anytime.

Create free account Sign in

How It Works

Enter AST and ALT from liver function panel

Obtain AST (aspartate aminotransferase) and ALT (alanine aminotransferase) levels from the patient's basic metabolic panel or comprehensive metabolic panel — two of the most commonly ordered liver function tests. Ensure both values are from the same blood draw and expressed in the same units (U/L). These are standard components of every routine chemistry panel.

Calculate the AST:ALT ratio by simple division

Divide AST by ALT to obtain the De Ritis ratio. For example, AST 80 U/L ÷ ALT 40 U/L = ratio of 2.0. The calculation is straightforward — no logarithms or additional variables required. The result is a dimensionless ratio that indicates which enzyme is relatively more elevated.

Interpret the ratio pattern in clinical context

Use the ratio as one component of liver injury pattern recognition: Ratio <0.8 = typical of non-alcoholic causes (NAFLD, viral hepatitis) where ALT predominates. Ratio ~1.0 = equivocal; may represent advanced NAFLD fibrosis or mixed injury. Ratio 1.0–2.0 = suggestive of increasing fibrosis or early alcoholic injury. Ratio >2.0 = classically associated with alcoholic liver disease (De Ritis ratio). Ratio >3.0 = strongly suggestive of alcoholic hepatitis. Importantly, in cirrhosis from any cause (viral, NAFLD, autoimmune), the ratio tends to rise above 1.0 as fibrosis replaces hepatocytes. Always combine with GGT, ALP, bilirubin, INR, and clinical history.

Who Uses the AST/ALT Ratio

Differentiating Alcoholic vs Non-Alcoholic Liver Disease

Primary care physicians and hepatologists

The De Ritis ratio >2.0 is a classic screening marker for alcoholic liver disease. Combined with elevated GGT, clinical history of alcohol use, and elevated MCV, it supports — but does not confirm — alcohol-related hepatocellular injury.

Cirrhosis Progression Marker

Hepatologists and gastroenterologists

As NAFLD, HCV, or other chronic liver diseases progress from simple steatosis to cirrhosis, the AST:ALT ratio rises from below 1 toward and above 1. A rising ratio over serial measurements in a known chronic liver disease patient suggests advancing fibrosis.

Liver Disease Pattern Recognition in Primary Care

Primary care physicians and hospitalists

Use the ratio to quickly characterize the liver injury pattern when a patient presents with abnormal LFTs: ALT > AST (ratio <1) points toward NAFLD, viral hepatitis, or drug-induced liver injury; AST > ALT (ratio >2) prompts alcohol history and GGT measurement.

Evaluating Abnormal LFTs — First Interpretation Step

All clinicians ordering liver function panels

When faced with elevated AST and ALT, the AST:ALT ratio is the first pattern-recognition step. It narrows the differential diagnosis and guides which additional tests to order: GGT for alcohol, hepatitis serologies for viral disease, ANA/ASMA for autoimmune hepatitis, ceruloplasmin for Wilson disease.

Hepatocellular vs Cholestatic Injury Pattern

Hospitalists and internists

Elevated AST and ALT with ratio >1 vs elevated ALP and GGT: the pattern distinguishes hepatocellular injury (AST/ALT dominated) from cholestatic injury (ALP/GGT dominated). Combining both patterns helps localize injury to hepatocytes vs bile ducts.

Pro Tips

De Ritis ratio >2 for alcoholic liver disease is a screening tool, NOT a diagnosis

The classic threshold of AST:ALT >2 for alcoholic liver disease has sensitivity of approximately 54% and specificity of approximately 70% — meaning nearly half of alcoholic liver disease cases have a ratio <2, and 30% of non-alcoholic cases have a ratio >2. It is a pattern-recognition aid, not a standalone diagnostic test. Always integrate with GGT, clinical alcohol history, and additional testing.

Always obtain GGT (gamma-glutamyl transferase) alongside the ratio

GGT is elevated disproportionately in alcoholic liver disease (induced by alcohol independently of hepatocyte injury) and more specifically than AST/ALT alone. A GGT that is 3-5x the upper limit of normal, combined with AST:ALT >2, strongly supports alcoholic liver disease. GGT normalization after abstinence (within 4-6 weeks) can also be used to assess treatment response.

