Lab Test Reference Ranges – Where Do They Come From?

Reference Ranges and How They Can Help Improve Patient Health Knowledge

Laboratory tests have become so precise and cost-effective that they are one of the major tools that healthcare providers currently are using to help patients identify or rule out health problems.

Doctors, nurses and health technicians are also using e-mail, smart phones and other forms of electronic communication more than ever to share medical information with their clients. Another important tool in understanding how to read and interpret information on a laboratory result is the Reference Range.

But if you are not a skilled medical professional, the language that accompanies the laboratory testing process can be confusing and intimidating.

What Is A Reference Range?

First, let us define exactly what the reference range is. A reference range is a set of estimates that include the upper and lower limits of a lab test based on statistical analytics. If you ever study a laboratory report and come across the section titled “reference range,” you will probably read mysterious words such as “mean,” “value” or “standard deviation.”

But, those terms and some others that are written into the reference range of a laboratory result can be as difficult to understand as a foreign language if you do not have the training needed to understanding medical reports or numbers. To explain it all in a simple way, the reference range is the portion of a laboratory result that gives healthcare providers the best idea for understanding how healthy (or sick) you may be in relation to a host of physical, genetic and population factors.

What Is Information In A Reference Range?

The reference range analyses the following information to help medical professionals understand the health and wellness of their clients:

• Age
• Gender
• Family history
• Your health based on the results of a physical exam or lab test
• The specimen type that is being tested (blood, urine, spinal fluid, etc.)
• Recent changes in your health
• Any medications you are taking
• Other non-laboratory testing information that you may provide

How Are Reference Ranges Determined In Lab Reports?

In general, a reference range is determined by obtaining laboratory reports of medical samples from large populations of people in certain geographic areas. The reporting institution or organization will first define the group of people who will be in the reference range based on the categories mentioned previously (age, gender. race, etc.).

Then a test will be given to a large sample size of people – all with a similar set of biological conditions. The sample group must consist of a minimum of 120 people. Finally, the results of the test are analyzed and the reference range is determined based on the final review of the numbers.

Three general factors can affect the outcome of a reference range:

• Individual variables: These are individuals in each population who are normally healthy, but for some unexplained reason their tests results will always fall outside of the range of the population.

• Statistical variables: Most reference ranges will cover up to 95% of a healthy population, but 5% of the people in the same population will almost always have results that deviate from the range of the overall population.

• Biological variables: Changes in individual hormone rates, age, health, diet and the environment can also impact the numbers of a reference range in a laboratory report.

Reference Ranges And Modern Societies

With so much mass human migration across the world these days, it can be difficult to determine a reference range for a large population in the traditional way. It used to be that differences between reference ranges from diverse populations and distinctive laboratories were easy to categorize. But, some communities that were relatively unchanging 50 years ago – have either become integrated or have completely changed from one ethnic and cultural group to another composition. Individuals and families are using different health care providers and laboratories that they may have traditionally used.

Because modern societies tend to have such diverse populations, medical institutions should probably perform reference ranges in a wide variety of new and innovative ways. Flexibility in methods is likely necessary because the world population is so mobile these days – that a family can start having tests at one laboratory and conclude those same tests at a totally separate test site in a short amount of time.

What Are The Standards?

Medical information and technology are changing at such a rapid pace that consumers need a way to make sure that the laboratory results industry is meeting their needs. All clinical laboratories are subject to federal guidelines, inspection, and extensive review by the Clinical Laboratory Improvement Act of 1988 (CLIA ’88).

Why Reference Ranges Matter

Medical professionals use the information collected and displayed in the reference range to attempt to set an accurate value on the health of their patients. They do this by comparing some health information against that of other people with the same general health characteristics. So, individual health data is matched next to that of people in the same age set, gender category, and ethnic group.

It is one of the many ways that health-care providers can try to determine personal health status – as well as the health standing of a community, region, state or country. The health information that is contained in reference ranges is potentially important because medical professionals may be able to use it to help individuals, families, and communities track health history and improve health outcomes.

Making Informed Decisions for Better Health

For instance, if a group of people in a certain reference range suffers from a high occurrence of a disease like diabetes, a doctor can compare their health information against a group of people who do not suffer as much from the same ailment. Then they can compare the eating habits and lifestyle choices of both groups and make suggestions to modify the behavior of the first group based on what it is that the second group may be doing to eliminate the disease. This is how health and wellness professionals move beyond the simple categories of healthy or unhealthy; young or old; male and female – or the wide number of ethnic or cultural categories that can determine well-being.

Reference ranges have the potential to be a part of the process that helps medical professionals permanently solve a wide assortment of chronic health problems.