Blood Test Results Explained
Mar 19, 2026
Blood Test Results Explained
Understanding your blood test results empowers you to take control of your health—this guide explains what common markers mean, what normal ranges are, the difference between "normal" and "optimal," and when you should be concerned. At Blood Test London, a doctor reviews every result, but understanding the basics yourself is valuable.
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How to Read Your Results
The Basic Structure
Element | What It Means |
|---|---|
Test name | What was measured |
Your result | The number |
Unit | How it's measured |
Reference range | "Normal" range |
Flag (H/L) | High or Low if outside range |
Important Principles
"Normal" doesn't always mean "optimal"
Context matters—age, sex, health status
Trends matter—changes over time
Patterns matter—how markers relate
Single abnormals often aren't concerning
Common Markers Explained
Full Blood Count
Marker | What It Shows | Typical Range |
|---|---|---|
Haemoglobin | Oxygen-carrying capacity | 120-170 g/L |
White cells (WBC) | Immune function | 4-11 ×10⁹/L |
Platelets | Clotting ability | 150-400 ×10⁹/L |
MCV | Red cell size | 80-100 fL |
Liver Function
Marker | What It Shows | Typical Range |
|---|---|---|
ALT | Liver cell health | 7-56 U/L |
AST | Liver/muscle | 10-40 U/L |
GGT | Bile ducts, alcohol effect | 9-48 U/L |
Bilirubin | Bile processing | 3-17 μmol/L |
Kidney Function
Marker | What It Shows | Typical Range |
|---|---|---|
Creatinine | Kidney filtration | 60-110 μmol/L |
eGFR | Estimated kidney function | >90 mL/min |
Urea | Protein metabolism | 2.5-7.8 mmol/L |
Thyroid
Marker | What It Shows | Typical Range |
|---|---|---|
TSH | Thyroid stimulation | 0.4-4.0 mIU/L |
Free T4 | Thyroid hormone | 12-22 pmol/L |
Free T3 | Active thyroid hormone | 3.1-6.8 pmol/L |
Lipids (Cholesterol)
Marker | What It Shows | Optimal |
|---|---|---|
Total cholesterol | All cholesterol | <5.0 mmol/L |
LDL | "Bad" cholesterol | <3.0 mmol/L |
HDL | "Good" cholesterol | >1.0 mmol/L |
Triglycerides | Blood fats | <1.7 mmol/L |
When to Be Concerned
Seek Urgent Advice
Very high or very low values (far outside range)
Multiple abnormalities together
Results matching symptoms
Dramatic changes from previous tests
Usually Not Urgent
Slightly out of range values
Single isolated abnormality
Results close to cutoff
Stable over time
Why Doctor Review Matters
Blood tests don't exist in isolation. Proper interpretation requires:
Your medical history
Your symptoms
Your medications
Previous results (trends)
How markers relate to each other
Clinical judgment
At Blood Test London, every result is reviewed by a doctor who considers all these factors.
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Every test includes doctor review—you'll never just get numbers without explanation.
Blood Test London by The Wellness. Blood tests with expert interpretation. A doctor always reviews every result.