Integrated LFT Interpretation
Why no single marker tells the whole story
Liver enzyme interpretation should never rely on a single parameter. Combining AST, ALT, GGT, ALP, bilirubin and the R-value differentiates hepatocellular injury, cholestatic disease, mixed injury, alcohol-related disease, MASLD, muscle-related AST elevation, bone-related ALP elevation, and rarer disorders such as Wilson's disease.
AST/ALT Ratio — Quick Reference
| Ratio | Interpretation | Common Causes |
|---|---|---|
| <1.0 | ALT higher than AST | Viral hepatitis, MASLD/NAFLD, DILI, autoimmune hepatitis |
| ≈1.0 | AST ≈ ALT | Acute viral hepatitis, early inflammation, mixed injury |
| >1.0 | AST exceeds ALT | Fibrosis, cirrhosis, chronic liver disease |
| >2.0 | AST >2× ALT | Strongly suggests alcoholic liver disease / alcoholic hepatitis |
Why AST and ALT Behave Differently
ALT (also SGPT)
Primarily found inside hepatocytes. The most liver-specific enzyme — a better marker of hepatocellular injury than AST. Older lab reports and some Malaysian government labs still label this as SGPT (Serum Glutamic-Pyruvic Transaminase) — same test, same units.
AST (also SGOT)
Present in liver, skeletal muscle, cardiac muscle, kidney, brain, and red blood cells. Can rise from heavy exercise, muscle injury, trauma, myocardial infarction, or rhabdomyolysis. Older reports label this as SGOT (Serum Glutamic-Oxaloacetic Transaminase).
Clinical pearl
An isolated AST elevation should never automatically be interpreted as liver disease. Check GGT — if normal, consider a non-hepatic source.
GGT — The Missing Piece
What it confirms
GGT (Gamma-Glutamyl Transferase) reflects biliary epithelial injury, enzyme induction, and chronic alcohol exposure. Adding GGT confirms whether abnormal AST/ALP truly originate from the liver.
Without GGT
An elevated AST may originate from muscle or heart — easy to misattribute to liver disease.
With elevated GGT
Liver origin becomes much more likely, particularly when paired with a raised ALP (cholestasis) or raised AST>ALT (alcohol).
ALP — Locating the Source
Produced by
Liver (bile ducts), bone, placenta, and intestine (minor). Because ALP is not liver-specific, an isolated elevation requires further evaluation.
High ALP + High GGT
Strongly suggests cholestatic liver disease or biliary obstruction — choledocholithiasis, primary biliary cholangitis, primary sclerosing cholangitis, malignant biliary obstruction.
High ALP + Normal GGT
Suggests a non-hepatic cause — bone healing, vitamin D deficiency, Paget disease, hyperparathyroidism, osteomalacia, adolescent growth, or bone metastases.
The R-Value — Official Classification
Formula
R = (ALT ÷ ALT ULN) ÷ (ALP ÷ ALP ULN)
| R-value | Pattern | Common Causes |
|---|---|---|
| >5 | Hepatocellular | Viral hepatitis, DILI, ischaemic hepatitis, autoimmune hepatitis |
| 2–5 | Mixed | Mixed DILI, acute cholecystitis, autoimmune overlap |
| <2 | Cholestatic | Choledocholithiasis, PBC, PSC, malignant biliary obstruction |
Wilson's Disease Marker (Adjunctive Only)
Pattern
In acute liver failure, an ALP/Total Bilirubin ratio <4 combined with an AST/ALT ratio >2.2 is highly suggestive of Wilson's disease — especially in younger patients.
Caveat
This is an adjunctive clue only. Confirm with ceruloplasmin, serum copper, urinary copper excretion, and slit-lamp examination for Kayser-Fleischer rings.
Important Clinical Caveats
Always correlate with
Clinical history, alcohol intake, medication history, viral hepatitis risk factors, metabolic syndrome, BMI, and physical examination.
Review alongside
AST, ALT, ALP, GGT, bilirubin, albumin, INR/PT, platelet count, CBC, and creatine kinase when muscle injury is suspected.
Ready to interpret a patient's results? Go to the Interpreter tab to enter values manually or upload a photo of the lab report.
LFT Interpreter
Upload a report to auto-fill, or enter everything manually below
Step 1 — Upload Lab Report (Optional)
Click to upload or drag a photo of the lab report
JPG, PNG. Best results with a clear, well-lit, non-tilted photo. Recognizes both current (ALT/AST) and older (SGPT/SGOT) naming. Will attempt to auto-fill patient name, age, sex, lab values, and reference ranges below.
Every auto-filled field — including reference ranges — must be checked below before calculating. OCR can misread numbers, and a wrong reference range will skew every downstream calculation. Always verify against the original report.
Step 2 — Patient Information
Step 3 — Clinical History
Drug History
Symptoms
Step 4 — Laboratory Values & Reference Ranges
FIB-4 and APRI fibrosis scores are optional extras. The interpreter itself only needs ALT, AST, ALP, GGT, and Total Bilirubin — everything else below, including Age and Platelets, is optional. If you happen to have Age (Step 2, Patient Information) and Platelets on hand, entering them will additionally calculate FIB-4/APRI fibrosis scores. If not, that's fine — the rest of the interpretation runs normally without them.
| Marker | Result | Unit | Ref. Low | Ref. High |
|---|
* Required: ALT, AST, ALP, GGT, Total Bilirubin. Reference ranges are pre-filled defaults — edit to match your lab's report. All fields are directly editable whether entered manually or extracted from a photo.
