AST/ALT ratio (De Ritis ratio) = AST (U/L) ÷ ALT (U/L).
There is no single normal cut-off for the ratio. The classic reference is a 1979 study of hospital patients with liver disease. The ratio averaged 2.85 in alcohol-related hepatitis and cirrhosis, 1.74 in cirrhosis after other liver injury, 1.3 in chronic hepatitis and 0.74 in viral hepatitis. A ratio above 2 appeared in 70% of the alcohol-related group, 26% of the other cirrhosis group, 8% with chronic hepatitis and 4% with viral hepatitis.
So a ratio above 2 points toward an alcohol-related pattern but does not prove it, and a ratio below 1, where ALT leads, is common in viral hepatitis and fatty liver. In fatty liver research, the BARD score gives points for a ratio above 0.8 when estimating the chance of advanced scarring.
The ratio means most when the enzymes themselves are raised. A gastroenterology guideline puts a truly healthy ALT at 29 to 33 U/L for men and 19 to 25 U/L for women. When both enzymes sit well inside the normal range, the ratio carries little weight. A 2013 review still argues that labs reporting an abnormal ALT should also report AST and the ratio, because together they add both diagnostic and prognostic information.
Timing is a big driver. AST clears from the blood with a half-life of about 18 hours and ALT about 36 hours, so the ratio shifts as a liver problem develops or settles. After several days without alcohol, ALT can overtake AST in alcohol-related hepatitis, which pulls the ratio down.
AST is not liver specific. Muscle also contains it, so hard exercise, a muscle injury or a strenuous training block in the days before a draw can raise AST more than ALT. A sample damaged during collection can raise AST as well.
Methods matter at the margins. Some assays add pyridoxal phosphate, a form of vitamin B6, and people low in that vitamin can show different values on assays without it. Many medicines, including over-the-counter products, can raise liver enzymes, which is why a guideline asks for a full medicine history when enzymes are abnormal. Alcohol intake and body weight also move both enzymes.
A mildly abnormal result is usually repeated before anyone reads much into the ratio. The repeat is most useful with AST and ALT from the same draw, a few days clear of hard exercise, and with alcohol intake noted honestly, since both shape the result. Comparing results from the same lab keeps method differences out of the trend.
A large rise in either enzyme, or raised enzymes with yellowing of the skin or eyes, dark urine, pale stools, abdominal pain or confusion, is worth raising with a clinician promptly rather than waiting for a routine recheck. The guideline lays out further testing for raised enzymes, so the ratio is one clue within that workup.
The 1979 numbers came from hospital patients with established liver disease. They do not translate directly to a healthy person whose enzymes are normal or barely raised. The ratio also cannot separate causes on its own, since a 2013 review notes viral hepatitis can show AST above ALT in severe cases and alcohol-related hepatitis can show ALT above AST once some days have passed.
As a fibrosis test the ratio is better at ruling out than ruling in. In a 2010 study of 145 people with biopsy-proven fatty liver disease, it had a negative predictive value of 93% for advanced scarring, but its positive predictive value was modest. A ratio built from two small numbers can also swing a lot with a change of a few units. An AST of 20 and an ALT of 10 give a ratio of 2, the same as 200 and 100, yet the two situations have nothing in common.
Take AST 42 U/L and ALT 60 U/L from the same draw. The calculator divides AST by ALT, 42 ÷ 60, and the result is 0.70. The ratio is below 1, so ALT leads. That shape is the one the 1979 study saw in viral hepatitis and is common in fatty liver. It also sits below the 0.8 mark the BARD score uses, so that item would add no points.
Both enzymes are above the healthy ALT range the guideline gives for men and women, so the individual values matter more than the ratio here. A second example shows the other direction. AST 120 U/L and ALT 50 U/L give 120 ÷ 50, a ratio of 2.40. That is above 2, the band seen in 70% of the alcohol-related group in 1979, but recent hard exercise or the timing of an illness could produce it too. Either result is one to discuss with a clinician.
Several fibrosis scores fold AST and ALT into a fuller picture. FIB-4 combines age, AST, ALT and platelets. In the 2010 fatty liver study it had the best accuracy for advanced scarring, with an area under the curve of 0.86, ahead of the AST/ALT ratio at 0.83, the NAFLD fibrosis score at 0.81, BARD at 0.77 and the AST to platelet ratio index at 0.67.
The ratio also sits alongside other liver tests. The guideline describes a hepatocellular pattern, where AST and ALT rise more than alkaline phosphatase, and a cholestatic pattern, where alkaline phosphatase leads. GGT and bilirubin add context. The ratio is best read as one quick view inside that wider panel, not as a stand-alone answer. When blood work leaves questions open, the guideline describes imaging next, and a liver biopsy when testing and imaging still do not explain the picture.
The Liver Function panel measures the values this calculator uses. Related: ast, alt, ggt.
Yellowing skin or eyes, dark urine, severe abdominal pain or confusion need urgent medical care rather than a calculator. Beyond that, an AST/ALT ratio calculator divides your AST result by your ALT result to produce the De Ritis ratio, a single number that gives a clinician one clue about the pattern of liver enzyme change.