In viral hepatitis, ALT typically exceeds AST — ratio is usually <1

Hepatitis A, B, and C characteristically produce a pattern where ALT is higher than AST (hepatocytes preferentially release ALT). An AST:ALT <1 in a patient with transaminase elevations should prompt hepatitis serology testing. If the ratio is >1 in viral hepatitis, consider advanced fibrosis as a contributor.

In NAFLD, the ratio is usually <1 early but rises toward 1 as fibrosis advances

Early NAFLD (steatosis only) typically shows ratio <0.8 with ALT-dominant elevation. As fibrosis progresses toward F2-F3 and cirrhosis, the ratio approaches and exceeds 1.0. A rising AST:ALT ratio in a known NAFLD patient is a signal to calculate FIB-4 and consider FibroScan.

B6 deficiency in alcoholics lowers ALT independently of liver disease severity

ALT synthesis requires pyridoxal-5'-phosphate (vitamin B6) as a cofactor. Alcoholics are frequently B6-deficient, which impairs ALT synthesis and artificially lowers ALT levels — thereby artificially elevating the AST:ALT ratio even in the absence of severe hepatocellular injury. This was documented by Diehl et al. (Gastroenterology 1984) and partially explains why alcoholic liver disease cases have elevated ratios.

In cirrhosis from any cause, ratio rises above 1

Fibrosis replaces functional hepatocytes, disproportionately reducing ALT (which is almost exclusively hepatic) compared to AST (which has significant cardiac and muscle sources). This means that in end-stage liver disease from NAFLD, HCV, HBV, autoimmune hepatitis, or PBC/PSC, the ratio commonly exceeds 1.0 even without alcohol use.

Muscle damage (rhabdomyolysis, cardiac injury) elevates AST without liver involvement

AST is found in skeletal muscle, cardiac muscle, red blood cells, kidney, and brain — not just the liver. Myocardial infarction, rhabdomyolysis, vigorous exercise, or myopathy can produce AST elevations with normal ALT, yielding very high AST:ALT ratios. Always check creatine kinase (CK) and cardiac troponins when AST elevation is unexplained or disproportionate.

ALP and GGT elevation alongside ratio helps identify cholestatic vs hepatocellular pattern

Isolated elevation of ALP and GGT with normal or mildly elevated transaminases suggests cholestatic injury (bile duct obstruction, PBC, PSC, drug cholestasis). Elevated transaminases with relatively normal ALP suggests hepatocellular injury. The ratio helps within the hepatocellular category to suggest alcohol vs non-alcohol.

Common Questions About Your Results

Non-alcoholic causes of AST:ALT >2 include: (1) Cirrhosis from any etiology (NAFLD, viral hepatitis, autoimmune) where fibrosis displaces hepatocytes; (2) Cardiac or skeletal muscle injury elevating AST — check CK and troponin; (3) Hemolysis releasing red cell AST; (4) Thyroid disease (hypothyroidism elevates CK and AST); (5) Celiac disease in some cases. Do not assume alcoholic liver disease without additional supporting evidence.

Yes. Several medications and supplements affect AST and/or ALT levels: phenytoin and carbamazepine induce hepatic enzymes and can elevate GGT and ALT; statins elevate transaminases in some patients; niacin, amiodarone, methotrexate, and many other drugs affect AST and ALT to different degrees. Drug-induced liver injury (DILI) typically produces an ALT-dominant pattern (low ratio), but some hepatotoxins cause AST-dominant injury. Always review the medication list.

Evidence-Based Methodology

The AST/ALT (De Ritis) ratio was described by De Ritis et al. in Italy in the 1950s as a hepatocellular injury marker. The ratio >2 for alcoholic hepatitis was validated by Cohen and Kaplan (Gastroenterology 1979) in a prospective study of liver disease etiology. Pyridoxine (B6) deficiency effects on ALT in alcoholics were characterized by Diehl et al. (Gastroenterology 1984). The ratio has AUROC approximately 0.75 for alcoholic vs non-alcoholic liver disease and should be interpreted with GGT, clinical history, and full hepatic assessment.

