What shows up in a blood test?
Wondering what a blood test can actually detect? Our complete guide has everything you need to know about you can find out from a home blood test.
Your blood is an incredible window into your inner health. It transports hormones, delivers nutrients, and transports waste all around your body. And almost all of these molecules can be isolated and measured in a blood test, giving you a snapshot of your health at that point in time
You may have a blood test as part of a regular check-up to help investigate symptoms, diagnose a condition, or keep track of your risk of long-term chronic conditions, like heart disease and diabetes.
From getting to the bottom of unwanted symptoms to detecting a condition before it gets out of control, blood tests can give you invaluable insights into your health.
In this article we'll explain:
- Biomarkers: What can a blood test detect?
- Different types of blood tests
- What health conditions show up in a blood test?
- What can’t a blood test detect?
- Do I have to be ill to have a blood test?
- How often should I have a blood test?
Biomarkers: What can a blood test detect?
A blood test examines the different substances circulating in your blood. These molecules, also known as biomarkers, can indicate whether normal or abnormal processes are happening in your body.
Some common biomarkers blood tests measure include:
- Blood cells (three types: red, white, and platelets)
- Biomolecules (such as glucose, cholesterol, and enzymes)
- Proteins and hormones
- Waste products (kidney and liver markers)
- Immune markers (antibodies or inflammation)
Blood cells
Your blood contains three types of cells, each with a specific role.
They are:
- Red blood cells – carry oxygen from the lungs to the body
- White blood cells – part of your immune system
- Platelets – help the blood clot after injury
Measuring these can give insights into oxygen transport, nutrient levels, immune activity, and clotting function.
Biomolecules
Biomolecules are small chemical substances found in your body that are essential for it to function properly
These include:
- Glucose – indicates how the body regulates blood sugar
- Lipids – such as cholesterol and triglycerides, good indicators for cardiovascular health and risk of heart disease
- Enzymes – molecules that help bodily processes happen
- Proteins – support fluid balance, blood clotting, and immune defence
Measuring biomolecules can reflect how your body processes, or metabolises, energy and fats.
Hormones
Growth, reproductive organs, mood, and metabolism are all governed by chemical messengers known as hormones. Humans have over 50 hormones in varying levels and measuring them can help assess the health of glands such as thyroid or adrenal, as well as reproductive health.
Waste products
As your body processes energy, it also produces waste.
Waste products are filtered by:
- Kidneys – filter waste from blood
- Liver – process toxins and metabolic by products
A blood test can determine the levels of waste in your blood which can indicate the health of your organ function.
Immune and inflammation markers
You can use blood tests to monitor your immune system activity.
This includes:
- Antibodies – part of your body’s response to infection or autoimmune conditions
- Inflammation markers – also rise in response to injury, infection, or chronic disease
These markers can help explain if your symptoms are related to immune activation.
Different types of blood tests
Now we know what molecules blood tests can identify, lets take a look at some common terms and types of blood tests you may come across, and what they are used for.
Routine blood test
A routine blood test is one that your doctor is most likely to order to investigate a wide range of symptoms and conditions.
They are often used to:
- Screen for common conditions such as anaemia, diabetes, or high cholesterol
- Monitor long-term health trends
- Detect early changes before symptoms appear
The two main components of a blood test are a haematology profile and a biochemistry profile.
Other types of blood tests include those that measure your hormones, known as endocrinology profiles, and ones that focus on immune markers, or immunology profiles.
What is a haematology profile?
Haematology profiles are also known as a full blood count (FBC) or complete blood count (CBC). They assess your blood and identify abnormalities that may indicate a problem.
Different components of blood cells, such as your red and white blood cells, are examined, and they can detect or monitor conditions like anaemia, infection, inflammation, or leukaemia.
What is a biochemistry profile?
Biochemistry profiles measure substances in the blood or urine, including hormones, proteins, salt levels, and liver enzymes. Biochemistry tests evaluate the functional capacity of several critical organs.
They are used to assess:
- Blood sugar and cholesterol levels (also known as a lipid profile)
- Liver and kidney function
- Electrolyte and fluid balance
These tests are widely used for both screening and ongoing monitoring.
What is an endocrinology profile?
An endocrinology profile is a targeted set of blood tests used to evaluate the function of your hormone-producing glands. It helps diagnose imbalances causing certain conditions such as thyroid or adrenal, among others.
What is an immunology profile?
Immunology tests look for and measure antibodies produced by your immune system to overcome a certain infection. They can also screen for autoimmune disease, such as coeliac, when the body produces antibodies against its tissues.
What health conditions show up in a blood test?
Although blood tests can’t diagnose most conditions on their own, they are often the most reliable way of getting insights that support a diagnosis or identifying a potential health risk.
Some of the more common conditions you may look for with a blood test include:
- Metabolic conditions such as diabetes
- Cardiovascular risk including cholesterol abnormalities
- Iron deficiency anaemia and blood disorders
- Autoimmune and inflammatory conditions
- Liver and kidney conditions
- Hormonal imbalances such as thyroid, polycystic ovary syndrome, or low testosterone
- Nutritional deficiencies such as mineral, vitamin, and omega levels
What can’t a blood test detect?
It’s important to understand the limitations of blood tests. Not all conditions cause measurable changes in the blood, especially in early stages.
Blood tests usually can’t detect:
- Most cancers
- Structural damage
- Mental health conditions
- Neurological conditions
Additionally, results from a blood test aren’t a diagnosis but rather a tool to aid a diagnosis.
Clinicians will interpret your results alongside other information – symptoms, medical history, physical examination, and use this to give you a diagnosis.
Do I have to be ill to have a blood test?
Although blood tests are an invaluable tool to help diagnose a condition or investigate symptoms, you don’t have to be ill to benefit from a blood test. Blood tests are an excellent screening tool for picking up health risks.
Other reasons why people have blood tests:
- Investigate a family history of a particular condition (such as heart disease)
- Understand health risks
- Optimise nutrition
- Optimise sports performance
- Understand fertility
- For occupational reasons (immunity tests and exposure to work-related toxins)
Next steps
Some tests should be done as soon as possible, if you think you have an infection or condition, or if you're experiencing symptoms, for example. Once they’re done, and the infection or condition has been ruled out, there’s no reason for you to repeat that test .
For most healthy people, checks are advisable to keep on top of your healthcare. You can do this by monitoring your diet and lifestyle, key measurements like your weight and waist circumference and by checking your blood biomarkers.
Need help choosing a blood test? Or wondering how often to test? Head over to our blogs, for more information.
References
- Strimbu, K. and Tavel, J., 2010. What are biomarkers?. Current Opinion in HIV and AIDS, 5(6), pp.463-466.
- NHS UK. 2023. Blood tests, NHS online [Accessed 18 May 2026].
- Nicholson, L., 2016. The immune system. Essays in Biochemistry, 60(3), pp.275-301.
- Kidney Research UK. 2026 Kidney research. [online] [Accessed: 18 May 2026]
- Medical news today.com. 2022. Uric acid levels: High and low, symptoms, and relation to gout. [online] [Accessed 18 May 2026].
- Centers for Disease Control and Prevention. 2022. LDL and HDL Cholesterol: “Bad” and “Good” Cholesterol. [online] [Accessed 18 May 2026].
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