The top reasons for blood sample errors – and how to avoid them
Reviewed by Dr Gigi Taguri
Blood sample errors are common, especially if the blood has been collected via a finger prick test. To get the most out of your home test kit, this article will talk through the top reasons for failed tests and guide you on collecting an error free sample.
1. Your sample is clotted
Clotted blood can’t be tested because the composition of the blood has changed. Any readings collected would be unreliable.
Clotting usually happens when the blood has not been mixed enough. To avoid sending a clotted sample back to the lab, once you’ve collected your blood, seal the vial and gently invert it (tip it upside down) about 8 – 10 times. Do not shake your sample.
2. Your sample is unlabelled, or it has leaked
When doing your home blood test, it’s important to read all instructions carefully. Labels should be filled out and wrapped around the tube, and return forms completed before they are put back into the kit. Make sure your handwriting is clear too.
To avoid leakage, seal the tube securely before posting.
3. The blood is haemolysed
A haemolysed sample means that the red blood cells have broken down or ruptured. To avoid a haemolysed sample:
- Do not squeeze your finger too hard or scrape your finger on the edge of the tube – you’ll get better results if you massage your hand in a downward motion
- Do not shake the tube vigorously
- Do not delay in posting your sample back to the lab – the same day is best
- Do not leave your sample sitting somewhere very cold or hot – package it up and send it back right away
- Do warm up your hands in some warm water before starting. This will get the blood flowing to your fingertips
- Do use the alcohol wipe provided to wipe away the first drop of blood
- Do get your blood flowing by doing some light exercise, such as star jumps
- Do prick another finger if the blood stops flowing from the first after a couple of minutes – you'll have more than one lancet in your kit
- Do start with your ring finger
4. Your sample is insufficient
The vials in your home test kit have lines on them to mark where they should be filled to. If your sample is below this line, it will be difficult to provide accurate results. Sometimes, an insufficient blood test will be because it does not contain enough serum. To avoid this, make sure you are hydrated before doing the test. Read our guide - how to do a blood test at home.
Take control of your health
Learn more about our home blood test kits. Blood tests can provide a picture of your current health. They can also help you to understand your risk of current conditions, such as diabetes and heart disease.
References
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3988264/
https://www.ibms.org/resources/news/clots-in-edta-lavender-top-blood-samples
