Abnormal LFTs are extremely common in hospital.

Most are:

mild
incidental
non-urgent

But occasionally they signal:

obstruction
acute hepatitis
decompensated cirrhosis
liver failure

Your job is to:

Recognise the pattern
Decide if it’s dangerous
Act appropriately

Not memorise long lists of causes.

✅ First principle

Never read LFTs number by number.

Always ask:

What pattern is this?

Because management depends on the pattern, not the exact value.

There are only three patterns you need to recognise.

✅ Step 1 – Know what each test actually represents

Before interpreting, understand what they mean clinically.

ALT / AST → hepatocellular injury

Leak out when liver cells are damaged.

Think:
👉 inflammation or cell injury

Examples:

hepatitis
alcohol
fatty liver
drugs

ALP (± GGT) → cholestasis / obstruction

Raised when bile flow is blocked.

Think:
👉 bile duct problem

Examples:

gallstones
cholangitis
PSC/PBC
tumour

Bilirubin → excretion problem

Raised when:

obstruction
liver dysfunction
haemolysis

Think:
👉 jaundice severity

Albumin & INR → liver function (most important)

Reflect how well the liver is working.

Think:
👉 severity, not diagnosis

If abnormal → patient may be sick.

✅ Step 2 – Identify the pattern

This is the key step.

🟡 Hepatocellular pattern (ALT predominant)

Labs:

ALT/AST ↑↑
ALP normal or mild

Think:

Liver inflammation/injury

Common real-life causes:

MASLD
alcohol
viral hepatitis
drugs (antibiotics, statins, paracetamol)
autoimmune hepatitis
ischaemic hepatitis

What to do:

👉 blood tests + history
(not urgent imaging usually)

🟢 Cholestatic pattern (ALP predominant)

Labs:

ALP ↑↑
ALT mild

Think:

Bile duct obstruction

Common causes:

gallstones
cholangitis
malignancy
PSC/PBC
drug cholestasis

What to do:

👉 ultrasound first

Imaging is more important than blood tests here.

🔴 Synthetic dysfunction pattern

Labs:

Low albumin
High INR
± bilirubin

Think:

Liver failing

Causes:

cirrhosis
acute liver failure
severe hepatitis
sepsis

What to do:

👉 escalate early

This is the dangerous group.

✅ Step 3 – Add the clinical story

LFTs never interpreted in isolation.

Always combine with:

symptoms
observations
alcohol history
medications
metabolic risk
infection risk

Pattern + history = diagnosis

✅ Practical ward examples (how to think fast)

Scenario 1

ALT 550, ALP 120
→ hepatocellular
→ think hepatitis/drug/alcohol

Scenario 2

ALP 600, jaundice, fever
→ cholestatic
→ think cholangitis
→ urgent imaging + antibiotics

Scenario 3

AST > ALT (2:1), alcohol history
→ alcohol-related

Scenario 4

Low albumin, INR 2.0, ascites
→ decompensated cirrhosis
→ escalate

Scenario 5

Mild ALT 70 in obese diabetic
→ likely MASLD
→ outpatient management

✅ Red flags you must not miss

Escalate urgently if:

confusion / encephalopathy
INR rising
jaundice + sepsis
hypotension
severe pain
very high ALT (>1000)
known cirrhosis deteriorating

These are not routine LFT abnormalities.

❌ Common junior mistakes

Reading numbers individually
Over-investigating mild ALT rises
Missing synthetic failure
Forgetting medication history
Not imaging cholestasis
Referring everyone to gastro

Most abnormal LFTs are benign.

A few are dangerous.

Learn to tell the difference.

✅ Simple ward algorithm

When you see abnormal LFTs:

Is the patient sick?
ALT or ALP predominant?
Any synthetic dysfunction?
Blood tests or imaging?
Urgent or routine referral?

That’s it.

✅ Take-home concept

ALT = inflammation
ALP = obstruction
INR/albumin = severity

If you recognise those three ideas, you can interpret 90% of LFTs safely.