Understanding the Different Types of Blood Tests and their Significance

In short: Common blood tests include the full blood count (FBC), cholesterol (lipid) profile, liver and kidney function tests, thyroid tests, iron studies, clotting tests and HbA1c for diabetes. Each checks a different part of your health, and together they can pick up problems early. Results should always be interpreted by a doctor alongside your symptoms and history.

Introduction

Blood tests are essential diagnostic tools that provide valuable insight into your health. They help detect medical conditions, monitor how your organs are working and assess your overall wellbeing. Understanding the different types of blood tests, and what they show, is a big step towards proactive health management. Here we explore the most common blood tests and their significance.

Full Blood Count (FBC)

The Full Blood Count (FBC), also known as a Complete Blood Count (CBC), is one of the most frequently performed blood tests. It gives a broad overview of your blood and measures three main components:

1. Red blood cells (RBC): Carry oxygen around the body. The FBC helps diagnose conditions such as anaemia and polycythaemia.
2. White blood cells (WBC): Part of the immune system that defends against infection. Abnormal counts can point to infection, inflammation or, rarely, leukaemia.
3. Platelets: Help blood clot. The FBC can reveal bleeding disorders and some bone marrow conditions.

Lipid Profile

A lipid profile measures fats in your blood, including cholesterol and triglycerides. Raised levels are a risk factor for heart and circulatory disease. It typically includes:

1. Total cholesterol: The total amount of cholesterol in your blood, including "good" (HDL) and "bad" (LDL) cholesterol.
2. HDL cholesterol: High-density lipoprotein, or "good" cholesterol, helps remove excess cholesterol from the arteries.
3. LDL cholesterol: Low-density lipoprotein, or "bad" cholesterol, can build up in the arteries and increase the risk of heart disease.
4. Triglycerides: High levels can also contribute to heart disease and are often linked to obesity and poorly controlled diabetes.

Liver Function Tests (LFTs)

Liver function tests assess the health of the liver, which plays a vital role in detoxification, nutrient processing and bile production. They include:

1. Alanine aminotransferase (ALT): Raised ALT may indicate liver damage or disease, such as hepatitis or fatty liver.
2. Aspartate aminotransferase (AST): AST can rise due to liver or muscle damage.
3. Alkaline phosphatase (ALP): Raised ALP may point to liver or bone problems, and is often used to help diagnose conditions such as gallbladder disease.
4. Bilirubin: High bilirubin may suggest liver disease or bile duct problems, potentially causing jaundice.

Kidney Function Tests

Kidney function tests assess how well your kidneys filter waste from the blood. Key tests include:

1. Creatinine: Raised creatinine suggests reduced kidney function, which can be seen in kidney disease or dehydration.
2. Urea (blood urea nitrogen): Measures urea in the blood. High levels may indicate kidney disease or dehydration.
3. Estimated glomerular filtration rate (eGFR): Estimates how efficiently the kidneys filter waste. A low eGFR may indicate kidney damage or disease.

Thyroid Function Tests

Thyroid function tests check the thyroid gland, which regulates metabolism and energy levels. They include:

1. Thyroid stimulating hormone (TSH): Helps diagnose thyroid disorders. A raised TSH suggests an underactive thyroid (hypothyroidism), while a low TSH may indicate an overactive thyroid (hyperthyroidism).
2. Free T4 and free T3: These thyroid hormones show how the gland is functioning. Abnormal levels can indicate thyroid dysfunction.

Iron Studies

Iron studies evaluate iron levels in the blood, which are crucial for producing red blood cells. Key measurements include:

1. Serum iron: The amount of iron circulating in the blood. Low levels may suggest iron-deficiency anaemia.
2. Ferritin: A protein that stores iron in the body. Low ferritin indicates low iron stores, even before serum iron falls.
3. Transferrin saturation: Shows how much of the iron-carrying protein transferrin is loaded with iron. Abnormal values may indicate iron metabolism disorders.

Coagulation Tests

Coagulation tests assess how well your blood clots. They include:

1. Prothrombin time (PT): Measures how long blood takes to clot. It is often used to monitor blood-thinning medication (anticoagulants) such as warfarin.
2. Activated partial thromboplastin time (APTT): Assesses clotting ability and is used to monitor some anticoagulants, such as heparin.
3. International normalised ratio (INR): Calculated from the PT to standardise clotting results between laboratories.

Diabetes Blood Tests

Diabetes blood tests help diagnose and manage diabetes. Common tests include:

1. Fasting blood glucose: Measures blood glucose after an overnight fast. Raised levels may indicate diabetes.
2. HbA1c (haemoglobin A1c): Reflects your average blood sugar over the past two to three months and is essential for long-term diabetes management.

Learn more on the NHS blood tests page and about the free NHS Health Check.

Conclusion

Understanding the different blood tests is essential for monitoring your health and catching problems early. Regular check-ups with appropriate blood tests help healthcare professionals diagnose issues and plan effective treatment. Speak to a healthcare professional about which tests suit your age, health and risk factors, so you can take a proactive approach to your wellbeing.

Frequently asked questions

Do I need to fast before a blood test?

Most blood tests don't need fasting. Some, such as fasting glucose, may do; you will be told if you need to fast.

What does a full blood count show?

An FBC measures red cells, white cells and platelets, and can point to conditions such as anaemia, infection or bleeding problems.

How often should I have a blood test?

There's no single answer; it depends on your age, health and risk factors. In England, adults aged 40 to 74 are offered a free NHS Health Check every 5 years.

What if my result is outside the normal range?

A result slightly outside the range isn't always a problem. Discuss it with your doctor, who will interpret it in context.

Book a test at E&J Bio

Walk-ins are welcome at our clinic at 305 Neasden Lane, London NW10 1QR. We are open 7 days a week, including Sundays, or you can book online at ejbio.co.uk/shop.

• Full Blood Count (FBC) (results: same day)
• Cholesterol Panel (Serum Lipids) (results: same day)
• Liver Function Test (LFT) (results: same day)
• Kidney Function Panel 1 (results: same day)
• Thyroid Panel 1 (results: same day)
• Iron Status Profile (results: next day)
• HbA1c (results: same day)
• Full Body MOT Health Check (results: next day)

This article is for general information only. Please discuss your results, and any symptoms, with a doctor or other qualified healthcare professional.