What is a De Ritis (AST / ALT) Ratio Blood Test?

Comparing Two Transaminases to Localize Cell Injury

The De Ritis ratio is the proportion of two liver-related enzymes measured in blood: aspartate aminotransferase (AST) and alanine aminotransferase (ALT). These enzymes are catalysts in amino acid metabolism (transaminases). ALT is concentrated in liver cells (hepatocytes) and mainly resides in the cell fluid (cytosol). AST is found in many tissues—including liver, heart, and muscle—and exists in both cytosolic and mitochondrial forms. When cells are stressed or injured, AST and ALT leak into the bloodstream; the ratio compares their relative presence.

What the ratio reflects is the pattern of tissue injury rather than just its size. Because ALT is more liver-specific and AST is more widely distributed—and partially mitochondrial—the balance between them signals where the enzyme release is coming from and what kind of cellular compartments are involved. In practice, the De Ritis ratio helps frame whether a signal is predominantly hepatic versus extrahepatic, and whether the liver stress has a more cytosolic or mitochondrial signature. By turning two related enzyme readings into a single comparison, it adds biological context to liver enzyme changes and sharpens the picture of hepatocellular stress.

What the De Ritis Pattern Reveals About Liver Injury

The De Ritis ratio compares two liver enzymes—AST divided by ALT—to show where injury is coming from and how the liver (and sometimes muscle) is responding. Because AST lives in liver mitochondria and in muscle, while ALT is more specific to liver cells, their balance helps sort metabolic stress, toxic injury, and scarring from extrahepatic sources.

Big picture, the De Ritis ratio links liver cell biology to whole‑body context—alcohol exposure, metabolic health, muscle status, and scarring risk. Used with GGT, bilirubin, platelets, INR, and CK, it refines the likelihood of steatohepatitis, alcoholic liver disease, or fibrosis and helps anticipate long‑term risks such as cirrhosis and its complications.

Below 0.8, Near 1, Above 1.5–2: Pattern Recognition

Most healthy people sit around 0.8–1.2, with an within reference ranges value near the middle of that range. Interpretation always works most appropriately alongside the absolute AST and ALT levels. In healthy adults the ratio commonly centers near 1, often slightly below. This pattern is consistent with intact hepatocellular and mitochondrial function and steady metabolic throughput. The De Ritis (AST/ALT) ratio compares two enzymes released from cells when they are stressed or injured. ALT is more liver-specific, while AST is present in liver plus heart, skeletal muscle, kidney, and red blood cells. The ratio helps localize injury and gauge its pattern—information that relates to energy production, glucose and lipid metabolism, protein synthesis, detoxification, and, when muscle is involved, cardiovascular and musculoskeletal status.

When the ratio trends below about 0.8, ALT predominates, pointing to primary hepatocellular injury. This is common in acute viral hepatitis, medication or toxin effects, and fatty liver related to metabolic syndrome. People may notice fatigue, right‑upper‑abdominal discomfort, dark urine, or jaundice. In teens and young adults with obesity, this low‑ratio pattern is frequent. Pregnancy doesn't meaningfully change the ratio's meaning, though enzyme levels may be slightly lower overall. Systemically, it signals strain on hepatic glucose handling, lipid packaging, bile acid flow, and urea formation.

When the ratio climbs above about 1.5–2, AST predominates. That pattern classically suggests alcohol‑related liver injury, where mitochondrial damage and lower ALT activity raise the ratio, and it also appears with advancing fibrosis or cirrhosis of any cause as ALT falls with reduced hepatocyte mass. A high ratio with normal or mildly elevated ALT can reflect muscle injury; accompanying muscle soreness or weakness and an elevated CK support that source. High ratios can also arise from extrahepatic sources—skeletal or cardiac muscle injury, vigorous exercise, or hemolysis—shifting interpretation beyond the liver. In older adults the ratio tends to rise with fibrosis; in pregnancy, markedly elevated AST with hypertension can occur in HELLP/preeclampsia.

What Can Throw Off a De Ritis Reading

Notes: Interpret the ratio alongside the absolute AST and ALT values. Hemolyzed samples, recent strenuous exercise, intramuscular injections, and many medications can skew results. Pregnancy generally lowers aminotransferases; lab methods and reference ranges vary.