The ratio is unitless, so by itself it says nothing about how high either enzyme actually is. When AST and ALT both sit inside the typical laboratory range, the ratio is mostly arithmetic. It becomes informative when one or both enzymes are raised, and even then it is read beside the rest of a liver panel, your history, and imaging when a clinician asks for it.
You divide the AST value by the ALT value from the same blood draw, with both numbers in the same units, and the answer is the De Ritis ratio. The calculator above does the arithmetic, but the inputs matter more than the division.
AST stands for aspartate aminotransferase, written on older reports as SGOT. ALT stands for alanine aminotransferase, written on older reports as SGPT. Both are enzymes that live inside cells and leak into blood when those cells are stressed or damaged. The difference between them is where they live. ALT is concentrated mainly in liver cells, which makes it the more liver-specific of the two. AST is found in the liver as well, but also in heart muscle, skeletal muscle, kidney tissue and red blood cells, so an AST result can reflect something happening well outside the liver.
Two worked examples show how fast the number moves. An AST of 30 U/L with an ALT of 60 U/L gives a ratio of 0.5. Reverse those values, AST 60 U/L and ALT 30 U/L, and the ratio is 2.0. Same enzymes, same magnitude of change, completely different pattern. Research suggests that the ratio first described by De Ritis has kept a place in clinical biochemistry precisely because it summarises that pattern, not because it works as a stand-alone test 1.
For the arithmetic to mean anything, both values should come from the same blood draw, reported in the same units (U/L, sometimes printed as IU/L), and ideally from the same laboratory. Mixing an AST from one draw with an ALT from another, weeks apart, produces a number that describes nothing real.
| Marker | Typical adult lab reference range | What it reflects |
|---|---|---|
| AST (SGOT) | roughly 10 to 40 U/L | Liver cells, but also heart and skeletal muscle, kidney and red blood cells |
| ALT (SGPT) | roughly 7 to 56 U/L | Concentrated mainly in liver cells, so more liver specific |
| AST/ALT ratio | no single reference range, commonly sits near 1 | Unitless pattern marker, interpreted with the enzyme values themselves |
These are typical laboratory reference ranges, and they vary by laboratory, assay method, age and sex. Many labs publish lower upper limits for women than for men. Always read the range printed on your own report rather than a general one.
One more piece of background helps the ratio make sense. AST clears from the bloodstream faster than ALT does, so the same injury can produce a different ratio depending on when the blood was drawn relative to the event 1. A ratio measured during an acute insult and a ratio measured a week later are not describing the same moment.
The ratio carries real information only when at least one of the two enzymes is outside the typical range. Everything below assumes that condition, and none of it is a diagnosis.
Both AST and ALT inside the typical range. The ratio is close to noise. An AST of 20 U/L over an ALT of 10 U/L gives 2.0, a number that looks dramatic and usually means nothing, because small values divided by smaller values swing wildly. Clinicians generally ignore the ratio in this situation and look at the trend of the enzymes themselves over time.
A ratio below about 1 with raised enzymes. This is an ALT-predominant pattern, the most common picture seen in routine testing. It is frequently described in metabolic and fatty liver change, in several viral causes of hepatitis, and in medication or supplement effects on the liver. The pattern narrows the list of possibilities, it does not identify a cause.
A ratio around 1 to 2 with raised enzymes. This is the least specific zone. Many causes overlap here, and the number on its own rarely moves a clinician in one direction. Context, the height of the enzymes, and the rest of the panel do the work.
A ratio above about 2 with raised enzymes. Historically this is the pattern most associated with alcohol-related liver injury, often with enzyme levels that are only moderately raised rather than extreme 2. Studies suggest that a higher De Ritis ratio is associated with alcohol-related liver disease among patients being investigated for liver injury 2. Research suggests that the De Ritis quotient read together with gamma-glutamyltransferase may help separate alcohol-related liver parenchymal damage from other causes 3. A high ratio is still only a prompt to ask questions, and the same pattern appears for other reasons, including muscle sources of AST.
A ratio that drifts upward over time in known chronic liver disease. As scarring advances, ALT often falls while AST holds steadier, so the ratio climbs 1. That is why the ratio appears inside several non-invasive fibrosis scores 4. Studies suggest that simple scores built from routine bloods, including FIB-4, APRI and the AST/ALT ratio, perform differently from transient elastography when hepatic fibrosis is assessed in non-alcoholic fatty liver disease 4. None of these scores replaces the assessment a clinician makes with imaging and the full clinical picture.
A markedly elevated ratio. Research suggests that a strikingly high AST to ALT ratio is associated with hepatic neoplasia in some patients whose enzymes are under investigation, which is one reason clinicians do not dismiss an extreme value 5. Extreme ratios also appear with muscle breakdown, a haemolysed blood sample, and other non-liver sources, so the finding is a reason for a careful workup rather than a conclusion.