Clinical Content Trust

Last reviewed:: April 21, 2026
Guideline version:: General evidence framework v2026.04
Source set version:: Primary-source set v1

How to Interpret Your Result

The ratio helps describe liver enzyme pattern but should be interpreted alongside absolute AST/ALT values and full hepatic assessment.

When to Use This Tool

Use as a quick adjunct in liver enzyme interpretation, chronic liver disease follow-up, and hepatology triage discussions.

Limitations

The ratio is non-specific and influenced by non-hepatic AST sources (muscle injury, hemolysis), assay timing, and mixed disease processes.

For related assessments, see FIB-4, MELD Score and Child-Pugh Score.

Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.

Changelog

April 21, 2026 · trust-baseline
Clinical trust metadata enabled for this tool page with structured review/version fields.

Related Tools

Gastroenterology

FIB-4

Estimate liver fibrosis risk using age, AST, ALT, and platelet count with the FIB-4 index.

Open Clinical

MELD Score

Calculate the MELD and MELD-Na scores to assess liver disease severity and transplant priority. Uses bilirubin, INR, creatinine, and sodium.

Open Clinical

Child-Pugh Score

Calculate the Child-Pugh score to classify the severity of chronic liver disease and estimate prognosis. Uses bilirubin, albumin, INR, ascites, and encephalopathy.

Open Gastroenterology

AIMS65

Estimate in-hospital mortality risk in upper GI bleeding using the 5-item AIMS65 score.

Open

Frequently Asked Questions

ALT (alanine aminotransferase) is found almost exclusively in the liver, making it a relatively liver-specific marker. AST (aspartate aminotransferase) is found in liver, cardiac muscle, skeletal muscle, red blood cells, kidney, and brain. Therefore, elevated AST with normal ALT often indicates non-hepatic injury (myocardial infarction, rhabdomyolysis), while isolated ALT elevation is more likely hepatic.

The De Ritis ratio (AST/ALT) was originally described by De Ritis, Coltorti, and Giusti in Italy in the 1950s as a marker of hepatocellular injury severity. Its clinical significance lies in pattern recognition: ratio <1 suggests non-alcoholic hepatocellular injury; ratio >2 suggests alcoholic injury or cirrhosis. It remains a widely taught and used bedside hepatology tool despite its limitations.

In cirrhosis from any etiology (NAFLD, viral hepatitis, autoimmune hepatitis, PBC/PSC, alcohol), the AST:ALT ratio commonly rises above 1.0 and often above 2.0. This occurs because cirrhosis reduces the absolute number of functional hepatocytes, disproportionately lowering ALT (which is almost exclusively hepatic) while AST remains elevated from residual liver injury and other sources. A rising ratio in a known chronic liver disease patient signals advancing fibrosis.

Online Medical Tools — AST/ALT Ratio

AST/ALT Ratio

How It Works

Enter AST and ALT from liver function panel

Calculate the AST:ALT ratio by simple division

Interpret the ratio pattern in clinical context

Who Uses the AST/ALT Ratio

Differentiating Alcoholic vs Non-Alcoholic Liver Disease

Cirrhosis Progression Marker

Liver Disease Pattern Recognition in Primary Care

Evaluating Abnormal LFTs — First Interpretation Step

Hepatocellular vs Cholestatic Injury Pattern

Pro Tips

De Ritis ratio >2 for alcoholic liver disease is a screening tool, NOT a diagnosis

Always obtain GGT (gamma-glutamyl transferase) alongside the ratio

In viral hepatitis, ALT typically exceeds AST — ratio is usually <1

In NAFLD, the ratio is usually <1 early but rises toward 1 as fibrosis advances

B6 deficiency in alcoholics lowers ALT independently of liver disease severity

In cirrhosis from any cause, ratio rises above 1

Muscle damage (rhabdomyolysis, cardiac injury) elevates AST without liver involvement

ALP and GGT elevation alongside ratio helps identify cholestatic vs hepatocellular pattern

Common Questions About Your Results

Evidence-Based Methodology

Clinical Content Trust

How to Interpret Your Result

When to Use This Tool

Limitations

Changelog

Related Tools

FIB-4

MELD Score

Child-Pugh Score

AIMS65

Further Reading

A Complete Guide to Gastroenterology and Digestive Health

Frequently Asked Questions