Blood tests are one of the most helpful tools your GP (General Practitioner) uses to check your health. Whether you’re feeling unwell, managing a long-term condition, or simply having a routine health check, UK blood tests are a key part of understanding what’s going on inside your body.

What is a blood test?
A blood test involves taking a small sample of your blood, usually from a vein in your arm, which is then sent to a lab for analysis. Depending on the test, it can help diagnose diseases, check organ function, monitor medication, or identify vitamin and mineral deficiencies.

Common NHS blood tests and what they mean:

1. Complete Blood Count (CBC)
Purpose: A CBC test checks your red cells, white cells, and platelets to detect issues like anaemia, infections, or blood disorders.

What it measures:

• Red blood cells (RBCs): RBCs carry oxygen in the blood
• White blood cells (WBC): Fight infection in our body
• Platelets: Help with blood clotting
• Haemoglobin (Hb): This is the oxygen-carrying protein in red blood cells

Why it's done:

• RBCs- It helps detect anaemia by measuring red blood cell levels, which can indicate if your body is getting enough oxygen.

Severity	Men (Hb g/L)	Women (Hb g/L)	Pregnant women (Hb g/L)
Mild anaemia	110–129	110–119	100–109
Moderate Anaemia	80–109	80–109	70–99
Severe anaemia	<80	<80	<70

• WBCs - It identifies infections or inflammation by checking white blood cell counts, as these often rise or fall in response to illness. Normal levels of WBC are 4000 to 11000 (cells/μL).
• Platelets- They can reveal bleeding or clotting problems by analysing platelet levels, which are essential for normal blood clotting.
• They may also help detect blood cancers such as leukaemia, by identifying abnormal changes in blood cell production.

2. Kidney Function Test (KFT)
Purpose: Assesses how well your kidneys are working and whether your fluid and salt balance is normal.

What Does a KFT Measure?

1. Urea – A waste product formed from the breakdown of proteins. High levels may indicate reduced kidney function or dehydration.
2. Creatinine – A waste product from muscle metabolism. It’s a key marker for kidney performance; elevated levels often suggest kidney dysfunction.
3. GFR (Glomerular Filtration Rate) – A calculation based on creatinine that estimates how efficiently your kidneys are filtering blood.
4. Electrolytes – Especially sodium, potassium, and chloride. Imbalances can indicate kidney or metabolic issues.

Why is it done?

• To detect early signs of kidney disease
• To monitor existing kidney conditions
• To check for side effects of medications that can impact the kidneys
• To evaluate symptoms like swelling, fatigue, or changes in urination

3. Liver Function Test (LFT)
Purpose: Assesses liver health and detects liver damage or disease.

What it measures:

1. ALT (Alanine Aminotransferase): An enzyme found in the liver. High levels usually suggest liver inflammation or damage.
2. AST (Aspartate Aminotransferase): Another enzyme linked to liver health. It may rise with liver damage, but is also found in other organs.
3. ALP (Alkaline Phosphatase): Elevated levels may indicate issues with the bile ducts, liver, or bones.
4. GGT (Gamma-Glutamyl Transferase): Often rises with alcohol use or bile duct problems.
5. Bilirubin: A waste product from the breakdown of red blood cells. High levels can cause jaundice and may indicate liver or bile duct issues.
6. Albumin and Total Protein: Proteins made by the liver. Low levels can point to chronic liver disease or nutritional problems.

Why it's done:

• To check for liver diseases like hepatitis or fatty liver
• To monitor liver damage from alcohol, infections, or medications
• To investigate symptoms like jaundice, fatigue, or abdominal pain
• Monitor the effect of medications on the liver

4. Thyroid Function Test (TFT)
Purpose: Checks if your thyroid gland is underactive or overactive.

What Do TFTs Measure?

1. TSH (Thyroid Stimulating Hormone): High TSH usually means the thyroid is underactive (hypothyroidism), while low TSH can indicate an overactive thyroid (hyperthyroidism).
2. T4 (Thyroxine): A hormone produced by the thyroid. It helps regulate metabolism. Low levels suggest underactivity, while high levels suggest overactivity.
3. T3 (Triiodothyronine): A more active thyroid hormone, often measured if hyperthyroidism is suspected or being monitored.

Why is it done?

• To diagnose thyroid disorders like hypothyroidism or hyperthyroidism.
• To investigate symptoms such as tiredness, weight changes, mood swings, or irregular periods.
• To monitor treatment in people already diagnosed with thyroid disease.
• To check thyroid health in pregnancy or if there’s a family history of thyroid issues.

