Blood tests 101: what they show, and when to do them

What blood tests can reveal about your health

If you’ve ever looked at a blood test report and felt overwhelmed by acronyms and numbers, you’re not alone.

Blood tests are one of the most powerful tools in modern medicine. They can:

• Pick up early signs of health problems years before symptoms

• Explain why you feel tired, low in energy or “not quite right”

• Help you track how your lifestyle is affecting your long-term health

At Piko, we use comprehensive blood work not just to “check a box”, but to help you improve energy, performance and longevity. Every test is reviewed by a doctor, and you receive a clear protocol with practical next steps – not just a PDF full of numbers.

In this guide, we’ll walk through:

• The main types of blood tests and what they measure

• When it makes sense to get tested

• How doctors interpret patterns, not just single markers

• How Piko turns data into a personalised plan

The main types of blood tests (and what they measure)

There are hundreds of possible blood tests, but most health check-ups are built from a few core “panels”. Here are the main categories you’ll see on a typical complete blood test / full blood analysis.

1. Full blood count (FBC / CBC) – your blood cells

Often called FBC (full blood count) or CBC (complete blood count), this test looks at the different cells in your blood:

• Red blood cells (RBC, haemoglobin, haematocrit)
  Help carry oxygen around your body. Abnormal levels can be linked to anaemia, dehydration, or other conditions.

• White blood cells (WBC)
  Part of your immune system. Higher or lower levels can suggest infection, inflammation or bone marrow problems.

• Platelets
  Help your blood to clot. Very high or low levels can increase the risk of bleeding or clotting issues.

A CBC is a core part of pretty much every complete blood analysis, and it’s often the first place doctors look if you report fatigue, infections, or unexplained bruising.

2. Metabolic panel – kidneys, electrolytes and blood sugar

A metabolic panel (often called a basic or comprehensive metabolic panel) typically includes:

• Kidney markers – urea, creatinine, and an estimated filtration rate (eGFR)

• Electrolytes – sodium, potassium, sometimes magnesium and calcium

• Glucose – your blood sugar at the time of the test

These markers help doctors understand:

• How well your kidneys are filtering waste

• Whether your electrolytes are in balance (important for heart rhythm, muscles and nerves)

• If your blood sugar is in a healthy range, or if more tests (like HbA1c) are needed

3. Lipid panel – cholesterol and heart risk

A lipid profile checks fats in your blood that are linked to heart disease risk:

• Total cholesterol

• LDL cholesterol (“bad” cholesterol – can build up in arteries)

• HDL cholesterol (“good” cholesterol – helps remove excess cholesterol)

• Triglycerides (a type of fat related to diet and insulin sensitivity)

Doctors don’t just look at one number; they consider ratios and your overall risk factors (age, blood pressure, smoking, family history) to decide whether lifestyle changes or medication might be helpful.

4. Thyroid tests – your internal “metabolic thermostat”

Your thyroid gland controls how fast or slow your body runs. Common thyroid blood tests include:

• TSH (thyroid-stimulating hormone) – the main “first-line” test

• Free T4 and sometimes Free T3 – hormones produced by the thyroid

• Occasionally thyroid antibodies – if an autoimmune thyroid condition is suspected

You might see terms like “bloodwork TSH” or “TFTs” (thyroid function tests) on your report. Abnormal results can be linked with symptoms such as tiredness, weight changes, feeling cold or hot, or mood changes – but diagnosis always depends on the whole clinical picture, not just a number on the page.

5. Vitamin and mineral tests – energy, mood and immunity

Deficiencies in key vitamins and minerals can strongly affect:

• Energy levels

• Mood and brain function

• Immune system and recovery

Common tests in a complete blood test or wellness panel include:

• Vitamin D

• Vitamin B12 and folate

• Iron studies and ferritin (iron stores)

• Sometimes magnesium, calcium and other micronutrients

Rather than testing everything at random, a good panel focuses on nutrients that are commonly low and clinically meaningful.

6. Inflammatory markers – CRP, ESR and more

Blood tests can also look for signs of inflammation, which may suggest infection, an autoimmune condition, or chronic low-grade inflammation:

• CRP (C-reactive protein) – rises with inflammation; high-sensitivity CRP (hs-CRP) can pick up low-grade inflammation associated with heart risk

• ESR (erythrocyte sedimentation rate) – a more general marker of inflammation

On their own, these tests don’t tell you what the cause is, but they give doctors a clue that something may need to be investigated further.

When should you consider a blood test?

There’s no one-size-fits-all answer, but here are some common scenarios where a blood analysis test or full blood analysis is useful.

