Understanding Your Liver Function Test (LFT): What Every Number Means

You went for your annual health checkup, got an LFT done, and came back with a sheet full of abbreviations — ALT, AST, ALP, GGT, bilirubin, albumin. One of them is printed in red.

Now what?

This guide walks through every parameter in a standard Liver Function Test, what it actually measures, and what an out-of-range value typically means. No medical degree needed.

Why Is an LFT Ordered?

Your liver is one of the hardest-working organs in your body. It filters your blood, produces bile for digestion, stores energy, makes proteins that help your blood clot, and breaks down medications and alcohol.

An LFT (also called a Liver Function Panel or LFP) is a group of blood tests that together give your doctor a picture of how well your liver is functioning. It's routinely included in annual health checkups, and is also ordered when symptoms like fatigue, yellowing of skin, or abdominal pain are present.

The Parameters — One by One

ALT (SGPT) — Alanine Aminotransferase

Normal range: 7–56 U/L (men tend to run slightly higher than women)

ALT is the most liver-specific marker in this panel. It's an enzyme that lives mostly inside liver cells. When liver cells are damaged or inflamed, they release ALT into the bloodstream — so a raised ALT is often the first signal that something is stressing your liver.

Mildly elevated ALT (up to 2–3× the upper limit) is common and can be caused by fatty liver, recent heavy exercise, certain medications, or even a recent viral infection. A significantly elevated ALT (5× or more) warrants prompt follow-up.

AST (SGOT) — Aspartate Aminotransferase

Normal range: 10–40 U/L

AST is similar to ALT but less liver-specific — it's also found in heart muscle, skeletal muscle, and red blood cells. That's why AST alone doesn't tell you much; it's the ratio of AST to ALT that matters.

AST/ALT ratio > 2:1 often points to alcohol-related liver damage
AST/ALT ratio < 1 (ALT higher than AST) is more typical of non-alcoholic fatty liver disease (NAFLD)

If only your AST is elevated and your ALT is normal, your doctor may look at your heart and muscle enzymes too.

ALP — Alkaline Phosphatase

Normal range: 44–147 U/L (adults); higher ranges are normal in children and pregnant women

ALP is an enzyme found in the liver, bile ducts, and bones. An elevated ALP can point to a bile duct blockage (a condition where bile can't drain properly from the liver) — or to bone conditions. Context matters here.

If your ALP is high but your ALT and AST are normal, your doctor may check GGT — a liver/biliary-specific enzyme — to figure out whether the liver or bones are the source. If GGT is also high, the liver/bile duct is the likely source; if GGT is normal, the elevated ALP is more likely coming from bone.

GGT — Gamma-Glutamyl Transferase

Normal range: Less than 55 U/L (men), less than 38 U/L (women)

GGT is particularly sensitive to alcohol and to bile duct problems. It's often checked alongside ALP — if both are elevated, the liver/bile duct is the likely source. GGT alone being elevated is frequently linked to alcohol consumption, fatty liver, or certain medications.

It's worth knowing that GGT is very sensitive — even modest regular alcohol intake can push it above normal.

Total Bilirubin

Normal range: 0.2–1.2 mg/dL

Bilirubin is a yellow-orange pigment produced when old red blood cells are broken down. Your liver processes this bilirubin and excretes it through bile. When the liver is damaged, or when the bile duct is blocked, bilirubin builds up in the blood — causing the yellowish tint to skin and eyes you may recognise as jaundice.

Total bilirubin is split into two sub-types:

Direct (Conjugated) Bilirubin — Normal: 0.0–0.3 mg/dL This is bilirubin that has already been processed by the liver. High direct bilirubin usually points to a problem with bile drainage (blockage in the bile duct or a liver disease).

Indirect (Unconjugated) Bilirubin — Normal: 0.2–0.9 mg/dL This is bilirubin that hasn't been processed yet. High indirect bilirubin is more often linked to conditions where red blood cells are being broken down too quickly (haemolytic anaemia) rather than a liver problem itself.

Total Protein

Normal range: 6.3–8.2 g/dL

Your liver manufactures most of your blood proteins. Total protein measures the combined amount of two main proteins — albumin and globulin — in your blood. Very low total protein can suggest the liver isn't producing proteins efficiently. Very high levels can indicate chronic infection or immune conditions.

