How to read an LFT blood test report is a question doctors get from patients almost every day — and understandably so. A Liver Function Test report arrives with nine or ten numbers, unfamiliar abbreviations like SGOT, SGPT, and ALP, and very little explanation of what any of it actually means for your health.

This guide walks you through every single parameter on a standard LFT report — Total Bilirubin, Direct Bilirubin, Indirect Bilirubin, SGOT, SGPT, Alkaline Phosphatase, Total Protein, Albumin, Globulin, and A/G Ratio — with plain-language explanations, real reference ranges, and clinical context that makes the numbers meaningful.

Whether you are a patient trying to understand your own report or a junior doctor building clinical confidence, by the end of this article you will know exactly what each value measures, what it means when it is high or low, and how to put it all together into a clinical picture.

What Is an LFT Blood Test?

LFT stands for Liver Function Test — a panel of blood tests that assess how well your liver is working. It is ordered from a serum sample (the clear liquid part of your blood after it clots) and is one of the most commonly requested investigations in both outpatient and inpatient medicine.

A normal LFT does not mean your liver is completely healthy — some conditions can be present with a normal LFT. But an abnormal LFT is always a signal worth investigating. The pattern of abnormality — which values are raised and by how much — is what guides the diagnosis.

Bilirubin — The Jaundice Marker

Bilirubin is the yellow pigment produced when old red blood cells are broken down. The liver processes bilirubin and excretes it into bile. When this process goes wrong — whether because of excess red cell breakdown, liver cell damage, or a blocked bile duct — bilirubin accumulates in the blood and causes jaundice (yellow skin and eyes).

A standard LFT reports bilirubin in three ways: Total, Direct, and Indirect. Understanding the difference between them is the key to diagnosing the type of jaundice.

Total Bilirubin (Normal: 0.3 – 1.2 mg/dL)

Total bilirubin is the sum of Direct and Indirect bilirubin. It is the headline number. Anything above 1.2 mg/dL is elevated. Clinically visible jaundice usually appears when Total Bilirubin exceeds 2.5 – 3.0 mg/dL — before that point, mild elevation may go unnoticed without a blood test.

Direct Bilirubin / Conjugated Bilirubin (Normal: ≤ 0.2 mg/dL)

Direct bilirubin is bilirubin that has already been processed (conjugated) by the liver and is ready for excretion into bile. When it is elevated, it means the liver has done its job but the bile cannot flow out — either because the bile duct is blocked (gallstone, tumour) or because there is liver cell damage.

Indirect Bilirubin / Unconjugated Bilirubin (Normal: 0.1 – 1.0 mg/dL)

Indirect bilirubin is the raw, unprocessed form — it has been released from broken-down red cells but not yet processed by the liver. High indirect bilirubin means either too many red cells are breaking down (haemolysis) or the liver cannot keep up with processing (as in Gilbert’s syndrome or neonatal jaundice).

SGOT and SGPT — The Liver Enzyme Pair

SGOT and SGPT are the two most important liver enzymes on the LFT panel. They are released into the bloodstream when liver cells are damaged or dying. The higher these values, the more active the liver cell injury.

SGOT (AST) — Serum Glutamic Oxaloacetic Transaminase (Normal: up to 40 U/L)

SGOT, also called AST (Aspartate Aminotransferase), is found not only in the liver but also in heart muscle, skeletal muscle, kidneys, and red blood cells. Because it is less liver-specific than SGPT, an isolated SGOT rise should prompt you to consider non-liver causes — especially heart attack (SGOT rises within hours of a myocardial infarction) or muscle damage (rhabdomyolysis).

SGPT (ALT) — Serum Glutamic Pyruvic Transaminase (Normal: up to 40 U/L)

SGPT, also called ALT (Alanine Aminotransferase), is the more liver-specific of the two. It is predominantly found in liver cells, so a raised SGPT almost always points to hepatocellular (liver cell) injury. It is the more sensitive and specific marker for active liver damage.

Alkaline Phosphatase (ALP) — The Cholestasis Marker

Alkaline Phosphatase (also written as ALPI on some lab reports) is an enzyme found in the bile ducts, bone, intestine, and placenta. Normal range: 30 – 120 U/L. On a liver report, a raised ALP primarily signals cholestasis — a problem with bile flow rather than liver cell damage.

Total Protein, Albumin, and Globulin — The Liver’s Manufacturing Report

The liver is the body’s main protein factory. These three values tell you how well it is doing that job — and they are among the most important markers of chronic liver function. While SGOT and SGPT reflect acute injury, low albumin and low total protein reflect long-standing liver damage.

Total Protein (Normal: 6.6 – 8.8 g/dL)

Total protein is the combined measurement of albumin and globulin in your blood. A low total protein (<6.6 g/dL) suggests either the liver is not making enough protein (chronic liver disease, malnutrition) or protein is being lost from the body (nephrotic syndrome, protein-losing enteropathy).

