Liver Function Tests: What Your LFT Really Means

The Organ That Never Complains — Until It's Too Late

In India, non-alcoholic fatty liver disease (NAFLD) affects 30-40% of urban adults. Most have no idea. You don't need to drink alcohol to damage your liver — sedentary work, stress eating, and genetics can do it just as effectively.

Your liver is stoic. It doesn't announce its distress with pain or obvious symptoms. You could have elevated enzymes for years and feel perfectly fine. By the time symptoms appear, the damage can be significant.

This is why understanding liver function tests — those cryptic abbreviations like ALT, AST, GGT — matters so much. They're your liver's only way of sending a distress signal.

Your Body's Silent Chemical Factory

Before diving into the tests, let's appreciate what the liver does. This 1.5 kg organ tucked under the right ribs performs over 500 functions every moment:

• Detoxification: Processing everything you eat, drink, breathe, and absorb through your skin — medications, pollutants, alcohol, metabolic waste
• Metabolism: Converting food into energy, regulating blood sugar, processing fats
• Protein synthesis: Making albumin (keeps fluid in blood vessels), clotting factors (so you don't bleed), and hundreds of other proteins
• Bile production: Essential for digesting fats and absorbing fat-soluble vitamins (A, D, E, K)
• Storage: Storing iron, vitamins, glycogen for when needed
• Immune function: Filtering bacteria and old blood cells

The liver regenerates itself — you can lose 75% of it and it will grow back. This remarkable resilience is also its curse. It compensates, adapts, and soldiers on without complaint until it can't anymore.

The Liver Function Test Panel — Decoded

When you get an "LFT" or "liver profile," here's what each component actually measures:

The Enzymes: Leak Detectors

Liver enzymes aren't measuring liver "function" per se — they're measuring liver cell damage. When liver cells are injured, these enzymes leak into the bloodstream. Think of them as alarm bells.

Enzyme	Normal Range	Where It Comes From	What Elevation Suggests
ALT (SGPT)	7-56 U/L	Primarily liver	Liver-specific damage
AST (SGOT)	10-40 U/L	Liver, heart, muscle	Liver or other tissue injury
ALP	44-147 U/L	Liver, bone, intestine	Bile duct obstruction, bone disease
GGT	M: 8-61, F: 5-36 U/L	Liver, bile ducts	Bile duct disease, alcohol use

The Function Markers: How Well Is the Liver Working?

These actually measure the liver's ability to do its job:

Marker	Normal Range	What It Measures
Bilirubin (Total)	0.1-1.2 mg/dL	Bile processing (yellowing if elevated)
Albumin	3.5-5.0 g/dL	Protein synthesis ability
Total Protein	6.0-8.3 g/dL	Overall protein status
PT/INR	PT: 11-13.5 sec	Clotting factor production

ALT and AST: The Critical Ratio

These two enzymes tell a story, especially when looked at together.

ALT (SGPT) — The Liver Detective

ALT is found almost exclusively in liver cells. When ALT is elevated, the liver is almost certainly involved.

ALT Level	Interpretation	Common Causes
Below 40 U/L	Normal	Healthy liver
40-120 U/L	Mild elevation	Fatty liver, medications, early disease
120-300 U/L	Moderate elevation	Chronic hepatitis, ongoing liver injury
Above 300 U/L	Significant elevation	Acute hepatitis, severe toxicity
Above 1000 U/L	Severe	Acute viral hepatitis, drug-induced injury, ischemia

AST (SGOT) — The Multi-Organ Marker

AST is less specific — it's also present in heart and skeletal muscle. An isolated AST elevation without ALT elevation might mean:

• Heart attack (check cardiac enzymes)
• Muscle injury or intense exercise
• Medication effects

The AST/ALT Ratio — A Diagnostic Clue

The Fatty Liver Epidemic

Consider Ananya, 28, a software engineer. BMI of 24 — perfectly normal weight. Her ALT was 52 U/L. Mildly elevated. Her AST was 38 U/L. Normal. Ultrasound showed Grade 1 fatty liver.

"But I'm not overweight. I barely eat."

That was part of the problem. Ananya survived on coffee, skipped breakfast, had a late lunch at 3 pm (usually Maggi or biscuits from the office pantry), and ate a heavy dinner at 10 pm before collapsing into bed. Her diet was low in protein, high in refined carbs, and her eating pattern was wreaking havoc on her metabolism.

