AST/ALT Ratio Calculator (De Ritis)

Use the AST/ALT Ratio Calculator

Enter AST and ALT from the same report to compute the De Ritis index and review plain‑language patterns.

How to Use AST/ALT Ratio Calculator (De Ritis)

1. Step 1: Enter AST

   Type your AST value (U/L) from the same lab report.

2. Step 2: Enter ALT

   Type your ALT value (U/L) from that report; do not mix dates.

3. Step 3: Calculate

   Tap Calculate to get the AST/ALT ratio instantly.

4. Step 4: Compare Pattern

   Review the ratio category (<1, ~1, ≥2) alongside context notes.

5. Step 5: Reset if Needed

   Use Reset to try another set of numbers or correct a typo.

Key Features

• AST/ALT ratio
• Interpretation guide
• Reference ranges
• Clinical context notes
• Mobile‑first inputs

Understanding Results

AST/ALT Ratio Calculator: Formula

The AST/ALT ratio is a straightforward division: AST ÷ ALT, where both enzymes are reported in U/L from the same blood draw. AST stands for aspartate aminotransferase and ALT stands for alanine aminotransferase. The ratio helps describe patterns seen in liver and non‑liver conditions, but it is not a diagnosis by itself.

Enter your two numbers from one lab report (do not mix different dates), tap Calculate, and the tool displays your ratio to two decimals along with a plain‑English category.

Reference Ranges & Interpretation

There is no single universal “normal” AST/ALT ratio because context matters. In many healthy adults, ALT can be similar to or slightly higher than AST, which yields a ratio at or below 1. A ratio between 1 and 2 is considered borderline and must be read alongside absolute enzyme values. A ratio of 2 or more has been described in patterns seen with alcoholic hepatitis or advanced fibrosis, but many other factors can influence the ratio.

• Ratio < 1: ALT often exceeds AST. Seen across non‑alcoholic or viral liver conditions and in many benign states.
• Ratio ≈ 1: Balanced elevation; could be chronic liver disease or near‑normal profile depending on absolute values.
• Ratio ≥ 2: Pattern described in alcoholic hepatitis or advanced fibrosis; not diagnostic alone.

Always pair the ratio with the absolute values (how high AST and ALT are relative to your lab’s reference ranges), medication history, alcohol exposure, recent exercise, and other labs. Discuss questions with a clinician who can evaluate the full picture.

Assumptions & Limitations

The ratio assumes both numbers are from the same sample and expressed in U/L. If ALT is 0 (or unreadable), the ratio is undefined. AST is present in skeletal and cardiac muscle, so intense exercise, muscle injury, or hemolysis can raise AST more than ALT and inflate the ratio without a primary liver problem. The ratio is a descriptive aid — not a diagnostic test — and should not be used to self‑diagnose or change treatment.

Complete Guide: AST/ALT Ratio Calculator (De Ritis)

Compute the De Ritis index with the AST/ALT ratio calculator to support liver disease evaluation. Compare results with patterns seen in clinical settings. The tool is fast and mobile‑friendly, and it keeps the computation transparent: one ratio, shown with a short interpretation and clear notes about context. It is not a diagnosis. Use it to organize information from your lab report and prepare better questions for a clinician.

If you are browsing a lot of tools today, keep our complete calculators index handy. You can also explore our dedicated liver function calculator if you want to look beyond AST and ALT.

What the AST/ALT ratio means

The AST/ALT ratio — sometimes called the De Ritis index — is the result of dividing aspartate aminotransferase (AST) by alanine aminotransferase (ALT). Both are enzymes measured in blood and reported in units per liter (U/L). The ratio highlights relative changes between the two enzymes. In clinical discussions, patterns like “less than 1,” “around 1,” and “two or higher” show up because they loosely map to groups of conditions. However, no single number guarantees a diagnosis. That is why the result in this calculator is paired with context notes rather than a definitive label.

AST is found in liver, but also in skeletal and cardiac muscle, kidneys, brain, and red blood cells. ALT is more liver‑specific. Because AST can rise from non‑liver causes, the ratio can shift even when the liver is not the primary source of the enzyme change. This is a helpful reminder to consider the whole picture: symptoms, timing, medications, alcohol exposure, exercise, and other labs.

AST vs. ALT basics

Most laboratories report reference intervals for AST and ALT with upper limits of normal (ULN) commonly in the ~30–40 U/L range for adults. Labs differ by method and population, so your printout is the authority for your result. Mild elevations are common and can be transient. Sustained or substantial changes deserve follow‑up with a clinician who can review history, exposures, and other tests.

ALT tends to be elevated more than AST in many non‑alcoholic and viral liver conditions; that makes the ratio less than 1 a frequent finding. When AST is much higher than ALT (ratio ≥ 2), it raises the possibility of a pattern described in alcoholic hepatitis or advanced fibrosis, especially when absolute numbers fit the picture (e.g., AST not extremely high). These are patterns — not rules — and exceptions are common.

How to use the calculator

Grab your lab report and enter the AST and ALT from the same blood draw. Values should be in U/L. Tap Calculate. You will see the ratio to two decimal places, a category label, and context notes summarizing what ranges often suggest. If you entered a number incorrectly, use Reset and try again. For broader context, try our Child‑Pugh score or MELD score pages where applicable, noting that those scores serve different purposes than a simple ratio.

