Abnormal Liver Tests: What High ALT, AST, or Bilirubin Means

Liver tests are part of routine blood work, so many people learn their numbers are "a little high" without any symptoms. Abnormal results are common and often mild, but they are worth understanding, because some causes can lead to liver scarring over time.

What the tests measure

• ALT and AST: enzymes released when liver cells are irritated or injured
• Alkaline phosphatase (ALP) and GGT: often high when bile flow is slowed or the bile ducts are affected
• Bilirubin: a yellow pigment; high levels can cause jaundice
• Albumin, INR, and platelets: reflect how well the liver is working and whether there may be advanced scarring

Common causes

• Fatty liver disease (MASLD), the most common cause
• Alcohol
• Medicines, herbal products, and supplements
• Hepatitis B and hepatitis C
• Autoimmune and cholestatic liver diseases
• Gallstones blocking the bile duct
• Inherited conditions such as hemochromatosis (iron overload) and Wilson disease
• Gilbert syndrome, a harmless cause of mildly high bilirubin

Next steps

• Repeat testing and a review of alcohol, medicines, and supplements
• Blood tests for viral hepatitis, iron, and autoimmune markers
• An abdominal ultrasound
• Liver elastography (FibroScan) in our office to measure scarring

Bring a list of every medicine and supplement you take, including herbal products, to your visit.

Make an appointment

Our gastroenterologists in Temple City care for patients from Arcadia, San Gabriel, Pasadena, Monrovia, Monterey Park, and across the San Gabriel Valley. We accept most PPO plans (see accepted insurances), and our doctors speak English, Vietnamese, and Mandarin. Schedule an appointment or call 626-898-4560.

This article is for general education and is not a substitute for medical advice. Talk with your doctor about your own health.