Albumin (Normal: 3.5 – 5.0 g/dL)

Albumin is the most abundant protein in the blood, made exclusively by the liver. It performs two critical functions: maintaining blood oncotic pressure (keeping fluid inside blood vessels) and transporting hormones, drugs, and fatty acids around the body.

Low albumin (hypoalbuminaemia) is one of the most reliable markers of chronic liver dysfunction. When albumin falls below 3.5 g/dL, fluid starts leaking out of blood vessels into the body cavities — causing oedema (swollen ankles), ascites (fluid in the abdomen), and pleural effusions. A persistently low albumin in a liver patient is a serious sign.

Serum Globulin (Calculated: Total Protein − Albumin)

Globulins are a group of proteins that include immunoglobulins (antibodies) and many transport proteins. Globulin is not directly measured — it is calculated by subtracting albumin from total protein. Normal range is approximately 2.0 – 3.5 g/dL.

A raised globulin (hyperglobulinaemia) is seen in chronic infections (TB, HIV, malaria), autoimmune liver disease, and multiple myeloma. A low globulin is unusual but can indicate immunodeficiency.

A/G Ratio — The Albumin-to-Globulin Ratio

The A/G (Albumin-to-Globulin) Ratio is calculated by dividing albumin by globulin. Normal range: 1.2 – 2.0. In healthy people, albumin is higher than globulin, so the ratio is greater than 1.

How to Read an LFT Report Step by Step

Here is the systematic approach clinicians use when reviewing a liver function test panel:

1. Look at Total Bilirubin first — is jaundice biochemically present? (>1.2 mg/dL)
2. Is it Direct or Indirect dominant? — this tells you pre-hepatic, hepatic, or post-hepatic
3. Check SGPT (ALT) — elevated = active liver cell damage
4. Compare SGOT and SGPT — is SGOT:SGPT > 2? Think alcohol. Is SGPT > SGOT? Think viral hepatitis
5. Check ALP — disproportionately high ALP with high Direct Bilirubin = bile duct obstruction
6. Look at Albumin — is liver synthetic function preserved? Low albumin = chronic/severe disease
7. Check A/G Ratio — reversed ratio (<1) suggests cirrhosis or chronic inflammatory state
8. Put it all together — is this acute injury, chronic disease, obstruction, or haemolysis?

Common Mistakes When Reading an LFT Report

• Treating any raised bilirubin as hepatitis — always split Direct vs Indirect first; high Indirect may just be Gilbert’s syndrome (benign)
• Ignoring a raised ALP in isolation — always consider bone disease before assuming liver pathology
• Missing the SGOT:SGPT ratio — one of the most useful diagnostic clues for alcoholic liver disease, often overlooked
• Declaring the liver normal because enzymes are normal — advanced cirrhosis can have near-normal SGOT/SGPT; always check albumin and A/G ratio
• Not considering pregnancy for a raised ALP — placental ALP is normal in the third trimester
• Interpreting albumin without nutritional context — severe malnutrition and nephrotic syndrome also lower albumin independently of liver function

A Note for Patients

If you have received an LFT report and some values are outside the normal range, do not panic. A single mildly abnormal reading — especially a slightly raised SGPT or a bilirubin at 1.4 mg/dL — does not diagnose liver disease. Many things affect these values temporarily: a viral illness the week before, a new medication, a heavy meal, even vigorous exercise (which can raise SGOT).

What your doctor is looking for is a pattern — which values are raised, by how much, and whether they are improving or worsening over time. A single LFT is a starting point, not a verdict.

If your SGPT is more than three times the upper limit of normal, or if your bilirubin is high enough to cause visible yellow eyes or skin, that warrants prompt medical attention. Do not delay in those situations.

Summary

• LFT measures liver damage (enzymes), metabolism (bilirubin), and synthetic function (proteins)
• Total Bilirubin — overall jaundice marker; normal up to 1.2 mg/dL
• Direct vs Indirect Bilirubin — the pattern identifies the type of jaundice (pre-hepatic / hepatic / post-hepatic)
• SGPT (ALT) — most liver-specific enzyme; elevated = active hepatocellular injury
• SGOT (AST) — less specific; SGOT:SGPT > 2 strongly suggests alcoholic liver disease
• ALP — marker of bile duct/cholestatic disease; also raised in bone disease and pregnancy
• Total Protein — reflects overall protein status; low in chronic liver disease and malnutrition
• Albumin — best marker of chronic liver synthetic function; low albumin = serious concern
• A/G Ratio — reversed ratio (<1.0) suggests cirrhosis or chronic inflammatory state
• Always interpret LFT as a panel, not individual values — the pattern is the diagnosis

References

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2. National Institute for Health and Care Excellence (NICE). Liver function tests — abnormal results. London: NICE; 2023.
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4. European Association for the Study of the Liver (EASL). EASL Clinical Practice Guidelines: Management of chronic hepatitis B virus infection. J Hepatol. 2017;67(2):370–398.
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6. Indian Council of Medical Research (ICMR). Standard Treatment Guidelines — Cirrhosis of Liver. New Delhi: ICMR; 2021.