Liver Health Journey: From ALT to MRI

Your blood test came back with raised ALT. Now what? This guide walks you through the entire liver health pathway — from understanding what that first abnormal result means, through the investigation process, to what a liver MRI can tell you that blood tests can't. Think of it as a step-by-step map from "your ALT is raised" to "here's exactly what's going on with your liver."

Step 1: The Initial Blood Test

Most liver investigations start the same way — a routine blood test flags raised ALT. Here's how to read the initial results:

The Key Liver Markers

Reading the Pattern

• ALT raised, AST normal or lower than ALT: Most common pattern. Usually NAFLD (non-alcoholic fatty liver disease) or medication effect.
• AST higher than ALT (ratio >2:1): Suggests alcohol-related liver damage.
• GGT + ALP raised, ALT normal: Points to bile duct obstruction — consider MRCP imaging.
• Everything raised: Significant liver disease — needs prompt investigation.
• Low albumin: Suggests chronic liver damage (the liver is struggling to make proteins).

Step 2: Rule Out Common Causes

Before jumping to imaging, your GP should check for reversible causes:

• Medications: Statins, paracetamol (chronic use), antibiotics, NSAIDs — can all raise ALT. Sometimes stopping the medication normalises it.
• Alcohol: Even moderate drinking can raise GGT and ALT. A period of abstinence (4–6 weeks) followed by a recheck can be diagnostic.
• Weight/BMI: NAFLD is the most common cause of raised ALT in the UK, affecting roughly 25–30% of adults. It's strongly linked to being overweight.
• Viral hepatitis: Hepatitis B and C blood tests should be checked if not done already.
• Autoimmune markers: ANA, smooth muscle antibodies, immunoglobulins — checking for autoimmune hepatitis.

Step 3: When to Image the Liver

Imaging is the right next step when:

• ALT remains elevated after addressing reversible causes (3–6 months of lifestyle changes)
• ALT is significantly raised (>2–3x upper limit) from the start
• You have symptoms: fatigue, right-upper-quadrant abdominal pain, jaundice, unexplained weight loss
• Other blood markers are abnormal (raised bilirubin, low albumin, raised GGT/ALP)
• You need to quantify fatty liver — MRI can give an exact fat percentage

Ultrasound First

The usual first-line imaging is a liver ultrasound. It can detect:

• Fatty liver (bright/echogenic liver on ultrasound)
• Gallstones
• Obvious masses or cysts
• Bile duct dilation

But ultrasound has significant limitations: it's operator-dependent, can't quantify fat precisely, struggles with deep lesions in larger patients, and can't characterise lesions as well as MRI.

Step 4: The Liver MRI

Liver MRI is indicated when ultrasound is inconclusive, when precise fat or iron quantification is needed, or when a lesion needs characterisation. Here's what MRI adds:

Step 5: Understanding Your MRI Results

Your liver MRI report will include:

• Liver size and shape: Enlarged (hepatomegaly) or normal.
• Fat content: If PDFF was performed — expressed as a percentage. Normal <5%. Mild steatosis 5–17%. Moderate 17–22%. Severe >22%.
• Iron content: Normal or overloaded (if measured).
• Any focal lesions: Size, location, and characterisation. The radiologist will classify them (cyst, haemangioma, focal nodular hyperplasia, adenoma, or suspicious for malignancy).
• Bile ducts: Normal calibre or dilated. Any stones or strictures visible.
• Surrounding structures: Spleen size, portal vein patency, ascites (fluid).

Step 6: What Happens Next

• NAFLD with mild fat (<17%) + no fibrosis: Lifestyle changes — weight loss, exercise, reduce alcohol. Repeat bloods and MRI in 12 months to track progress.
• Significant fatty liver (>17%) or fibrosis: Referral to hepatology. More aggressive lifestyle intervention. Possible medication.
• Benign lesion (cyst/haemangioma): Usually no treatment needed. Monitoring if large.
• Suspicious lesion: Urgent hepatology referral. May need biopsy or further imaging.
• Iron overload: Genetic testing for haemochromatosis. Treatment: venesection (regular blood removal).

Related Guides

• Elevated Liver Enzymes → Liver MRI — Detailed enzyme guide
• Iron Deficiency → Further Investigation
• When Blood Tests Suggest You Need a Scan
• MRI vs CT vs Ultrasound
• MRI Scan Cost by Body Part