PocDoc vs venous blood draw — why might my results differ?

If your PocDoc results look different from a blood test taken at your GP surgery, you are not alone in noticing this — and there is a clear scientific explanation for why it happens.

Cholesterol levels are not fixed

The most important thing to understand is that cholesterol is not a static number. It changes constantly throughout the day and from day to day, even in the same person.

Research from the National Cholesterol Education Program found that in a healthy individual with no changes to medication or lifestyle:

• Total cholesterol can vary by around 5% day to day
• HDL (good) cholesterol can vary by around 10%
• Triglycerides can vary by around 20%

Our own real-world tracking data from people tested repeatedly over 18 months shows total cholesterol swings of 1.5–1.8 mmol/L in the same person, with no changes to medication or lifestyle.

This means that two tests taken on different days — even by the same method — can legitimately produce different results. This is normal biology, not a sign that either test is wrong.

Different tests can give different readings

There are also differences between the types of test used. A PocDoc test uses a finger-prick capillary blood sample, while a GP blood test typically uses a venous blood sample taken from a vein. These are different sample types, processed by different methods, and it is well established in clinical research that they can produce materially different readings for the same person on the same day.

Neither method is infallible. Published research has shown that between laboratories, platforms, calibrations and sample handling, the same sample can produce clinically different answers. This is why clinicians are trained to treat a single cholesterol result as an estimate with context, not as a definitive label.

One result is a snapshot, not a verdict

This is an important distinction. A single cholesterol measurement is useful — but it is one data point in a biological system that is constantly moving. It tells you something meaningful, but it is not the whole story.

This is also why PocDoc uses the QRISK®3 tool to calculate your cardiovascular risk, rather than relying on a single cholesterol threshold. QRISK®3 uses multiple variables — including your total cholesterol to HDL ratio, age, blood pressure, family history and lifestyle factors — to build a fuller picture of your heart health. This approach is more robust precisely because it does not place the entire weight of a clinical decision on one number.

What should I do if my results look different?

If your PocDoc results look significantly different from a recent GP test, we recommend:

• Not panicking — variation between tests is normal and expected
• Looking at the trend over time rather than a single result
• Sharing both results with your GP — they are best placed to interpret them in the context of your full medical history
• Retesting if you have concerns — repeated testing and trend interpretation is more informative than a single measurement

If you have a technical question about your PocDoc test, please contact us here and we will be happy to help.

If you would like to read the full clinical explanation from our Chief Scientific Officer, Dr Vlad Gubala, you can find his article here: Cholesterol is a measurement, not a verdict — Dr Vlad Gubala

References available on request. Key sources include the National Cholesterol Education Program biological variation data, published lipid analytical variation studies, and PocDoc's own internal tracking data.