Interpreting common ranges

Ratio < 1: ALT is higher than AST. This pattern appears in many situations, including non‑alcoholic fatty liver disease, chronic viral hepatitis, medication effects, and sometimes in healthy people with small, temporary elevations. Interpretation depends on absolute values: ALT of 42 with AST of 35 has a similar ratio to ALT of 420 with AST of 350, but the clinical implications differ dramatically.

Ratio ≈ 1: AST and ALT are similar. This can reflect near‑normal results when both numbers are within the lab’s reference interval or a broad set of chronic conditions when both are elevated. Context — symptoms, alcohol use, viral testing, metabolic factors — guides next steps.

Ratio ≥ 2: A ratio of two or higher has been historically associated with a pattern seen in alcoholic hepatitis and some cases of advanced fibrosis. That said, ratio alone is not specific. AST has non‑hepatic sources; muscle injury, hemolysis, or strenuous exercise can push AST higher than ALT and mimic this pattern. The absolute numbers, bilirubin, INR, albumin, platelets, and history help interpret what is going on.

Patterns seen in common conditions

The ratio is one of many clues. Here are general tendencies clinicians often consider, paired with the caveat that real cases do not always follow the textbook:

• Alcohol‑related patterns: AST can be higher than ALT, sometimes producing a ratio ≥ 2, with AST often not extremely high.
• Metabolic liver disease (e.g., NAFLD/NASH): ALT may predominate, yielding a ratio < 1; obesity and insulin resistance are common contributors. For weight context, see our BMI calculator.
• Viral hepatitis: Either enzyme can be elevated; acute spikes can be large. Ratios vary and are not diagnostic by themselves.
• Cholestatic patterns: ALP and bilirubin may be more informative than the AST/ALT ratio.
• Muscle injury or intense exercise: AST may rise because it is present in skeletal muscle, shifting the ratio higher without liver injury.

When broader liver function is a concern, clinicians look at additional markers. For educational context, compare our liver function calculator and risk‑oriented scores such as Child‑Pugh and MELD — they serve a different purpose than a simple enzyme ratio but help illustrate how multiple labs fit together.

Limits and edge cases

The AST/ALT ratio cannot by itself identify the cause of enzyme changes or the severity of any illness. Some important limitations include: (1) lab method differences; (2) extra‑hepatic AST from muscle, red cells, and heart; (3) timing — values change over hours to days; (4) medications and supplements; (5) pregnancy or underlying conditions that affect liver tests. When ALT is zero or unreadable, the ratio is undefined, and any automatic computation will display an error.

Vigorous exercise can transiently increase AST (and to a lesser extent ALT) due to muscle micro‑injury. If you trained hard the day before your blood draw, numbers may look higher than your usual baseline. Many clinicians recommend avoiding heavy training for 24–48 hours before repeat testing to reduce this confounder.

Hemolysis during phlebotomy — when red blood cells break in the sample tube — can also falsely elevate AST. Lab reports often flag hemolysis; if present, repeating the test may be warranted. These technical details reinforce why trends and clinical context matter more than a single outlier value.

If a result seems out of character, repeat testing under steady conditions and review with a professional who can integrate history and exam. A single ratio should start questions, not end them.

If you track alcohol consumption, you might also find our alcohol units calculator helpful for estimating grams of alcohol across drink types. That kind of information — while not diagnostic — can add practical context to lab discussions.

How it compares with other liver tools

This page focuses on a single ratio. Non‑invasive scores and risk tools combine several labs and clinical features to estimate severity or outcomes. For example, MELD uses bilirubin, INR, and creatinine (± sodium) to estimate mortality risk in advanced disease. Child‑Pugh includes labs and clinical findings to stage cirrhosis. None of these are interchangeable with the AST/ALT ratio, which is primarily descriptive and educational. Still, comparing them side by side helps you see how labs fit into broader reasoning.

Next steps and follow‑up

If your numbers are new or unexpected, repeating the tests after a short interval (as advised by your clinician) is common. Bring a list of medications and supplements, note alcohol use, recent infections, heavy exercise, and any new symptoms. Over time, trends — not one number — tend to be most informative. If you are building a personal dashboard of health stats, bookmark our calculators hub so you can revisit tools you find useful.

For day‑to‑day life, a simple checklist helps: schedule labs when you are well‑rested, avoid strenuous training the day before, hydrate normally, and keep meals routine. If your clinician suggests a repeat draw, try to match conditions so comparisons are fair. Pair enzyme results with symptoms, physical exam, and other labs rather than drawing big conclusions from the ratio alone.

Authoritative introductions to AST and ALT tests are available from public, non‑commercial sources. For example, see MedlinePlus: liver function tests, and ALT testing. These are broad resources (not personalized medical advice) that explain how enzymes are measured and interpreted in clinical practice.

As you track numbers over time, keep notes in the same place you record results — include sleep, training, alcohol, new medications, and symptoms. Patterns in these notes often explain short‑term bumps in AST or ALT. When you share the log with a clinician, it saves time and makes follow‑up plans easier to agree on.

Common questions

You will also find a dedicated FAQ near the bottom of this page with short answers to frequent questions, including how exercise, fasting, and measurement differences can influence the AST/ALT ratio. If a question here sparks something specific to your situation, bring it to your clinician so they can consider the full context.

Frequently Asked Questions