Step 5 — Previous Results (Optional — For Trend Comparison)
If you have a previous LFT result in hand for this patient, entering it here lets the interpreter compare trend direction (rising/falling/stable) against today's values — this can meaningfully strengthen or weaken several differentials (e.g. a rapid fall after a cardiac event supports ischaemic hepatitis; a stable mild rise over time supports a chronic rather than acute process). Entirely optional — leave blank if you don't have a previous result on hand.
Click to upload the previous report photo
Extracts into the "Previous Result" column below — separate from today's photo upload above. All fields remain editable for verification.
| Marker | Previous Result | Unit |
|---|---|---|
| ALT (SGPT) | U/L | |
| AST (SGOT) | U/L | |
| GGT | U/L | |
| ALP | U/L | |
| Bilirubin, Total | umol/L |
Enter values in the same units shown (U/L for enzymes, umol/L for bilirubin) — if your previous report used different units, convert before entering. Fill in only the markers you have; partial entry is fine.
Report Reader
Upload any lab report photo or PDF — get the whole report back as clean, copyable text
Upload Report
Click to upload a photo or PDF of any lab report
Not limited to liver function tests — full blood count, renal profile, lipid panel, any report. Transcribes every test result with units, reference ranges, and abnormal flags, grouped by panel, ready to copy elsewhere.
Fibrosis Risk Scores
FIB-4 and APRI — calculated automatically in the Interpreter tab
FIB-4 and APRI are calculated automatically whenever Age, AST, ALT and Platelet count are entered in the Interpreter tab. This tab is a reference for how to interpret them.
FIB-4 Index
Formula
FIB-4 = (Age × AST) ÷ (Platelets × √ALT)
| Age | Low risk | Intermediate | High risk |
|---|---|---|---|
| <65 years | <1.30 | 1.30–2.67 | >2.67 |
| ≥65 years | <2.00 | 2.00–2.67 | >2.67 |
Note
The age-adjusted cutoff (<2.0 vs <1.3) in patients ≥65 years reduces false-positive results, since FIB-4 tends to overestimate fibrosis risk in older adults if the standard cutoff is used.
APRI (AST to Platelet Ratio Index)
Formula
APRI = [(AST ÷ AST ULN) × 100] ÷ Platelets (×10⁹/L)
| APRI | Interpretation |
|---|---|
| <0.5 | Low probability of significant fibrosis |
| 0.5–1.5 | Indeterminate |
| >1.5 | High probability of significant fibrosis / cirrhosis |
Interpreting Fibrosis Scores
Both low
Significant fibrosis unlikely. Routine follow-up appropriate; reassess risk factors periodically.
Either high or both intermediate
Consider referral for FibroScan (transient elastography) or hepatology assessment. Non-invasive scores are screening tools, not a substitute for elastography or biopsy when the diagnosis is unclear.
Limitations
FIB-4 and APRI were validated primarily in viral hepatitis (especially hepatitis C) cohorts. Performance in MASLD and other aetiologies is reasonable but less extensively validated — interpret with clinical context.
Reference Tables
Pattern lookup, default ranges, and practical algorithm
Photo-Upload Usage (All Doctors)
Total clinic-wide count of successful lab report extractions
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Default Reference Ranges (Adult) — Editable in Interpreter
| Marker | Default Range | Unit |
|---|---|---|
| ALT | M: 7–41 | F: 7–33 | U/L |
| AST | 8–48 | U/L |
| GGT | M: <60 | F: <40 | U/L |
| ALP | 30–130 | U/L |
| Bilirubin (Total) | 3–21 | µmol/L |
| Bilirubin (Direct) | 0–5 | µmol/L |
| Albumin | 35–50 | g/L |
| Total Protein | 60–80 | g/L |
| INR | 0.8–1.2 | ratio |
| Platelets | 150–400 | ×10⁹/L |
| CK | 30–200 | U/L |
| Creatinine | 60–110 | µmol/L |
These are general adult defaults only — always check and adjust to your specific laboratory's printed reference range, which can vary by analyser and method.
AST/ALT + GGT Combined Lookup
| AST/ALT | GGT | Most Likely |
|---|---|---|
| <1 | Normal / mildly elevated | MASLD/NAFLD, viral hepatitis |
| ≈1 | Variable | Acute hepatitis, early inflammation |
| >1 | Elevated | Fibrosis, chronic liver disease |
| >2 | Markedly elevated (6-8× ULN) | Alcoholic liver disease |
| High AST | Normal | Muscle injury, exercise, rhabdomyolysis |
| — | High ALP + High GGT | Cholestasis / biliary obstruction |
Practical Diagnostic Algorithm
Step 1
Evaluate AST, ALT, ALP, GGT, bilirubin
Step 2
Calculate AST/ALT ratio and R-value
Step 3
Interpret GGT — confirms/refutes hepatobiliary origin
Step 4
Assess ALP source: high ALP + high GGT → hepatobiliary; high ALP + normal GGT → bone/non-hepatic
Step 5
Assess bilirubin (total and direct fraction)
Step 6
Correlate with alcohol use, medications, viral hepatitis risk, metabolic syndrome, muscle injury, and imaging if indicated
Step 7
Determine injury pattern: hepatocellular, cholestatic, mixed, alcohol-related, metabolic, muscle-derived, bone-derived, or Wilson's disease (when appropriate)
References: AASLD Practice Guidance · EASL Clinical Practice Guidelines · ACG Clinical Guideline: Evaluation of Abnormal Liver Chemistries · NICE NAFLD Guidelines · Sterling et al. (FIB-4, Hepatology 2006) · Wai et al. (APRI, Hepatology 2003)