How to read a blood test report: TSH, HbA1c, liver tests and more

A blood test report can look like a wall of abbreviations and numbers. The useful way to read it is not to focus on one flagged result, but to look at the result, the laboratory's reference range, your symptoms and the reason the test was ordered.

This guide explains some of the markers you are most likely to see on an Indian laboratory report. It is educational, not a diagnosis.

Quick guide to common blood tests

Marker	What it broadly measures
TSH	Thyroid function
HbA1c	Average blood glucose over roughly 2–3 months
Fasting glucose	Blood glucose at the time of the test after fasting
ALT / SGPT	Liver enzyme
AST / SGOT	Liver and muscle enzyme
LDL / HDL	Types of cholesterol
Triglycerides	A type of fat in the blood
Creatinine	A marker used when assessing kidney function
Haemoglobin	Oxygen-carrying protein in red blood cells
WBC	White blood cells, which are part of the immune system
Platelets	Blood cells involved in clotting

Reference ranges differ between laboratories. The range printed on your own report is the one to start with.

TSH: what does it mean?

TSH, or thyroid-stimulating hormone, is produced by the pituitary gland and helps regulate thyroid hormone production.

A TSH result outside the laboratory's range can be a reason for further assessment, but it does not diagnose a thyroid condition by itself. Doctors may consider free T4, symptoms, medicines and previous results before deciding what it means.

Fasting needed? Usually no, unless your doctor has ordered other tests that require fasting.

HbA1c: your longer-term blood sugar picture

HbA1c reflects average blood glucose over the preceding several weeks, commonly described as roughly two to three months. It is different from a fasting glucose test, which measures blood glucose at one point in time.

Common diagnostic thresholds used in clinical practice include:

• Below 5.7%: generally in the normal range
• 5.7% to 6.4%: commonly classified as prediabetes range
• 6.5% or above: diabetes range, usually requiring appropriate clinical confirmation

Your doctor may interpret the result differently depending on your circumstances, medicines and other health factors.

Fasting needed? No.

If you need a repeat HbA1c or other routine blood work, you can compare diagnostic centres in Bangalore or search by your city or pincode on Locatemycentre.

ALT and AST: common liver-related markers

ALT, also called SGPT, and AST, also called SGOT, are enzymes measured in blood. Higher levels can occur when cells are injured, although these tests do not identify the cause on their own.

AST can also come from muscle, so an elevated AST does not automatically mean a liver problem. Doctors usually look at ALT, AST, bilirubin, other liver tests, symptoms, medicines and medical history together.

Fasting needed? Not usually for these tests alone. Follow the preparation instructions for the full panel you have been prescribed.

Cholesterol and triglycerides

A lipid profile commonly includes total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides.

LDL is often described as the cholesterol associated with plaque formation in arteries. HDL is another type of cholesterol that is considered in cardiovascular risk assessment. Triglycerides are a type of blood fat.

There is no single cholesterol number that tells the whole story. Your doctor may consider age, blood pressure, diabetes, smoking, family history and other risk factors when interpreting a lipid profile.

Fasting needed? It depends on the test and clinical situation. Follow the instructions from your doctor or laboratory.

For current price guidance, see blood test prices in Bangalore.

Vitamin D and vitamin B12

Vitamin D is important for bone health and calcium metabolism. Vitamin B12 is involved in red blood cell formation and normal nerve function.

Low results can have several causes, and the number alone does not explain why a deficiency occurred. Your doctor may consider diet, medicines, symptoms and other tests before recommending treatment.

Fasting needed? Usually no.

Creatinine and kidney function

Creatinine is a waste product that is commonly measured when assessing kidney function. Your report may also include an estimated glomerular filtration rate, or eGFR, which provides additional information about kidney filtration.

One creatinine result is not enough to diagnose chronic kidney disease. Doctors consider previous results, age, body size, medicines and other clinical information.

Fasting needed? Usually no for creatinine alone, although preparation can vary when it is part of a larger panel.

CBC: the basics

A complete blood count, or CBC, measures several components of blood.

Haemoglobin helps carry oxygen. A low result can be seen with anaemia, although the cause needs further evaluation.

White blood cells are part of the immune system. High or low counts can occur for many reasons, including infections, medicines and other conditions.

Platelets help blood clot. A result outside the reference range needs to be interpreted in context rather than treated as a diagnosis by itself.

What if one number is flagged high or low?

Don't panic.

Laboratories flag results outside their reference ranges, but a small variation does not automatically mean that something is wrong. Reference ranges are statistical tools, and they differ between laboratories.

Pay closer attention when:

• The result is substantially outside the stated range.
• The result has changed significantly from your previous tests.
• You have symptoms that need medical attention.
• Your doctor ordered the test to investigate a specific condition.
• Several related markers are abnormal together.

If you have a concerning result, discuss it with the clinician who ordered the test rather than trying to interpret it in isolation.

How to get a useful follow-up test

If you are repeating a test, using the same laboratory can make trends easier to compare because reference ranges and testing methods may differ.

Follow the laboratory's fasting and preparation instructions, tell the staff about relevant medicines and keep previous reports available for comparison.

If you are looking for a new lab, find diagnostic centres near you or browse by city and test.

Related Locatemycentre guides

• How to choose a diagnostic centre in Bangalore
• Blood test prices in Bangalore
• Home sample collection in Delhi

This article is for general education and does not replace medical advice. Reference ranges and clinical interpretation vary. Speak with a qualified healthcare professional about your own results.