5. HbA1c (Glycated Haemoglobin)
Purpose: Measures your average blood sugar over the past 2-3 months.< br>strong>What it measures: HbA1c reflects the percentage of haemoglobin (a protein in red blood cells) that has glucose (sugar) attached to it
The more sugar in your blood over time, the higher your HbA1c level will be.

Why is it done?

• To diagnose type 2 diabetes or prediabetes
• To monitor how well your diabetes is being managed
• To check long-term blood sugar control, rather than just a one-time snapshot like a finger-prick test

What the Results Mean:

• Lower HbA1c = Better blood sugar control
• Higher HbA1c = Poorer control, increasing the risk of complications like nerve damage, heart disease, and kidney problems

6. Lipid Profile (Cholesterol Test)
Purpose: This test checks your risk of heart disease and stroke by measuring the levels of fats (lipids) in your blood. It helps identify whether you’re at risk of developing conditions like atherosclerosis, which can lead to heart attacks or strokes.

What It Measures:

• Total Cholesterol: The overall level of cholesterol in your blood.
• HDL (High-Density Lipoprotein): Known as “good” cholesterol because it helps remove excess cholesterol from your arteries.
• LDL (Low-Density Lipoprotein): Often called “bad” cholesterol; high levels can lead to plaque buildup in blood vessels.
• Triglycerides: A type of fat in the blood. Elevated levels can increase your risk of heart disease, especially when combined with high LDL or low HDL.

Why it’s done:

• To assess your cardiovascular risk, especially if you have other risk factors like high blood pressure, diabetes, or a family history of heart disease.
• To monitor how well lifestyle changes (such as diet, exercise, or quitting smoking) or medications like statins are working to improve your cholesterol levels.
• To help guide treatment decisions and keep your heart health on track.

7. C-Reactive Protein (CRP) / Erythrocyte Sedimentation Rate (ESR)
Purpose: Detects inflammation or infection in the body.
What it measures:

• CRP (C-reactive protein): A blood test that shows a quick rise in response to inflammation in the body, making it useful for detecting infections or monitoring acute inflammatory conditions.
• ESR (Erythrocyte Sedimentation Rate): A slower, non-specific test that measures how quickly red blood cells settle in a test tube, which can suggest the presence of ongoing inflammation or chronic conditions like autoimmune diseases.

Why it's done:

• Diagnose infections, autoimmune conditions, or chronic inflammation.
• Monitor conditions like rheumatoid arthritis.

8. Iron Studies, Ferritin, Vitamin B12 & Folate
Purpose: These tests help identify the underlying causes of tiredness, fatigue, or anaemia by checking key nutrients involved in red blood cell production and energy levels.

What it measures:

• Ferritin: Indicates the amount of stored iron in your body — low levels suggest iron deficiency.
• Serum Iron & Transferrin: Show how much iron is circulating in your blood and how well it’s being transported.
• Vitamin B12 & Folate: These are essential for making healthy red blood cells and for proper nerve function.

Why it’s done:

• To detect iron deficiency anaemia, a common cause of fatigue and weakness.
• To identify vitamin B12 or folate deficiencies, which can lead to tiredness, memory issues, numbness, and other neurological symptoms if left untreated.

9. Vitamin D Test
Purpose: Detects vitamin D deficiency, which is common in the UK due to low sun exposure.

Why it's done:

• Investigate bone pain, muscle weakness, or fatigue.

Monitor: people at risk (e.g. elderly, people with darker skin, or those who cover up and work indoors).

10. Prostate-Specific Antigen (PSA); for Men
Purpose: A screening method to help detect prostate abnormalities, including signs of cancer.

Why it's done:

• Evaluate enlarged prostate or urinary symptoms (such as urinary urgency, urinary frequency, nocturia, post-void dribbling).
• Discussed with men over age 50 or earlier if there's a family history.

How are these tests arranged?

• Your GP will arrange the appropriate tests based on your symptoms or health history; often following NHS blood test guidance.
• Blood may be taken at your GP surgery, or hospital.
• In many cases, GP virtual consultations are used to review your results and discuss next steps.
• Most results are available within a few days. Your GP will contact you if any results need follow-up.

Note: According to NHS England and NICE guidelines, blood tests are done when there’s a clinical reason ; meaning they’re based on your symptoms and medical needs, not just routine requests. This helps avoid unnecessary tests and focuses on what’s truly important for your health.

If you’re ever unsure about your results, don’t hesitate to ask for a blood test interpretation during your GP consultation.

Need help understanding your blood test results? While Ocimum Healthcare does not provide blood testing directly, we offer comprehensive virtual GP consultations to help you interpret your results, explain what they mean for your health, and guide your next steps. If you're feeling tired, dealing with unexplained symptoms, or need support managing a long-term condition; book a consultation today with one of our experienced GPs.