Understanding Blood Test Reference Ranges: What's Normal and What's Not

As a professional healthcare practitioner you know that blood tests are essential to good patient healthcare. They can help to diagnose conditions, monitor treatment and assess overall health. But what do all of those numbers on the blood test report mean?

In this blog post, we'll discuss blood test reference ranges and how to interpret them. We'll also cover some common misconceptions about blood tests.

What are blood test reference ranges?

Blood test reference ranges, also known as normal ranges, are the values considered to be within the normal limits of a healthy person. These ranges are based on the results of blood tests performed on a large group of people.

The reference range for a particular test will vary depending on the laboratory that performs the test. Different laboratories use different equipment and methods, which can affect the results.

How to interpret blood test results

If you have requested a blood test for a patient, you will compare the results to the reference range for your patient's age, gender, and other factors. If your patient's results are outside the reference range, it doesn't necessarily mean they have a problem. However, it is essential to determine if further testing or treatment is needed.

For example, a high white blood cell count may be expected in a child fighting an infection, but it may be a sign of leukaemia in an adult.

Common misconceptions about blood tests

Healthcare practitioners need to be aware of some common misconceptions about blood tests.

Myth: An abnormal test result is always a sign of a problem.

Fact: A test result outside the reference range may or may not indicate a problem. It is important to investigate the result further to determine the cause.

Myth: If all the test results are normal, there is nothing to worry about.

Fact: A set of normal blood test results does not guarantee perfect health. There is still a chance that a patient has an undetected problem, especially if they are presenting with symptoms of illness.

Conclusion

Blood tests are a valuable tool for assessing your patient's general health. By understanding normal blood test ranges, you can better understand your patient's results and what they might mean for their health. 

Practitioner Development UK (PDUK) is a leading provider of continuing professional development (CPD) courses for healthcare professionals. We offer a wide range of courses, delivered both virtually and in-house.

We highly recommend the following three courses related to understanding blood test reference ranges:

A92 Blood results: long-term conditions and chronic disease management

A highly experienced trainer delivers this engaging, informative, and interactive course, addressing blood results specific to long-term and chronic diseases.

Aims and objectives:

• To relate common blood tests to long-term conditions
• To connect common blood tests to chronic disease management
• To link common tests together that underpin systems (such as associating Urea & Electrolytes (U&Es) with a Full Blood Count (FBC) for renal anaemia)
• To develop stories to help describe some common tests, like C Reactive Protein (CRP) being a fire alarm

A67 An introduction to basic haematology and biochemistry investigations: Online

This study day provides a firm foundation for understanding essential blood results. It is an ideal first course for clinicians new to blood results interpretation, interested, or wanting a basic review.

Aims and objectives:

• Understand the basic principles of haematology, coagulation, and clinical biochemistry tests.
• Be familiar with appropriate client care relevant to the tests.
• Be aware of what factors can interfere with test results.
• Interpret test results, understanding possible pathological implications of abnormal findings.
• Explore the impact of lifestyle factors such as nutrition and drugs on haematology, biochemistry, and metabolic investigations.
• Apply theory to practice through case study application.

A119 Advanced interpretation of blood results in clinical practice: Online

This programme builds on the fundamentals of interpreting blood tests and provides an advanced understanding of essential blood results. It is an ideal course for delegates who are already comfortable with basic blood tests and want to develop their skills further.

Aims and objectives:

• To outline the ten fundamentals underpinning the advanced interpretation of blood test results.
• To have tested these fundamentals using specialist case studies.
• To be more confident in requesting, interpreting, and applying blood test results, including those out of range.
• Build on your base knowledge of blood tests with more complex second-line blood tests relevant to your area.
• To have an advanced understanding of key blood tests, FBC, LFT, U&E, and how they underpin fundamentals of advanced clinical practice.
• To reflect and apply reviewed principles towards improving practice and patient outcomes.