This is the face of modern fatty liver — often young, often normal weight, often vegetarian, almost always unaware.

Non-Alcoholic Fatty Liver Disease (NAFLD)

NAFLD is now the most common liver disease worldwide. In India, it affects:

• 30-40% of urban adults
• Up to 70% of those with diabetes
• Up to 90% of those with obesity

NAFLD progresses in stages:

Stage	What It Means	Reversibility
Simple Steatosis	Fat accumulation only	Fully reversible
NASH (Steatohepatitis)	Fat + inflammation	Reversible with effort
Fibrosis	Scarring begins	Partially reversible
Cirrhosis	Severe scarring	Irreversible (damage permanent)

The tragedy? NAFLD is often asymptomatic until cirrhosis develops. The liver doesn't hurt. There's no jaundice. Just slowly rising enzymes — or sometimes, even normal enzymes despite progressive disease.

Beyond the Numbers: Pattern Recognition

Experienced clinicians look for patterns in liver test results:

Pattern 1: Hepatocellular (Liver Cell Damage)

ALT and AST elevated, ALP and bilirubin relatively normal

Think: Fatty liver, viral hepatitis, drug toxicity, autoimmune hepatitis

Pattern 2: Cholestatic (Bile Flow Problem)

ALP and bilirubin elevated, ALT and AST mildly elevated or normal

Think: Bile duct obstruction (stones, tumors), primary biliary cholangitis

Pattern 3: Infiltrative

ALP elevated out of proportion, other markers relatively normal

Think: Liver tumors, granulomatous disease, metastatic cancer

Pattern 4: Synthetic Dysfunction

Low albumin, prolonged PT/INR, elevated bilirubin

Think: Advanced liver disease, cirrhosis — the liver can't do its job

GGT: The Alcohol Marker (But Not Only Alcohol)

GGT is often elevated with alcohol use, which is why it's sometimes called the "drinking enzyme." But this oversimplifies things.

GGT can be elevated in:

• Alcohol use (even moderate amounts)
• Fatty liver (with or without alcohol)
• Bile duct obstruction
• Medications (phenytoin, barbiturates, some antibiotics)
• Diabetes, obesity, metabolic syndrome
• Heart disease (independently associated)

When Liver Tests Are Normal But Liver Isn't

Here's something crucial that many don't realize: significant liver disease can exist with normal liver enzymes.

• Early cirrhosis: Enzymes may "burn out" — fewer liver cells left to leak enzymes
• Chronic hepatitis B or C: Can smolder with normal enzymes
• NAFLD: Some patients have normal enzymes despite fibrosis

This is why liver tests alone aren't enough. If there's clinical suspicion — family history of liver disease, metabolic risk factors, unexplained fatigue — further investigation with ultrasound, fibroscan, or specialized markers may be warranted.

The Medications That Affect Your Liver

Your liver processes almost every medication you take. Some are notorious for causing enzyme elevations:

Medication Class	Examples	Pattern
Pain relievers	Paracetamol (high doses), NSAIDs	Hepatocellular damage
Antibiotics	Augmentin, fluoroquinolones, isoniazid	Various patterns
Statins	Atorvastatin, rosuvastatin	Mild elevation (usually harmless)
Anti-epileptics	Phenytoin, valproate	Hepatocellular
Ayurvedic/herbal	Various (often unlabeled)	Unpredictable, sometimes severe

Bilirubin: The Jaundice Marker

Bilirubin is the yellow pigment produced when old red blood cells are broken down. The liver processes it for excretion. When bilirubin rises, you turn yellow — first in the eyes, then the skin.

Types of Bilirubin Elevation

• Unconjugated (indirect) hyperbilirubinemia: The liver hasn't processed it yet. Think hemolysis (excessive red cell breakdown), Gilbert's syndrome
• Conjugated (direct) hyperbilirubinemia: The liver processed it but can't excrete it. Think bile duct obstruction, liver disease

Gilbert's Syndrome — The Benign Yellow

About 5-10% of the population has Gilbert's syndrome — a harmless genetic condition where bilirubin runs mildly high (usually 1.5-3 mg/dL). It's more noticeable when fasting, stressed, or sleep-deprived.

Gilbert's syndrome requires no treatment. The only "risk" is getting worried during routine blood tests. If you've always had mildly elevated bilirubin with normal liver enzymes and feel fine, you probably have Gilbert's.