1. You have new or persistent symptoms

For example:

• Unexplained fatigue or low energy

• Unintentional weight loss or weight gain

• Changes in thirst, urination, or appetite

• Hair loss, brittle nails, or skin changes

• Recurring infections or slow healing

In these cases, blood tests help your doctor rule out or identify likely causes – such as thyroid issues, anaemia, vitamin deficiencies, diabetes, infection or inflammation.

2. You want a proactive health check

Many people feel fine but still want to know “what’s going on under the bonnet”. A complete blood test can:

• Pick up risks like high cholesterol or early glucose changes

• Reveal vitamin or iron deficiencies before they become severe

• Show early signs of liver, kidney or thyroid issues

Think of it as a health MOT: not to create anxiety, but to give you clear information and time to act early.

3. You’re tracking lifestyle or treatment changes

If you’ve:

• Changed your diet (e.g. plant-based, keto, intermittent fasting)

• Started new medication (e.g. statins, thyroid medication)

• Increased training intensity or lost weight

…it can be useful to repeat blood work periodically to see how your body responds.

A good rule of thumb: agree a testing schedule with a healthcare professional rather than repeating tests randomly.

How doctors interpret blood tests (it’s not just about “high” or “low”)

Many people see an “H” or “L” next to a result and immediately panic. But doctors don’t interpret blood tests in isolation. They look at:

1. Your symptoms and medical history

The same result can mean very different things in different people. For example:

• Mildly raised liver enzymes in a heavy drinker vs. someone on new medication

• Slightly low iron in a woman with heavy periods vs. a man with gut symptoms

Your history, medications, and lifestyle all change how a result is interpreted.

2. Patterns across multiple markers

A single “out of range” result often matters less than the overall pattern:

• Low haemoglobin + low ferritin + high TIBC → likely iron deficiency pattern

• High CRP + high WBC + symptoms of infection → likely acute inflammatory process

• High LDL + high triglycerides + high fasting glucose → metabolic risk pattern

Doctors use these patterns to narrow down possibilities and decide what to check next.

3. The reference range isn’t a strict “healthy vs unhealthy” line

Lab reports usually show a reference range based on the middle 95% of results in a population. That means:

• Being slightly outside the range isn’t always dangerous

• Being inside the range doesn’t always guarantee optimal health

For prevention and longevity, clinicians often care about optimal ranges rather than just “not abnormal”.

4. Changes over time

It’s not just where your result sits – it’s also how it moves:

• Is your HbA1c creeping up each year?

• Is your LDL dropping with lifestyle changes?

• Are inflammation markers stable or rising?

Trends help distinguish one-off blips from meaningful changes.

Why you shouldn’t self-diagnose from a lab report

With online access to results, it’s tempting to:

• Google every marker

• Assume “high” means something is seriously wrong

• Start supplements or diets based on numbers alone

This can be risky because:

• Many conditions share similar patterns

• Some “abnormal” results are temporary or caused by infection, dehydration, or lab variation

• Treating numbers without understanding the cause can mask important conditions

Blood tests are powerful, but they are only one part of an overall medical assessment. Always discuss concerns with a qualified professional.

The Piko approach: from blood work to a personalised protocol

At Piko, we designed our health checks to do more than tick boxes.

Here’s how our process works:

1. Comprehensive, goal-focused panels

We don’t just run random tests. Our panels are structured around:

• Energy & fatigue – blood count, iron, B12, vitamin D, thyroid

• Metabolic health & longevity – glucose, HbA1c, lipids, liver, kidney, hs-CRP

• Hormones & overall wellbeing – where appropriate for age and sex

Each complete blood analysis is chosen to give a clear picture of how your body is functioning today – and where you can improve.

2. Doctor review, not auto-generated comments

Every set of blood tests is reviewed by a doctor, who:

• Interprets your results in the context of your age, sex and health history

• Looks for patterns across markers, not isolated numbers

• Identifies where more investigation may be needed

• Highlights areas where lifestyle changes can have the biggest impact

You don’t just get “normal / abnormal” stamped on your results – you get a considered medical view.

3. A clear, practical protocol

Alongside your lab report, you receive a personalised protocol focused on:

• Nutrition suggestions (e.g. more iron-rich foods, fibre for cholesterol, etc.)

• Activity and movement recommendations

• Sleep and stress strategies

• Where appropriate, guidance on when to discuss specific treatments or further tests with your GP or specialist

The aim is simple: turn complex blood work into straightforward actions to improve your energy, performance and long-term health.

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Where to go next

If you’re ready to learn more about specific tests and panels, you might like:

• Our guide to Full Blood Count (FBC/CBC) – what your red and white cells can reveal

• Our deep dive into Metabolic panels & kidney function – urea, creatinine and electrolytes

• Our article on Cholesterol and lipid profiles – understanding your heart risk from a blood test

Blood tests don’t have to be confusing or scary. With the right support, they can become one of the most powerful tools you use to take control of your health today – and protect it for the future.