Albumin

Normal range: 3.5–5.0 g/dL

Albumin is the most abundant protein in your blood, made almost entirely by the liver. It carries nutrients, hormones, and medications through your bloodstream and helps maintain fluid balance (preventing fluid from leaking out of blood vessels into tissues).

Low albumin is a meaningful signal — it suggests the liver has been under prolonged stress and its protein-making capacity is reduced. This is why albumin is sometimes called a marker of chronic liver function rather than acute damage.

Globulin and A/G Ratio

Normal globulin range: 2.0–3.5 g/dL
Normal A/G ratio: 1.2–1.8

Globulins include immune proteins (antibodies) made by your immune system, not the liver. The A/G ratio (Albumin divided by Globulin) is a quick check of the balance between these two protein types. A reversed or low A/G ratio (below 1.0) can indicate liver disease or certain immune conditions.

A Quick Reference Table

| Parameter | Normal Range | What It Measures | |---|---|---| | ALT (SGPT) | 7–56 U/L | Liver cell damage | | AST (SGOT) | 10–40 U/L | Liver + muscle/heart damage | | ALP | 44–147 U/L | Bile duct / bone | | GGT | <55 (M), <38 (F) U/L | Bile duct, alcohol effect | | Total Bilirubin | 0.2–1.2 mg/dL | Liver processing of red cell waste | | Direct Bilirubin | 0.0–0.3 mg/dL | Bile drainage | | Indirect Bilirubin | 0.2–0.9 mg/dL | Red cell breakdown | | Albumin | 3.5–5.0 g/dL | Chronic liver function | | Total Protein | 6.3–8.2 g/dL | Overall protein production | | A/G Ratio | 1.2–1.8 | Protein balance |

Common Reasons for Mildly Elevated Values

Before worrying, it's worth knowing that LFT values can shift for reasons that have nothing to do with serious liver disease:

Fatty liver (NAFLD) — The most common cause of mild ALT/AST elevation in India. Closely linked to excess weight, diabetes, and high triglycerides. Very manageable with lifestyle changes.
Alcohol — Even moderate regular drinking raises GGT and can elevate ALT.
Medications — Paracetamol (paracetamol-based cold medicines), statins, antifungals, antitubercular drugs, and many Ayurvedic/herbal supplements can stress the liver.
Recent intense exercise — Can raise AST and ALT temporarily (from muscle, not liver).
Viral infections — Even a common fever can cause transient elevation of liver enzymes.
Thyroid conditions — Hypothyroidism is sometimes linked to elevated ALP and ALT.

What to Do If Something Is Flagged

A single out-of-range value, especially a mild one, rarely means something serious. What matters most is:

How far above normal? A value 1.5× the upper limit is very different from 5× the upper limit.
Which combination of values is elevated? ALT + AST together tells a different story from ALP + GGT alone.
Do you have symptoms? Fatigue, yellow eyes, dark urine, or pale stools alongside elevated values need prompt attention.
What's your baseline? Some people naturally run at the higher end of normal their whole lives.

The best next step is always to bring your report to your doctor and ask specifically: "Which of these values should I be monitoring? What's causing this, and what should I do?"

Questions to Ask Your Doctor

If your LFT has any flagged values, consider asking:

Is this elevation mild, moderate, or significant — and what's the likely cause given my lifestyle?
Should I repeat this test in 4–8 weeks to see if it resolves on its own?
Do I need an ultrasound of my liver?
Are any of my current medications (including supplements) contributing to this?
What lifestyle changes — diet, alcohol, exercise — would bring these numbers down?

The Takeaway

Your LFT is a panel, not a single test — the values only make full sense together. Mild elevations are common and often reversible. What matters is understanding which markers are affected, by how much, and why — so you can have a focused conversation with your doctor rather than just staring at a red number in confusion.

Be the first to try ReportSense.
When ReportSense launches, it will read your full LFT report, explain every value in plain language, flag the ones that need attention, and give you specific questions tailored to your exact results — before your next appointment. Join the waitlist and get early access.

Medical disclaimer: This article is for educational purposes only. It does not constitute medical advice, and no information here should be used to self-diagnose or self-treat. Always consult a qualified doctor for interpretation of your test results and any medical decisions.