Albumin and Prothrombin Time: True Function Tests

These actually measure how well the liver is working:

Albumin

Made exclusively by the liver. Low albumin (below 3.5 g/dL) suggests the liver isn't synthesizing properly. Causes include:

• Advanced liver disease/cirrhosis
• Malnutrition
• Kidney disease (nephrotic syndrome — leaking protein)
• Chronic inflammation

Prothrombin Time (PT/INR)

The liver makes clotting factors. Prolonged PT/INR means the liver isn't producing them adequately — a sign of advanced liver dysfunction.

Hepatitis B and C: The Silent Destroyers

Consider Mr. Gupta, 55, who went for a pre-surgery checkup. His liver enzymes were mildly elevated — ALT 58, AST 62. Nothing dramatic. But his hepatitis B surface antigen was positive. Further workup revealed chronic hepatitis B with early cirrhosis.

He'd been living with hepatitis B for probably 30 years without knowing it. By the time his liver showed changes, significant damage had occurred.

Why Hepatitis B Screening Matters

Hepatitis B affects an estimated 40 million Indians. Many don't know they have it. It spreads through:

• Mother to child at birth (most common in India)
• Blood transfusions (before universal screening)
• Unsterile needles, razors, tattoo equipment
• Sexual contact

If you've never been tested, please get tested. If you're negative, get vaccinated. It's one of the few cancers that can be prevented with a vaccine.

Hepatitis C

Less common in India but equally serious. Unlike hepatitis B, hepatitis C is now curable with 8-12 weeks of medication. Screening is recommended if you've ever had a blood transfusion before 1992, or any exposure to potentially contaminated blood.

The Action Plan for Common Scenarios

Reversing Fatty Liver: What Actually Works

The good news: fatty liver in its early stages is completely reversible. The even better news: the same interventions that reverse fatty liver also reduce risk of diabetes, heart disease, and overall mortality.

Weight Loss

Losing 7-10% of body weight can completely reverse fatty liver. For a 75 kg person, that's 5-7 kg. The key is sustained, gradual weight loss — crash diets don't help and may harm.

Exercise

Both aerobic exercise and resistance training help. 150-200 minutes per week of moderate exercise has been shown to reduce liver fat even without weight loss.

Diet Quality

Reduce:

• Refined carbohydrates (maida, white rice, sugar)
• Sugary beverages (the biggest culprit — fructose goes straight to liver fat)
• Processed foods

Increase:

• Protein at every meal
• Vegetables (aim for half your plate)
• Healthy fats (nuts, seeds, olive oil)
• Coffee (yes, coffee is protective for the liver — 2-3 cups daily helps)

Alcohol

Even if fatty liver is non-alcoholic in origin, alcohol makes it worse. Minimizing or eliminating alcohol gives the liver a chance to heal.

Medications

No medication is specifically approved for fatty liver, but several help:

• Vitamin E (for non-diabetics with NASH)
• Pioglitazone (for diabetics with NASH)
• GLP-1 agonists (semaglutide, liraglutide) — showing promise

The Recovery Story

Eight months after diagnosis, Vikram's approach included:

• Ruling out hepatitis B and C (negative)
• Identifying metabolic syndrome (slightly elevated triglycerides, borderline glucose)
• Modifying his diet — more protein, fewer sweets during Diwali, no more "chai-biscuit" three times a day
• Walking 30 minutes daily
• Adding 3 cups of coffee (a happy prescription)

His ALT dropped to 28 U/L. Ultrasound showed mild fatty change — down from Grade 2. His liver was healing.

"I still can't believe I had liver disease. I always thought that was for people who drink."

This is the message everyone should understand: in modern India, fatty liver is a disease of lifestyle, not alcohol. Liver enzymes are telling you something. Listen to them.

What Your Liver Tests Should Look Like

Test	Optimal	Acceptable	Needs Attention
ALT (SGPT)	Below 25 U/L	25-40 U/L	Above 40 U/L
AST (SGOT)	Below 25 U/L	25-35 U/L	Above 35 U/L
GGT	Below 30 U/L	30-50 U/L	Above 50 U/L
Bilirubin	Below 1.0 mg/dL	1.0-1.2 mg/dL	Above 1.2 mg/dL (unless Gilbert's)
Albumin	Above 4.0 g/dL	3.5-4.0 g/dL	Below 3.5 g/dL

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Track your liver function tests with ExaHealth. Upload your lab reports and monitor your ALT, AST, and other markers over time — because catching liver problems early means they're usually reversible.