Receiving your blood test results can sometimes feel like trying to decipher a foreign language. Whether you have had a test through the NHS or a private service like Medi Test Direct, understanding what those numbers mean is crucial for taking charge of your health. This guide will walk you through how laboratories report results, what reference ranges are, and the various factors that can influence your readings.
How Are Results Reported?
Laboratories typically provide results electronically. A standard report will include the names or codes of the biomarkers tested, the date the measurements were taken, the units used, and any specific notes from the laboratory staff.
Most importantly, the report will show your results alongside a reference range. This scale indicates where your levels fall, whether they are within a normal range (for things like vitamins, minerals, or hormones) or if something specific has been detected (such as a virus).
Your Secure Online Dashboard
At Medi Test Direct, we simplify this process by analysing the data and uploading it to your secure online dashboard, making it easy to see exactly where your results sit within the established normal ranges.
What Are Reference Ranges?
A reference range, often called a "normal range," is the spectrum within which 95% of a healthy population's results fall. This means that 2.5% of healthy individuals will naturally have results above this range, and 2.5% will be below it.
How reference ranges work: 95% of healthy results fall within the normal range
It is important to understand that at the edges of these ranges, there is an area of overlap. A perfectly healthy person might have a result slightly outside the normal range, while someone who is unwell could have a result that falls inside it.
Each laboratory sets its own reference ranges, either independently or based on the manufacturer of the testing equipment. Because different labs use different analysers, a result from one lab might look different from another. Therefore, if you are comparing results from different tests, you should look at where your result lies within that specific laboratory's given reference range, rather than comparing the raw numbers directly.
Should I Worry About an Abnormal Result?
A result that is borderline or slightly outside the normal reference range is not always a cause for immediate concern. Blood test results can be abnormal for many reasons, some of which are entirely benign.
What Can Influence My Blood Test Results?
Many everyday factors can affect your blood test results. Laboratories are aware of these interferences and take them into account, but it is helpful for you to know what they are:
Ten common factors that can influence your blood test readings
🍽️ Fasting and Diet
Tests for diabetes like insulin and glucose are heavily influenced by recent meals. If a test requires fasting, you will usually be asked to abstain from food for eight hours or overnight.
💧 Hydration
Your level of hydration can affect markers for kidney health, red blood cells, and liver function. Keeping well-hydrated gives you the best chance of reliable results.
🏃 Exercise
Strenuous exercise can cause certain liver and muscle enzymes to be released into your bloodstream and can temporarily alter testosterone levels. Wait a few days after intense exercise before testing.
💊 Supplements and Medications
Taking vitamin or mineral supplements will almost always raise your blood levels of those nutrients. Biotin (vitamin B7) is known to interfere with some laboratory tests, including thyroid panels.
📅 Age and Time of Day
Your age influences hormone levels, and laboratories use different reference ranges based on age brackets. Cortisol and testosterone are highest in the morning, which is why these tests are recommended between 8 am and 9 am.
🤒 Illness and Hormone Gels
Taking a blood test while unwell can show temporarily altered white blood cells and elevated inflammatory markers. If you use hormone gels, avoid sampling from the same hand used to apply the gel.