What’s the correlation between AST, ALT, ALP and GGT?

  • ALT and AST are abundant liver enzymes.
  • AST is also present in heart, muscle.
  • ALP is present in nearly all tissues, primarily bone and liver.
  • GGT is abundant in liver, kidney, pancreas and intestine.

Normal levels:

ALT and AST normal ranges vary depending on lab, in general: ≤ 40 U/L.

Mild ALT and AST elevations:

(ALT and AST less than 5 times the upper limit of normal)

–> Should be rechecked before extensive work-up is undertaken.

  • Possible causes:
    • Chronic hepatitis C or B
    • Acute viral hepatitis
    • Nonalcoholic Fatty Liver Disease
    • Hemochromatosis (iron disorder)
    • Autoimmune hepatitis
    • Medications
    • Alcohol-related liver injury
    • Wilson’s disease

Moderately elevated ALT and AST

(ALT and AST 5-15 times the upper limit of normal)

–> Should be investigated without waiting to confirm the persistence of abnormal ALT.

  • Possible causes:
    • entire spectrum of liver diseases that may cause either mild or severe elevations.

Severe ALT and AST elevations: 

(ALT and AST greater than 15 times the ULN)

Suggest severe acute liver cell injury:

  • acute viral hepatitis
  • ischemic hepatitis or other vascular disorder
  • toxin-mediated hepatitis
  • acute autoimmune hepatitis

Elevated ALP and GGT:

  • Bile duct obstruction,
  • primary biliary cirrhosis,
  • primary sclerosing cholangitis,
  • benign recurrent cholestasis,
  • infiltrative disease of the liver (sarcoidosis, lymphoma, metastasic disease)

Isolated high ALP (extra-hepatic disease): 

  • bone disease,
  • pregnancy,
  • chronic renal failure,
  • lymphoma,
  • congestive heart failure.


  • Poor correlation between ALT and AST levels and hepatic fibrosis (=overly exuberant wound healing in which excessive connective tissue builds up in the liver).
  • Patients with cirrhosis may have normal or only mildly elevated ALT.
  • ALT and AST: increase with strenuous exercise and muscle injury.
  • Meals have no effect.
  • ALT is increased with higher BMI.
  • ALP levels increase with food intake, pregnancy and smoking.



The information on is NOT intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice.

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