What do blood tests check for?

Blood tests are one of the most common and useful tools in healthcare. They can potentially reveal what’s happening inside your body, often before any symptoms appear. From monitoring your organ function to checking nutrient levels, blood tests provide essential insights that can support early detection, prevention and ongoing health management.

This article explains what blood tests check for, why they’re important, the main types of blood tests available and how they can help you take a proactive approach to your health.

Why are blood tests important?

Many health conditions develop gradually and may not cause obvious symptoms at first. Without testing, it’s possible to live with an undetected issue for months or even years. Blood tests help identify early warning signs and track subtle changes in your body, giving you the opportunity to take action before a condition progresses.

For example, raised cholesterol, early diabetes, thyroid imbalances or vitamin deficiencies can all be detected through simple blood checks. These insights allow you and your healthcare provider to make informed decisions about lifestyle changes, monitoring or treatment.

Regular blood tests can also give reassurance when results come back within the expected range, offering peace of mind and helping you stay in control of your health.

What do blood tests look for?

Blood tests measure a wide range of markers that reflect how well your body is working. Depending on the type of test, they can check your organ function, identify risk factors for chronic disease or highlight deficiencies that may be affecting your energy and wellbeing.

Here are some of the most common things blood tests check for:

1. Full blood count (FBC)

A full blood count looks at the different cells in your blood, including:

• Red blood cells (carry oxygen)

• White blood cells (fight infection)

• Platelets (help blood clotting)

It can detect signs of infection, anaemia, immune system changes or certain blood-related conditions.

2. Cholesterol and lipid profile

This measures different types of fats in your blood, including:

• LDL (“bad”) cholesterol

• HDL (“good”) cholesterol

• Triglycerides

High cholesterol or an imbalance in these markers can increase the risk of heart disease and stroke.

3. Blood glucose

Glucose testing checks how much sugar is in your blood. Elevated results may indicate prediabetes or diabetes, both of which benefit from early management.

4. Liver function tests

These assess enzymes and proteins linked to liver health. Abnormal results could point to liver damage, fatty liver disease or other underlying issues, sometimes before symptoms like fatigue or jaundice appear.

5. Kidney function tests

Kidneys filter waste from your blood. Tests such as creatinine and eGFR (estimated glomerular filtration rate) show how effectively they are working, helping to spot early signs of kidney disease.

6. Thyroid function tests

Your thyroid regulates metabolism, energy and mood. Tests check hormone levels (TSH, T3 and T4) to detect overactive or underactive thyroid function.

7. Inflammatory markers

Tests such as CRP (C-reactive protein) can pick up signs of inflammation in the body. While inflammation can result from infection, raised levels may also be linked to long-term chronic conditions like heart disease, or autoimmune conditions.

8. Vitamin and mineral levels

Nutrient testing is often overlooked, but deficiencies are surprisingly common. Blood tests can measure:

• Vitamin D – important for bone strength, immune function and mood regulation.

• Vitamin B12 – essential for nerve function, red blood cell production and energy.

• Folate (Vitamin B9) – needed for cell repair and growth.

• Iron – low levels can lead to anaemia, fatigue and reduced concentration.

Detecting deficiencies can explain vague symptoms such as tiredness, low mood, muscle aches or “brain fog.” Testing is particularly valuable for people following vegetarian, vegan or restrictive diets.

9. Hormone levels

Hormones control everything from energy and metabolism to fertility and stress response. Blood tests can assess:

• Sex hormones such as oestrogen, progesterone and testosterone, which influence reproductive health, bone strength and mood.

• Cortisol, the “stress hormone,” which can impact energy balance and weight.

• Insulin, linked to blood sugar regulation and diabetes risk.

Tracking hormone levels can highlight imbalances that affect daily life and long-term health.

The benefits of blood testing

The value of blood tests goes beyond just spotting problems. They also help you track progress, measure the impact of lifestyle changes and guide preventive healthcare decisions.

Some key benefits include:

• Early detection of risk factors – Identifying high cholesterol, raised blood sugar or nutrient deficiencies before they become more serious.

• Avoiding complications – Managing conditions like anaemia or thyroid disorders earlier can help prevent long-term complications.

• Monitoring treatment and lifestyle changes – Regular blood tests show how your body is responding to a new diet, exercise plan or medication.

• Personalised health insights – Understanding your unique blood markers allows for tailored advice and support.

• Peace of mind – Knowing that your key health markers are within a healthy range can provide reassurance.

Can a blood test detect cancer?

Blood tests alone cannot usually confirm cancer, but they may pick up markers that suggest further investigation is needed. Some tests look for “tumour markers”, substances produced by certain cancers, while others may show unexplained abnormalities (such as changes in blood cell counts) that warrant follow-up.

If a blood test raises concerns, your GP or healthcare provider would recommend additional checks such as scans or specialist referrals.

Who should consider regular blood testing?

Blood tests can benefit almost anyone, but they may be especially useful if you:

• Are over the age of 40

• Have a family history of heart disease, diabetes or thyroid disorders

• Live with high blood pressure, obesity or high cholesterol

• Experience unexplained symptoms such as tiredness, low mood or “brain fog”

• Follow a restrictive diet and want to check your nutrient levels

• Manage a long-term condition and want to monitor progress

• Simply want to take a proactive approach to your wellbeing

Even if you feel well, blood testing can highlight hidden risks and give you the confidence that nothing is developing beneath the surface.

What happens if your results are outside the normal range?

Abnormal blood test results don’t always mean something is wrong. Factors such as stress, diet, dehydration or recent illness can affect results temporarily.

If results fall outside the expected range, your healthcare provider will look at the bigger picture, including your medical history, lifestyle and any symptoms, before suggesting next steps. These might include:

• Repeating the test after a short time

• Additional investigations

• Simple lifestyle adjustments

• Medication or ongoing monitoring

It’s important to remember that blood tests are just one piece of the puzzle. They provide valuable insights but are most useful when considered alongside your overall health and circumstances.

Make proactive choices with blood testing

Blood tests can play a key role in helping you understand your health. By highlighting risk factors, detecting changes early and supporting personalised care, they allow you to take control before problems develop.

If you’d like to take a more proactive approach, a private health assessment could be a great place to start. At Bluecrest Wellness, our comprehensive Health MOTs include a wide range of blood tests alongside other key checks. You’ll receive clear, easy-to-understand results, plus access to a 24/7 GP helpline for a full 12 months.

With convenient clinics across the UK and fast results from trusted UK laboratories, you can feel confident that you’re getting accurate, reliable insights into your health.

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