approach to elevated liver enzymes
Contents
Classify the pattern first: hepatocellular (ALT/AST dominant) vs cholestatic (ALP/GGT dominant) vs mixed. The magnitude of transaminase elevation narrows the differential substantially. Cholestatic patterns split by whether bile ducts are dilated on imaging. A systematic first-pass panel catches the majority of causes without shotgun testing.
- transaminases >1000 U/L → acute liver injury (toxin, ischaemia, acute viral) — identify cause and trend within hours
- rising bilirubin with falling albumin or rising INR → synthetic failure — hepatology urgently
- encephalopathy → this is acute liver failure, not just “elevated enzymes”
- new ascites or signs of portal hypertension
pattern recognition
hepatocellular (ALT/AST dominant)
| magnitude | differential |
|---|---|
| >1000 U/L (“thousands”) | toxins/drugs (acetaminophen, cocaine), acute viral hepatitis (A, B, D, E), ischaemic hepatitis (shock liver), Budd-Chiari syndrome, acute biliary obstruction (<24 h), autoimmune hepatitis, fulminant Wilson’s disease |
| 100–1000 U/L (“hundreds”) | chronic viral (HBV, HCV, EBV, CMV), congestive hepatopathy, alcohol-associated hepatitis (AST > ALT, ratio ≥1.5–2:1, values <400 U/L) |
| <100 U/L | MASLD/MetALD, celiac disease, hereditary hemochromatosis, Wilson’s disease, alpha-1 antitrypsin deficiency, hypothyroidism |
AST > ALT with ratio ≥2:1 and both values <400 U/L → alcohol-associated liver disease until proven otherwise. The ratio reflects mitochondrial injury from alcohol plus pyridoxine deficiency lowering ALT. An AST:ALT ratio >1 in someone with chronic hepatitis also raises concern for advancing fibrosis/cirrhosis.
cholestatic (ALP/GGT dominant)
Extrahepatic (bile duct dilatation on US/MRCP):
- painful → choledocholithiasis
- painless → strictures (PSC, benign, IgG4-related disease) or malignancy (cholangiocarcinoma, pancreatic head, ampullary)
Intrahepatic (no duct dilatation):
- drugs (antibiotics, TPN, oestrogens, methotrexate)
- PBC
- sepsis, cholestasis of pregnancy
- infiltrative (sarcoidosis, amyloid, lymphoma)
- metastatic disease
When cholestatic imaging is needed, use US first then MRCP. ERCP carries procedural risk (pancreatitis, perforation) and is reserved for therapeutic intervention — stone extraction, stent placement, stricture dilation.
isolated elevations
- Isolated ALP elevation → confirm hepatic origin with GGT (if GGT normal, ALP is likely bone). In pregnancy, placental ALP rises physiologically.
- Isolated GGT elevation → non-specific; alcohol, drugs, obesity, diabetes. Not useful in isolation as a screening test.
- Isolated AST elevation → consider cardiac or skeletal muscle source (check CK). Macro-AST is a rare benign cause of persistent elevation.
first-pass workup
Order based on pattern, not as a reflex panel:
| hepatocellular | cholestatic | both patterns |
|---|---|---|
| hepatitis serologies (HAV IgM, HBsAg, anti-HBc, anti-HCV) | abdominal US (duct dilatation?) | CBC, INR, albumin, bilirubin |
| ferritin + transferrin saturation | AMA (if intrahepatic pattern) | lipase |
| ceruloplasmin (age <40) | MRCP (if US equivocal or high suspicion for stones/stricture) | pregnancy test (reproductive age) |
| ANA, ASMA, IgG (AIH screen) | IgG4 (if stricture on imaging) | drug/supplement review |
| alpha-1 antitrypsin level | — | abdominal US |
| tTG-IgA + total IgA (celiac) | — | — |
Medications, supplements, and herbal products are among the most common causes of elevated liver enzymes across all patterns. Statins cause mild transaminase elevation in up to 3% but rarely cause clinically significant liver injury — statin hepatotoxicity is massively over-diagnosed and should not prompt discontinuation unless ALT exceeds 5× ULN with symptoms.
traps
- Assuming elevated ferritin = haemochromatosis — ferritin is an acute-phase reactant. Transferrin saturation <45% with normal ferritin rules out hereditary hemochromatosis with 97% NPV. No HFE testing needed.
- Stopping statins for mild ALT elevation — check ALT was not already elevated before starting. Baseline MASLD is more common than statin hepatotoxicity.
- Missing celiac disease — causes unexplained mild transaminase elevation in up to 9% of cases. Screen with tTG-IgA + total serum IgA.
- Ordering ERCP for diagnosis — MRCP is the diagnostic study for biliary obstruction; ERCP is interventional.
- Ignoring alcohol — patients underreport; AST:ALT ratio and GGT help. AUDIT-C is a reasonable screening tool.
related: viral hepatitis · alcohol-associated hepatitis · MASLD · hereditary hemochromatosis · autoimmune and metabolic liver diseases · cirrhosis · celiac disease