Interest outside the liver. A broad 2024 review describes growing study of the De Ritis ratio in cardiology, oncology and critical care settings, where the evidence base is early and mixed rather than established 6. Treat those uses as open questions, not as something to read into your own result.
The practical way to use any of this is the same three-step logic a good clinician uses. Observe what the number shows, consider what it may reflect given everything else on the report, then take it to someone qualified to interpret it. A ratio is an observation, never a verdict.
A ratio inherits every source of error in both enzymes, then adds the instability of dividing one by the other. Several things push it around.
The durable rule is simple. Trends at one laboratory beat single values, and the enzyme levels themselves always outrank the ratio derived from them.
The ratio belongs inside a liver panel, never on its own. A clinician reading it will typically also want alkaline phosphatase and gamma-glutamyltransferase, which help separate a cholestatic pattern from a hepatocellular one, bilirubin, albumin, platelet count and clotting measures, which say more about how the liver is functioning than how irritated it is. Creatine kinase helps test whether muscle is contributing to a raised AST. Beyond the liver panel, metabolic markers such as fasting glucose, HbA1c, triglycerides and HDL, plus iron studies and ferritin, often shape the interpretation, and viral hepatitis testing or imaging may be requested depending on the picture.
If you want the marker page for this specific value, with the pattern bands laid out beside the underlying enzymes, read the AST:ALT Ratio biomarker entry.
AST and ALT are standard components of a liver panel, which is why most people already have the two numbers this calculator needs sitting on an existing report. The FitScript Liver Function panel measures them alongside the other liver markers that give the ratio context, and FitScript members have 150+ biomarkers tested per year, with results interpreted by Atlas, the AI health advisor, and reviewed in the context of the rest of their biology. Any treatment decision that follows is made by a licensed provider who evaluates whether it is appropriate for the individual.
Promptly, if your enzymes are outside the standard range and staying there, if the ratio has shifted meaningfully between two tests at the same laboratory, or if liver results are abnormal alongside symptoms such as persistent fatigue, nausea, right upper abdominal discomfort, easy bruising or unexplained weight change. Yellowing of the skin or eyes, dark urine, severe abdominal pain or confusion are reasons to seek urgent medical care, not to repeat a calculation. Never ignore an abnormal liver result because the ratio looked reassuring, and never treat a suboptimal value as a diagnosis, because the pattern needs a person who can see your history, medications, alcohol intake, training load and imaging. This page is educational and is not medical advice. Discuss your own results, and any treatment that may follow from them, with a clinician or licensed provider.
For more background on each enzyme on its own, read what is sgot ast blood test and when to worry about alt levels.
There is no single cut-off. Research has used a ratio above 2 as a pointer toward alcohol-related liver disease, and your lab's ranges for AST and ALT come first.
AST has a half-life in blood of about 18 hours and ALT about 36 hours, so the ratio shifts as a liver problem develops or settles.
No. AST and ALT are on standard liver and metabolic panels.
With raised enzymes, a ratio above roughly 2 is the pattern most often associated with alcohol-related liver injury. It is a prompt for further questions, not a diagnosis. The same pattern can appear with advanced scarring of any cause, with muscle injury raising AST, or with a haemolysed sample.
A ratio below about 1 with raised enzymes means ALT is higher than AST, an ALT-predominant pattern. It is described frequently in metabolic and fatty liver change, in several viral causes of liver inflammation, and with some medication or supplement effects. The pattern narrows the possibilities for a clinician rather than naming a cause, so it needs the rest of the panel to be useful.
Yes. SGOT is the older name for AST and SGPT is the older name for ALT, so an SGOT/SGPT ratio calculator and an AST/ALT ratio calculator do exactly the same arithmetic. The De Ritis ratio is simply the name given to AST divided by ALT after the clinician who first described the pattern.
Yes, and this is one of the most common reasons a ratio looks odd in otherwise healthy people. AST is present in skeletal muscle as well as liver, so heavy resistance training, unaccustomed eccentric work, long endurance sessions and muscle injury can raise AST more than ALT and push the ratio upward. Creatine kinase is usually checked alongside to test whether muscle is the source.
No. The ratio is a pattern marker, not a measure of liver health, and significant liver disease can exist with enzymes and a ratio that look unremarkable. Liver function is better assessed with the wider panel, including bilirubin, albumin, clotting measures and platelet count, together with imaging when a clinician considers it appropriate.
Not by itself. The ratio appears inside non-invasive scoring tools such as FIB-4 and APRI, and these simple blood-based scores may perform differently from transient elastography when fibrosis is assessed in non-alcoholic fatty liver disease. They are screening aids that help a clinician decide who needs further imaging or specialist assessment, not substitutes for it.
That is a clinical decision rather than a fixed schedule, and it depends on how far outside the range the values sit, whether symptoms are present, and what else is on the panel. If a repeat test is being arranged, it helps to use the same laboratory and to avoid heavy training in the days beforehand, so the comparison reflects your biology rather than assay differences or muscle stress.